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boiler upgrades wildly vary

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b25urgandy
b25urgandy Member Posts: 16
edited February 2022 in Radiant Heating
Location: West Mid Michigan (Grand Rapids area)

Good evening, I've frequented The Wall throughout the years while doing various research tasks when doing upgrades to my prior house. Well as all things in life, we've moved along & into an older, bigger house that has a 67 year old boiler. So now is the right time for me to join officially and to come out of the shadows.

Our house was built in 1966 and has the OG Weil-McLain 225K BTU boiler with 5 honeywell zone values running off of 1'' copper. The house is 2,800 square feet above ground and 1,400 square foot basement. Single pane windows with storm windows, and R11 fiberglass insulation in the walls, with newer blown insulation in attic (I will air seal attic as best I can this spring and add more insulation this fall).

Well as you can imagine, being new to boilers I've called the professionals and have had 10 companies visit my house in the past 14 days to give me their opinion and quotes on new boilers, and with 10 companies you are safe to assume I've gotten just about 10 different boiler size and pump combinations.

I did my own rudimentary manual J as best as I could and I came in around 90K BTU heat loss but take that with a grain of salt. I'm a fairly handy homeowner who is an accountant/auditor by day so it's not perfect and heck, might not be accurate. So numbers are my thing, but I'm not an HVAC Pro by any means.

Here are my house details that matter in addition to the house size/insulation I stated above:
5 Zones totaling 238 feet in total of baseboard radiators: 176 feet of cast iron baseboard radiators (above ground) and just over 62 feet of fin-tube radiators (only in basement):
2 zones on second floor totaling 57 feet of cast iron baseboard radiators averaging 160 degrees.
2 zones on first floor totaling just over 121 feet of cast iron baseboard radiators averaging between 168 - 180 degrees depending on time of day.
1 zone in basement 62 feet fin tube.
Totals will be off based on rounding.

All zones in the basement have 1'' copper piping until they disappear into the floors above. From what's visible in the basement it appears I have a mono-flow plumbing.

My currently weil-mclain 225K BTU boiler is pumped with a Grundfos 15-55 pump. The boiler currently short cycles like crazy and pops and bangs quite extensively, especially at night. I chalk that up to the previous owner not doing any maintenance to it. RIP Weil-McLain.

So onto my concern, no $ numbers involved. My quotes have ranged from 199k BTU vitodens 200, or vitocrossal CU3a. All the way down to 125k BTU vitodens 100, 222 or knight firetube.

The pumps in the quotes are just as wild in variation. From the Taco 007, grundfos Alpha2 26-99, Taco VR3452, and Taco VT2218. (those are the only 4 pumps mixed between the 10 quotes. Most of the installers have commented my house is "underpumped" with the 15-55 on the boiler currently.

One company says the Vitodens 100 is perfect for my house since we have majority cast iron radiators. While another company says since we DO have cast iron radiators, and a lot of them, we're "over-radiated" with and need the Vitocrossal 300 CU3a that's high mass to act as a buffer from further short cycling.

Lastly the companies that agree on the same vitodens or lochinvar knight, don't agree on the size. I have gotten 199k BTU, 125K BTU, 150K BTU. And for the Vitocrossal CU3a I've been given 2 different sizes the 125K BTU and the 160K BTU. As you can imagine I don't know who to think is right as they are all different, from the pumps to the size boilers.

Now back to my unprofessional manual J. If I'm coming up with around 90K BTU, doesn't that put me in the range of the 94K BTU Vitocrossal CU3a, or the 85 or 120K BTU Vitodens 100?

I'm kind of leaning toward the Vitocrossal CU3a 94K BTU boiler to be honest. The reason is 2 companies did a manual J, the other 8 just went to look at it, looked at my radiators by the door and left. The company that did the Manual J went to every room but he didn't quote the vitocrossal, only the vitodens 100. And no, he didn't give me his Manual J numbers because he didn't want his work to be used for another company (and honestly I applaud that because he did the hard work, don't need someone else to take it, but I was just looking to compare to see how close I was).

I know you guys can only discuss based off what you've read because no ones been to my house (no contractor shows up within 100 miles based on the contractor search option on the forum). But based on the info above, what would be your recommended set up? I'm leading 94K BTU CU3a and maybe the Taco VT2218 or the Alpha2 (because the VR3452 is super expensive) being a good fit for my house. But maybe I'm missing something.

Thank you all!

Comments

  • Hot_water_fan
    Hot_water_fan Member Posts: 1,886
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    https://www.greenbuildingadvisor.com/article/out-with-the-old-in-with-the-new

    Use this, it’s based on actual fuel use, not a bunch of estimates. 

    The CU3A doesn’t need an internal circulator correct? That’s a plus as you use lower water temperatures. 
  • b25urgandy
    b25urgandy Member Posts: 16
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    https://www.greenbuildingadvisor.com/article/out-with-the-old-in-with-the-new


    Use this, it’s based on actual fuel use, not a bunch of estimates. 

    The CU3A doesn’t need an internal circulator correct? That’s a plus as you use lower water temperatures. 
    I watched several videos about it, and read extensively about it, and I believe you're correct. No boiler circulator but a system circulator still is used.
  • Jamie Hall
    Jamie Hall Member Posts: 23,446
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    If you used the Slant/Fin Manual J and decent guesses, I doubt that you are far off. I, personally, am wary of estimates based on fuel usage, unless you have a long record (5 years minimum) with consistent maintenance on the boiler and consistent use of the building. Yes, the Slant/Fin calculator takes more time -- and hour or two for a building your size -- but it's quite relaible.

    Having said that either the Vitocrossal or the larger Vitodens (the 120) should be ample; the Vitocrossal is, as you note, a better fit. As you are aware -- as a lurker (welcome aboard!) installation is 90% of the game
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Paul Pollets
  • b25urgandy
    b25urgandy Member Posts: 16
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    If you used the Slant/Fin Manual J and decent guesses, I doubt that you are far off. I, personally, am wary of estimates based on fuel usage, unless you have a long record (5 years minimum) with consistent maintenance on the boiler and consistent use of the building. Yes, the Slant/Fin calculator takes more time -- and hour or two for a building your size -- but it's quite relaible.

    Having said that either the Vitocrossal or the larger Vitodens (the 120) should be ample; the Vitocrossal is, as you note, a better fit. As you are aware -- as a lurker (welcome aboard!) installation is 90% of the game

    Yeah I used the Slant/fin app.

    Do you have any input on type of pump? I like the VT2218. But if its not big enough the VR3452 would be a great option as its variable range on the pump curve looks more broad than the Alpha2 26-99.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,629
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    @b25urgandy

    You don't mention if your old boiler has quit or if this is an emergency install. If not by all means sit on this until spring and continue with your research.

    90K sounds light to me but that is nothing but a guess.

    I would use the Slant Fin app as @Jamie Hall mentioned and you can compare the manual J to that.

    Also @offdutytech does not advertise but does excellent work he is in Michigian don't know if he covers your area. you could pm him

    As far as pumps are concerned that's usually decided by how much heat you have to move and to know that the heat loss comes first, then the boiler then the pumps and piping design.
  • Shahrdad
    Shahrdad Member Posts: 120
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    You must've meant a 57 year old boiler. At first I was wondering why they would put a 1955 model year boiler in a 1966 house. . .
  • b25urgandy
    b25urgandy Member Posts: 16
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    @b25urgandy

    You don't mention if your old boiler has quit or if this is an emergency install. If not by all means sit on this until spring and continue with your research.

    90K sounds light to me but that is nothing but a guess.

    I would use the Slant Fin app as @Jamie Hall mentioned and you can compare the manual J to that.

    Also @offdutytech does not advertise but does excellent work he is in Michigan don't know if he covers your area. you could pm him

    As far as pumps are concerned that's usually decided by how much heat you have to move and to know that the heat loss comes first, then the boiler then the pumps and piping design.

    It's working currently, but it's short cycling and banging really loud while running. During its longer run time (5-10 minutes) it bangs so loud we can hear it upstairs in out bedroom when we're trying to sleep. We were doing the research on prices/sizes. With out old house when we got that furnace replaced the sizes were all the same, which was great. But now they range spectacularly in BTU sizes, which has me worried that we'll have an oversized unit.

    When you say 90K sounds light, but its a guess. Did you mean light as in too small? Sounds like a dumb question but just want to verify.
  • bburd
    bburd Member Posts: 923
    edited February 2022
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    If 90K Btuh is the heating load, you need to select a boiler with a NET OUTPUT (IBR rating) at least that high. This is less than the gross fuel INPUT of the boiler, not all of which is available to heat your house due to losses in the exhaust gases, boiler jacket, piping etc.

    Bburd
  • offdutytech
    offdutytech Member Posts: 133
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    Love the Grand Rapids and West Michigan area, but it's a bit too far for us to do a job. We are located in the Detroit area. 
    Just off the top of my head I would say 90K is too small. I would double check the size using the Slant Fin app. As others said if you can hold off for a few months until the weather is better for a whole new system install. For the time being have you had the system serviced to ensure that you don't have air issues in the system? A possible solution right now would be to maybe have a new pump installed if it's being under pumped.
    You mentioned that it's zoned and a mono flo system? Maybe some pics would be helpful to get the bigger picture of the system. 
    If you are getting quotes on new boilers please consider the following:
    1. How available are parts?
    2. Ease of use to work on.
    3. When changing cast iron to condensing. Make sure you have at least a magnetic separator installed at min or the contractor includes cleaning / flushing the system. 
    4. Are you zoning with pumps or zone valves? If zone valves my go to are the Taco Sentry line with a Taco zone control panel.
    5. Pump away ( see Dans book)
    6. Know that condensing boilers have more moving parts and will require more maintenance.  For our customers we always we explain this and find in the more rural areas people elect cast iron based on the KISS principal. 


  • psb75
    psb75 Member Posts: 845
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    I think its great that the contractors you have had in are promoting Viessmann boilers. Being in Western MI is an advantage because Viessmann has a bigger and better presence on that side of the state. I struggle greatly on the east side of the state north of Detroit finding support for two Viessmann boilers installed several years ago (Vitodens 200 B2HB and 222-F) But I have been happy with the boilers and installs themselves. I found a contractor that was a dedicated "wet-head" but not a Viessmann guy. He is now.
    Be aware that mod/con boilers can operate efficiently in a wide range of output--if installed properly. Note the turndown ratio of a given boiler. Trained installers should be paying CLOSE attention to the type and amount of radiation in your house. Think about changing the type of radiation in the basement--cast iron bb, or panel rads. Air-sealing the house is also very important. More insulation on top also very good.
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,886
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    I, personally, am wary of estimates based on fuel usage, unless you have a long record (5 years minimum) with consistent maintenance on the boiler and consistent use of the building. 
    Depends on the interval you can get, my utility gives us daily gas usage. Which shows that a cold month’s worth of data is as good as several years. If SlantFin or pen and paper comes close to the fuel consumption on the coldest days they’re great! If not, they’re a waste of time. Doing both is a good check. 
  • b25urgandy
    b25urgandy Member Posts: 16
    edited February 2022
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    Love the Grand Rapids and West Michigan area, but it's a bit too far for us to do a job. We are located in the Detroit area. 
    Just off the top of my head I would say 90K is too small. I would double check the size using the Slant Fin app. As others said if you can hold off for a few months until the weather is better for a whole new system install. For the time being have you had the system serviced to ensure that you don't have air issues in the system? A possible solution right now would be to maybe have a new pump installed if it's being under pumped.
    You mentioned that it's zoned and a mono flo system? Maybe some pics would be helpful to get the bigger picture of the system. 
    If you are getting quotes on new boilers please consider the following:
    1. How available are parts?
    2. Ease of use to work on.
    3. When changing cast iron to condensing. Make sure you have at least a magnetic separator installed at min or the contractor includes cleaning / flushing the system. 
    4. Are you zoning with pumps or zone valves? If zone valves my go to are the Taco Sentry line with a Taco zone control panel.
    5. Pump away ( see Dans book)
    6. Know that condensing boilers have more moving parts and will require more maintenance.  For our customers we always we explain this and find in the more rural areas people elect cast iron based on the KISS principal. 


    Ask and you shall receive. Here is a link to an imgur album: https://imgur.com/a/CuZWR4m
    I'll also post pictures in line here too.
    To answer your other questions.
    1.I believe parts are available seeing that 8 out of the 10 contractors quoted a viessmann, the other two quoting exclusively Lochinvar, and most willing to do both brands.
    2.I wanted to keep it easy for HVAC pros to work on so the location it's currently at should be fairly good.
    3.All of the quotes with itemized list of install items do show some type of magnetic filter/air seperator combo. I might also ask for a dedicated magnet/particulate filter à la carte.
    4. We have zone valves and will be keeping zone valves and I did specifically ask for Taco Sentry zone valves funny enough.
    5. just found that post/book on this forum. I will read the post and look for the book too.
    6. That's one reason why I kind of fell for the Vitocrossal. I like the idea of large heat exchanger with larger water channels. should be easier in theory to "self clean" and to be cleaned with less areas for "pinching" of debris and stuff, right? Eh, IDK. But yes, we're usually pretty good about regular maintenance and I've asked several of the installers if they offer a time of purchase maintenance plan at a discount for X-amount of years. Just like my car, I can do basic maintenance but I'm not going to do things I know trained professionals went to school or apprenticed years to get proficient at. I.e. I can change a furnace air filter, blow out the dust with compressed air from the squirrel cage blower. But a boiler?.. It's completely foreign to me and I'll leave that up to the company that installs one when time comes.










  • Jamie Hall
    Jamie Hall Member Posts: 23,446
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    Note that I have no problem with using historical fuel usage -- if it is your own, and you know what, if any, changes have been made to the structure or to the system or the usage pattern. Otherwise, honestly to me anyway, it's a bit like saying to my lead-footed wife "sure! I can get 55 miles per gallon out of this car" and she goes out and gets 25 and gets mad...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Hot_water_fan
  • b25urgandy
    b25urgandy Member Posts: 16
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    psb75 said:

    I think its great that the contractors you have had in are promoting Viessmann boilers. Being in Western MI is an advantage because Viessmann has a bigger and better presence on that side of the state. I struggle greatly on the east side of the state north of Detroit finding support for two Viessmann boilers installed several years ago (Vitodens 200 B2HB and 222-F) But I have been happy with the boilers and installs themselves. I found a contractor that was a dedicated "wet-head" but not a Viessmann guy. He is now.
    Be aware that mod/con boilers can operate efficiently in a wide range of output--if installed properly. Note the turndown ratio of a given boiler. Trained installers should be paying CLOSE attention to the type and amount of radiation in your house. Think about changing the type of radiation in the basement--cast iron bb, or panel rads. Air-sealing the house is also very important. More insulation on top also very good.

    Yeah my last house i learned quick how important insulation was to a house. We had a huge cathedral ceiling in my living room. The bottom of it was a fireplace, but it was in the middle of the house, not an outside wall. House was an early 80's build. On top of the firebreak to the attic they placed no insulation there, i understand clearance to combustibles, but there was nothing above the cavity or the whole wall down to the fireplace. Hot summers and cold winters we couldn't figure out. we air sealed my attic, blew in approximately r60 worth of value up there and still it was uncomfortable. I finally had enough and bought a FLIR for my phone and sure as sin. That whole wall that and cavity that goes through the heart of our house was all blue/purple in the winter, and red/orange during the summer. I finally tore into the wall and found that there wasn't insulation. Well long story short we actually removed the fireplace and turned that alcove into an entertainment center which was nice, i turned the cavity on the second floor into a closet and in the attic i added a lot of insulation. well, that solved our issue as we had no more air infiltration into that area, house was super comfortable after that.

    Changing the basement radiator wasn't something I thought of. I might look into that here when we finish the basement. Why would you recommend that change? Is it not good to have miss-matching radiator styles? I like the idea of radiation panels since it will be a living space and a child play area.
  • mattmia2
    mattmia2 Member Posts: 9,749
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    Are you sure it is monoflow and not just a bunch of series loops? Monoflow needs adequate main flow to generate enough flow at the diverter tees so it would work poorly with inadequate pump sizing.

    With a modcon and that many zones it should be piped primary secondary so you dont have to be very careful about the resistance of all the potential zone call combinations to ensure adequate flow through the boiler.

    It should be set up with outdoor reset to make it run long calls to prevent short cycling. I think if you get this close you won't need a buffer tank especially with the extra mass of the cast iron baseboards. I think the viessman, at least some models, can take the zone calls directly and set a different curve for each zone.

    You could calculate the output of the cast iron baseboard and see what water temp is needed to produce your calculated heat loss. Then you can figure the hest loss on average and mild days and see what water temp is needed there. That will tell you how much of the time the boiler can run in condensing mode at the 90+ efficiency instead of in the 85% range.

    The water temp will fall as it gets further from the boiler and has given off heat to baseboards, especially if your system is a series loop. Better designs use more baseboard as they get further from the boiler to get the needed output with the cooler water. You should approximate this in calculating output, at very least by calculating the output temp of one room and using that as the supply for the next, if it is a series loop rather than monoflow with diverter tees.

    Does this system also make dhw?
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,886
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    Otherwise, honestly to me anyway, it's a bit like saying to my lead-footed wife "sure! I can get 55 miles per gallon out of this car" and she goes out and gets 25 and gets mad...
    I liken it to guessing someone’s height - you could measure their foot, inseam, and arm length or you could just check their chart. 
  • b25urgandy
    b25urgandy Member Posts: 16
    edited February 2022
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    mattmia2 said:

    Are you sure it is monoflow and not just a bunch of series loops? Monoflow needs adequate main flow to generate enough flow at the diverter tees so it would work poorly with inadequate pump sizing.

    With a modcon and that many zones it should be piped primary secondary so you dont have to be very careful about the resistance of all the potential zone call combinations to ensure adequate flow through the boiler.

    It should be set up with outdoor reset to make it run long calls to prevent short cycling. I think if you get this close you won't need a buffer tank especially with the extra mass of the cast iron baseboards. I think the viessman, at least some models, can take the zone calls directly and set a different curve for each zone.

    You could calculate the output of the cast iron baseboard and see what water temp is needed to produce your calculated heat loss. Then you can figure the hest loss on average and mild days and see what water temp is needed there. That will tell you how much of the time the boiler can run in condensing mode at the 90+ efficiency instead of in the 85% range.

    The water temp will fall as it gets further from the boiler and has given off heat to baseboards, especially if your system is a series loop. Better designs use more baseboard as they get further from the boiler to get the needed output with the cooler water. You should approximate this in calculating output, at very least by calculating the output temp of one room and using that as the supply for the next, if it is a series loop rather than monoflow with diverter tees.

    Does this system also make dhw?

    I'm potentially not sure. But one company that came to give a quote said it is a monoflow system. and walked me around to show me the supply and return tee's that were visible in the basement like the two i posted pictures of above. The main supply lines are 1" and the mono flow tees supply the radiators with 3/4" copper.

    Talking about that cast iron basement water temp and calculating the time running in condensing mode at 90+% efficiency makes me realize i need to do some more research in understanding how exactly a condensing boiler works, or "condenses"

    Edit: Also this currently is not set up for an indirect hot water heater. We want the new boiler prepped to have a indirect water heater hooked up when our current tank kicks the bucket.
  • offdutytech
    offdutytech Member Posts: 133
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    Based on some of the pics. I would agree that you would want primary/ secondary piping. With the mono flow tees you might want to do zoning via zone ECM zone pumps. Might drive cost up more, but with your system it might make more sense.  The reason why I like the Taco Sentry zone valves is that you can get them at Menards, allowing customers to replace the tops if needed. 

    @psb75 Viesmann products in SE MI are mainly sold via Johnstone Supply so the tech support is not as good as Lochinvar in this area. I really like Viesmann products, I find that cost wise Lochinvar is priced a bit better is this market because it's sold a several different supply chains. Plus Lochinvar has a distribution center in the area. 
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 9,749
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    The pics weren't there when I started writing. It is indeed monoflow. I too think zoning by pumps might be better with the monoflow. You can make it work with zone valves with a pump with relatively the same flow over widely varying head in its curve.

    I like the zone centry valves because they are very non restrictive, the control head pops off without tools and it uses Phoenix connectors for the connections.

    The monoflow won't be as bad supply end to return end with water temp variation to the emitters but it still isnt constant. Maybe others can comment better on how that works with monoflow.
  • b25urgandy
    b25urgandy Member Posts: 16
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    mattmia2 said:

    The pics weren't there when I started writing. It is indeed monoflow. I too think zoning by pumps might be better with the monoflow. You can make it work with zone valves with a pump with relatively the same flow over widely varying head in its curve.

    I like the zone centry valves because they are very non restrictive, the control head pops off without tools and it uses Phoenix connectors for the connections.

    The monoflow won't be as bad supply end to return end with water temp variation to the emitters but it still isn't constant. Maybe others can comment better on how that works with monoflow.

    I wonder if this is why most of the quotes have big pumps like the alpha2 26-99 or the VR3452.

    I might have to ask the installer I end up going with if they would do zone pumps for monoflow.

    However to further throw a wrench in it. I went down to the basement to investigate and found this information:

    My 2 zones on the first floor are a weird mix.
    Zone 1 (not monoflow) just has 2 radiators and are both in my living room, and they are connected in the corner using a 90 degree connector and return to the boiler.
    Zone 2 (monoflow) has those monoflow tees i posted pictures of above, but 1 of the "banks" of monoflow have 3 small 2-3 foot radiators that are all connected not with monoflow tees. Basically one into the other into the other.
    Zone 3 is my master a second bedroom and there is a non-monoflow tee that splits water to the two rooms and then returns via the zone 2 return pipe? Thats what appears to me, does that sound "fine" to you all? IDK. Both rooms feed by this has 2 radiators connected by a 90 degree fitting.
    Zone 4 on the second floor feeds 1 bedrooms and 1 bathroom. but disappear above and I'm unsure if they are monoflow, but would believe they probably are not, and are like zone 3.
    Zone 5 basement copper fin are monoflow.

    So thats what i have, apparently 2 monoflow and 2 non-monoflow. I wonder if we could split these two up? The monoflow with their own dedicated pump and the non-monoflow with their own pump between the two.

    This just gets deeper and deeper for me the more you guys analyze my system lol.
  • b25urgandy
    b25urgandy Member Posts: 16
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    mattmia2 said:

    The pics weren't there when I started writing. It is indeed monoflow. I too think zoning by pumps might be better with the monoflow. You can make it work with zone valves with a pump with relatively the same flow over widely varying head in its curve.

    I like the zone centry valves because they are very non restrictive, the control head pops off without tools and it uses Phoenix connectors for the connections.

    The monoflow won't be as bad supply end to return end with water temp variation to the emitters but it still isnt constant. Maybe others can comment better on how that works with monoflow.


    See my most recent post, as it appears i have 2 monoflow zones, and 3 non-monoflow zones. maybe I could have them replumbed so those 2 zones have their own dedicated pump, and the 3 non-monoflow would have their own pump between the three?

    Or the whole system might be well suited for a Taco VR3452 as its pump curve is massive for head and GPM variation.

    This makes my head spin lol.
    I can tell you that the guy who pointed out my monoflow system didnt do what i just did to confirm each are monoflow (which they aren't) I might be able to see if my mystery zone up stairs is monoflow i have access to some plumbing but its hard to get at. I'll make sure i check it out today.
  • mattmia2
    mattmia2 Member Posts: 9,749
    edited February 2022
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    Is it balanced now? you're going to need someone that will take a good look at the original design to make the new system work well. The multiple emitters connected together on one set of monoflow tees don't concern me if that was designed right, but of some loops are truly a combination of monoflow and series or separate supply/return then you will have to be careful about the temp and flow through those to keep them balanced.

    EDIT: To make it clear, i don't have an issue with different zones being monoflow and others being series or separate supply and return, the zone valves will balance between those. My concern is if different schemes are combined on the same zone.

    Some of those zones are very small so you need to be careful about either picking a boiler with a turn down ratio that will match that load relatively closely even on mild days or get the reset set up so most of the time multiple zones are calling or a combination of the 2, otherwise you will need a buffer tank if you want to avoid short cycling.
    (that only applies to a modcon, the mass of a cast iron boiler will carry it through that varying load.)
  • b25urgandy
    b25urgandy Member Posts: 16
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    mattmia2 said:

    Is it balanced now? you're going to need someone that will take a good look at the original design to make the new system work well. The multiple emitters connected together on one set of monoflow tees don't concern me if that was designed right, but of some loops are truly a combination of monoflow and series or separate supply/return then you will have to be careful about the temp and flow through those to keep them balanced.

    EDIT: To make it clear, i don't have an issue with different zones being monoflow and others being series or separate supply and return, the zone valves will balance between those. My concern is if different schemes are combined on the same zone.

    Some of those zones are very small so you need to be careful about either picking a boiler with a turn down ratio that will match that load relatively closely even on mild days or get the reset set up so most of the time multiple zones are calling or a combination of the 2, otherwise you will need a buffer tank if you want to avoid short cycling.
    (that only applies to a modcon, the mass of a cast iron boiler will carry it through that varying load.)

    Emitters are the radiators correct? Just want to make sure I'm understanding correctly.

    from above: Zone 2 (monoflow) has those monoflow tees I posted pictures of above, but 1 of the "banks" of monoflow have 3 small 2-3 foot radiators that are all connected not with monoflow tees. Basically one into the other into the other.

    The one bank of 3 small 2-3 foot radiators have the outflow of #1 go to the inflow of #2, #2 outflow goes to #3 inflow. #3 outflow goes back to the boiler. Luckily the copper is in the basement and those 3 could be converted to monoflow because they are easily accessible and I've done some soldering. With that done all of zone 2 would have monoflow radiators. Unless this isn't advisable.

    I think when I choose a company I will ask them to come over to go over the system more in depth so they see it and can understand it better too.
  • b25urgandy
    b25urgandy Member Posts: 16
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    I just looked at it appears my 2 zones on the second flow are not monoflow.

    So only 2 zones out of the 5 are monoflow. The rest appear to be one pipe series loops. but the radiators in those loops tie into each other at corners using 90 degree fittings.
  • mattmia2
    mattmia2 Member Posts: 9,749
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    What you have now was the cadillac of systems at the time and installed by a master.

    You want to make sure whoever replaces it does the math and doesn't just pick things that look good, especially with the monoflow loops and the very small zone. The monoflow loops need a minimum flow in the main loop to induce enough flow through the diverter tees. That small zone will need some care to make sure it doesn't short cycle.

    An emitter is some sort of hydronic heat emitter like a radiator or fin tube baseboard radiator or a convector, in your case CI baseboard radiators. Emitter is the more general term, a radiator is a specific type of emitter.

    Series loops where the emitters are all in the same area make sense and are less expensive, monoflow or separate supply/return schemes keep the output emitters in different areas better balanced so they all heat at the same time.

    The radiators in series on the monoflow act as one radiator, it is a good way to save money if they are all in the same area as long as the resistance of the string is low enough to still get enough flow to deliver the needed heat from the monoflow tees.

    I didn't read your previous post closely enough,it wasn't clear to me if you had some zones that were a combination of piping schemes but now I see that you don't.

    The loop that is in series is probably fine especially if they all heat the same area or it is small, no need to change it to a different piping scheme.

    It is a bit puzzling why some of it is monoflow, with that many zones and pipe that small there was little if any saving in materials or labor over just a direct or reverse return layout.
  • hot_rod
    hot_rod Member Posts: 22,262
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    Count on a 10-15% fudge factor in the heat load programs, I suspect your 90K is accurate. A 120 would be adequate, even with an indirect for DHW. Perhaps the 199 bids were combi boilers?

    A mod con would be a good fit as the modulate and may run low temperature for the milder days, increasing efficiency

    One delta P circ for the zone valve circuits, Grundfos Alpha  or any other brand. Not a fan of delta T pumps with ODR a temperature modulation. A 4 in 1 hydraulic separator is a great way to pipe a system with multiple circulators 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • b25urgandy
    b25urgandy Member Posts: 16
    Options
    mattmia2 said:

    What you have now was the cadillac of systems at the time and installed by a master.

    You want to make sure whoever replaces it does the math and doesn't just pick things that look good, especially with the monoflow loops and the very small zone. The monoflow loops need a minimum flow in the main loop to induce enough flow through the diverter tees. That small zone will need some care to make sure it doesn't short cycle.

    An emitter is some sort of hydronic heat emitter like a radiator or fin tube baseboard radiator or a convector, in your case CI baseboard radiators. Emitter is the more general term, a radiator is a specific type of emitter.

    Series loops where the emitters are all in the same area make sense and are less expensive, monoflow or separate supply/return schemes keep the output emitters in different areas better balanced so they all heat at the same time.

    The radiators in series on the monoflow act as one radiator, it is a good way to save money if they are all in the same area as long as the resistance of the string is low enough to still get enough flow to deliver the needed heat from the monoflow tees.

    I didn't read your previous post closely enough,it wasn't clear to me if you had some zones that were a combination of piping schemes but now I see that you don't.

    The loop that is in series is probably fine especially if they all heat the same area or it is small, no need to change it to a different piping scheme.

    It is a bit puzzling why some of it is monoflow, with that many zones and pipe that small there was little if any saving in materials or labor over just a direct or reverse return layout.

    Yeah I figured with the house being a 1960's build. With the monoflow tees I wonder if it would be beneficial to switch that to a reverse flow system? It's all accessible. not financially advisable I know but I wonder if it would help the pressure differential between the type of flow restrictions in my system.

    I contacted the guys I want to replace it and told them I would like them to come back to explain what I've discovered (as evidence by my posts here) while I've been looking deeper into my layout. So far I've found a mislabeled zone, one zone return pipe connects to another zone return pipe "trunk" for lack of better term. So far they've agreed and I'm going to propose to them if the Taco VR3452 would be a good pump with its wide automodulating variable pumping ability. Although Viessmann says their CU3a doesn't require a high head system pump typically due to their low pressure loss heat exchanger design. regardless I feel that pump is kind of a one size fits all for Delta P vs their Delta T VT2218 pump.
  • b25urgandy
    b25urgandy Member Posts: 16
    edited February 2022
    Options
    hot_rod said:

    Count on a 10-15% fudge factor in the heat load programs, I suspect your 90K is accurate. A 120 would be adequate, even with an indirect for DHW. Perhaps the 199 bids were combi boilers?

    A mod con would be a good fit as the modulate and may run low temperature for the milder days, increasing efficiency

    One delta P circ for the zone valve circuits, Grundfos Alpha  or any other brand. Not a fan of delta T pumps with ODR a temperature modulation. A 4 in 1 hydraulic separator is a great way to pipe a system with multiple circulators 


    I was going to have the company I've decided to replace my system come back and I'll show them the type of zones I have and differences in styles.

    For pumps, Viessmann state their CU3a (the boiler I've decided on) generally don't require a high head pump. But I've looked at the Taco VR3452 as it has a very wide scope of variable pumping head/GPM range. As it's a Delta P pump. But since Viessmann doesn't require a high head pump, generally, I wonder if a cheaper ECM pump might be a better fit. I'll pose the installers that question as well. But I feel in my nieve research that the VR3452 might be a "set and forget" pump even though it costs an arm and a leg.

    My 199K BTU quotes were from those who were trying to pitch me a combi boiler yes (Vitodens 222), but some other companies also wanted a normal 199K BTU since I want an indirect. However I've read on this forum and a Viessmann video that you upsize the indirect don't upside the boiler.

    I've kinda decided on the CU3a as I'm on a well and have old cast iron radiators that I'm sure the old homeowner didn't take the best care of, so I dont really want the smaller channels of the wall hung units to get clogged prematurely due to the crap that might be in my piping. Plus the larger volume of the CU3a might tolerate not only that, but my well water as well, if I cannot get all the sediment out before the boiler intake.
  • mattmia2
    mattmia2 Member Posts: 9,749
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    Listen to @hot_rod, he's forgotten more than I'll ever know.

    So far I've found a mislabeled zone, one zone return pipe connects to another zone return pipe "trunk" for lack of better term.

    I meant to mention this. This is no big deal as long as that combined pipe is big enough to carry the flow from both zones which it probably is because of your large number of relatively small zones.

    You should pipe it primary secondary. The boiler will have its own circulator that will keep enough flow through the boiler. You can either do it with a hydraulic separator as @hot_rod suggests or with closely spaced tees. The hydraulic separator has a few advantages over the closely spaced tees.

    The sizing of the circulators should come from the math that the contractor does, it shouldn't be a look at it and guess situation(although the boiler manual may spec one for the boiler flow when it is primary-secondary).

    The monoflow may have been a spec from an architect or the builder.
  • hot_rod
    hot_rod Member Posts: 22,262
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    If you have crappy well water, above 5 gpm or high TDS bring in good water to final fill. You can make or buy deionized water. The Viessmann manual will give you a water spec.
    Even with good water I like to add a hydronic conditioner.

    With iron in the system I highly recommend a dirt separator with a good magnetic function. Check it weekly when you first start up.

    I agree with @mattmia2 that the installer should size the circ. If the current one is adequate, that is a good starting point

    I don’t have hands on experience with that model V, I’ve heard that they can be direct piped like cast boilers?  A hydraulic Sep assures flow even if only 1 small zone is calling, and you get dirt and mag separation 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • clammy
    clammy Member Posts: 3,113
    Options
    Most wont say but go for the long play and stick w cast iron boiler get your chimney lined . Have a hydro separator installed and have the mono flow loop piped w it’s own circulator w check valves treat it properly w it’s own loop being it’s designed w a pressure drop and will perform much better espically when your standard baseboard loops call . as for your smaller zones use zone valve but have flow setters installed and possibly use a grundfos alpha for that set of zones . Mod cons are great but you have to do some math to ensure that there in there condensing mode up till a little above your outdoor design . May will not mention that most of not all your fuel saving will be eaten by either a service contract and or required year maintenance . All mod con have in my eyes a max of about 12 to 15 years w proper service while a cast iron boiler will w little maintaince last a min of twice as long . In either case install a good magnetic dirt separator (adey) if you plan on using any ecm circ pumps and have your water tds level checked And if high have a demineralizer filter added caleffi makes a nice unit . If sized correctly in a lot of cases your system loop will have a higher flow then what the boiler needs and w long loop lengths I would add a little insurance and add a danfoss thermic valve to keep the return water temps up ona start from cold w a few zones calling cheap insurance from prolonged low temp system return temps which may cause flue gas condensation in your chimney . Just food for thought and remember a standard cast iron boiler is easier to repair and install properly while a mod con reguires a lot of everything like planning set up piping , flushing cleaning of existing piping and zones aside from combustion testing and when there’s a issue a smart service tech who isn’t looking at something for the first time and stocks the necessary parts for whenever there is a issue . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    offdutytech
  • b25urgandy
    b25urgandy Member Posts: 16
    Options
    hot_rod said:

    If you have crappy well water, above 5 gpm or high TDS bring in good water to final fill. You can make or buy deionized water. The Viessmann manual will give you a water spec.
    Even with good water I like to add a hydronic conditioner.

    With iron in the system I highly recommend a dirt separator with a good magnetic function. Check it weekly when you first start up.

    I agree with @mattmia2 that the installer should size the circ. If the current one is adequate, that is a good starting point

    I don’t have hands on experience with that model V, I’ve heard that they can be direct piped like cast boilers?  A hydraulic Sep assures flow even if only 1 small zone is calling, and you get dirt and mag separation 

    Thank you,

    Yeah Viessmann says there is no need for primary/secondary piping and could be as simple as a retrofit/swap if the accessory components are competent (mine aren't as my vales, air skimmer, ect are all in rough shape per my pictures).

    It appears if you want to do primary/secondary that Viessmann wants you to use their hydronic separator because it has a well for a temp. sensor that they want you to plug into one of their ECM ports on the boiler brain.

    The company that will be doing the work is coming on Monday, as they were busy Friday and rescheduled. I'll see what the install manager (who's showing up) will say if they will direct pipe or do a separator. I will request an in-line contaminant filter as well if they decide to direct pipe it.

    The company will also put a cleaner in the system run it for a while (not sure days, weeks, ect.) then come drain it, then fill with water+long term conditioner.
  • b25urgandy
    b25urgandy Member Posts: 16
    Options
    clammy said:

    Most wont say but go for the long play and stick w cast iron boiler get your chimney lined . Have a hydro separator installed and have the mono flow loop piped w it’s own circulator w check valves treat it properly w it’s own loop being it’s designed w a pressure drop and will perform much better espically when your standard baseboard loops call . as for your smaller zones use zone valve but have flow setters installed and possibly use a grundfos alpha for that set of zones . Mod cons are great but you have to do some math to ensure that there in there condensing mode up till a little above your outdoor design . May will not mention that most of not all your fuel saving will be eaten by either a service contract and or required year maintenance . All mod con have in my eyes a max of about 12 to 15 years w proper service while a cast iron boiler will w little maintaince last a min of twice as long . In either case install a good magnetic dirt separator (adey) if you plan on using any ecm circ pumps and have your water tds level checked And if high have a demineralizer filter added caleffi makes a nice unit . If sized correctly in a lot of cases your system loop will have a higher flow then what the boiler needs and w long loop lengths I would add a little insurance and add a danfoss thermic valve to keep the return water temps up ona start from cold w a few zones calling cheap insurance from prolonged low temp system return temps which may cause flue gas condensation in your chimney . Just food for thought and remember a standard cast iron boiler is easier to repair and install properly while a mod con reguires a lot of everything like planning set up piping , flushing cleaning of existing piping and zones aside from combustion testing and when there’s a issue a smart service tech who isn’t looking at something for the first time and stocks the necessary parts for whenever there is a issue . Peace and good luck clammy

    The more I learn/read about efficiency curves, flow rate, ect. The more I think that you're right lol. If the boiler doesn't have return temps to condense you're only like 5-7% higher than a normal 80% cast iron boiler those times. I think we're 99% sure we're gonna get a CU3a but I'm going to request not only a temp on the boiler supply lines, but also a temp gauge on the return line so I can monitor the Delta T myself and potentially contact the company if I see that its not condensing like it should. The CU3a has larger water volume and water passages to hopefully decrease potential for clogs and fouling. I hope this will attribute to longer boiler life greater than 12-15 years. Hopefully 20+. heck our CI boiler is from 1970 at least. IT's a shame the PO didn't keep better care and get it serviced yearly.

    I'm hopefull this company does a at time of purchase service agreement I can buy that will be cheaper than calling once a year. Maybe pre-pay for 10 years or so of service at once? Is that a thing? It would be really nice since I'm doing it anyway if I can get some pre-pay numbers and then run my own Time Value of Money (yay being an accountant) to see if the long term savings is there to pre-pay or to save that money now.

    If we end up taking longer to decide are there many good cast iron boilers in this day and age of Modcons that you recommend to research? I've been told about the brute mini and the newer weil mclain CI boilers by installers. only 2 of them decided to talk CI instead of modcon and those two had 2 different models. one with the brute mini the other with the weil mclain.
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,886
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    A lot of the mod-con efficiency gains come from the modulation not the condensing - yes running at condensing temps saves a little, but running at lower temperatures longer is a huge saver on idle loss. Especially with how oversized the typical cast iron boiler is, getting the rated AFUE involves ODR and thermal purge anyway. 
  • b25urgandy
    b25urgandy Member Posts: 16
    Options

    A lot of the mod-con efficiency gains come from the modulation not the condensing - yes running at condensing temps saves a little, but running at lower temperatures longer is a huge saver on idle loss. Especially with how oversized the typical cast iron boiler is, getting the rated AFUE involves ODR and thermal purge anyway. 

    right, obvious oversight of mine.

    I just discovered the HTP pioneer is similar to the CU3a in that its high mass high efficiency, similar but different I guess. Not a lot of info on that on the internet.
    Hot_water_fan
  • GW
    GW Member Posts: 4,702
    edited February 2022
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    There have been threads on here about clocking your gas meter. You can calculate until the cows come home but the most accurate method is to put a stool in front of your gas meter and just clock it. The colder the day- the better. I had a 0° morning a couple years ago (not unusual) and clocked my gas, I can’t remember the numbers but it was about 40,000 BTUs. My house is about the same size as yours, but modernized. I have a 2012 Viessmann Vitodens 100 (B series second generation). Viessmann is currently on the fourth generation.

    I’m a huge fan of the CU3A, I’ve installed a dozen or so. Larger mass, no boiler pump.

    I honestly think half the guys out there that do heat losses, either don’t know what they’re doing or or just doing it for show (or a combination at the two)

    edit--20 years ago when I was just getting into ac, I was working for a builder, did an addition on a house. Had the local supply house do an ac load calc. 2 1/2 tons. I said 'no way this addition is 2 1/2 tons'. I don't recall the details, but we did a small 1 1/2. Point is- just becasue you have someone saying they did a calc doesn't mean piddly doo. I have since done hundreds of calcs.


    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,886
    edited February 2022
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    There have been threads on here about clocking your gas meter. You can calculate until the cows come home but the most accurate method is to put a stool in front of your gas meter and just clock it.

    :)  this is the fuel usage method. Let the meter do the work :)