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New Gas Boiler recommendations?

RedMonte85RedMonte85 Member Posts: 71
Anyone here have any recommendations for a gas mod con boiler? I have about 2400 sq ft to heat. Climate zone 5, radiant above subfloor in half the house and radiant ceilings in the other. Foamed walls and r60ish in the ceiling. Manual J said 25K BTU's for first floor and my basement is just over half of that so say 60K BTU boiler atleast.

My bosch greenstar is done for. Could replace it with bosch again but I am open to recommendations. I am not sure how I feel about aluminum heat exchangers. Would prefer a wall mounted unit. The previous boiler was 103,000BTU which was probably overkill but I like a bit of overkill.

Thanks
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Comments

  • fenkelfenkel Member Posts: 75
    Is the boiler dead?
    Why not cut the output btus % down, you can go as low as 50%.. so try 55 to 60% and see what happens..
  • RedMonte85RedMonte85 Member Posts: 71
    the boiler is dead
  • fenkelfenkel Member Posts: 75
    What caused its death?
  • pecmsgpecmsg Member Posts: 1,258

    Manual J said 25K BTU's for first floor and my basement is just over half of that so say 60K BTU boiler atleast.



    Thanks

    40K sounds much closer.
    60K you'll only run maybe 30% at best
    Brewbeer
  • HVACNUTHVACNUT Member Posts: 3,094
    Has the Greenstar even been alive long enough to be dead already? Seems like they just came out.
    Spray foam walls but no Hot Roof? Or did you mean roof, not ceiling?
    Was the basement sprayed and air sealed?
    Manual J for the first floor and a guesstimate for the basement?
    From such a low heat loss, you might want to size the boiler for DHW needs and adjust the firing rate and SWT for space heat.
    Mod con and overkill isn't a good thing. Size it correctly.
  • hot_rodhot_rod Member Posts: 12,954
    You should always size to the larger load, in some cases that may be the DHW. IF you do need 60K at design condition, and you trust your numbers, then a 60K boiler is what you need.

    I will say load calc tend to have a 10% or more fudge, so if you wanted to go a bit lower boiler size??

    In either case that 50- 60K boiler would be plenty if you are using and indirect for DHW.

    If you are considering a Combi you may want 120K or more to assure 2.5 gpm DHW.

    Most all combis can be derated on the heating side, crank that output down closer to the expected heat load number, add ramp delay and the boiler should be well matched to both loads.

    You can re-adjust at any time, if the heating load hovers closer to 40K, adjust the max fire rate to that.

    Todays mod cons have a wide range of adjustability, ODR, some with 0-10V outputs, very customizable.

    Search for the brands with the best reputation in your area, should 30 or more brands on the market these days. They all have good and bad days regardless of the brand.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • RedMonte85RedMonte85 Member Posts: 71
    The boiler heat exchanger cracked. The house was not properly winterized and the heat exchanger cracked along with the pump housing by the electronics on the bottom. This happened before I owned the place. I was quoted over 2k for the replacement parts and at that cost I mine as well replace the boiler since there could be other things broke as well. I have an existing hot water heater that runs off electric that I use. I dont plan on using the boiler for my hot water, just the radiant heat.

    No hot roof, too much life left on the shingles to tear them off and I wouldnt hot roof a deck without having some sort of exterior insulation unless you want rotting roof sheathing down the road. House is insulated well, brand new windows, all exterior walls have been foamed, cracks between stud plates caulked. The basement will be remodelled in the near future and the joist bays will be foamed when I get around to that portion of the project.

    I dont mind buying a 100K BTU boiler again, just trying to keep the cost down. Looking for a reliable boiler in the 3-4K range.
  • hot_rodhot_rod Member Posts: 12,954
    just checking online, one of the major brands has a 130K range boiler only in the $1900 range, $2100 range for a combi. For the extra few hundred I'd go with a combi for when that electric tank fails. Depending on your DHW bills with that electric, maybe switch to them combi DHW now also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GroundUpGroundUp Member Posts: 902
    How is it zoned? What's the load on the smallest zone if it were calling alone?
  • RedMonte85RedMonte85 Member Posts: 71
    ~800 sq ft radiant above subfloor heat
    ~700 sq ft of ceiling radiant heat
    ~900 sq ft of basement that is not heated yet but will be in the near future via radiant running up the walls 3 ft like wainscoting.

    I am not sure about loads
  • RedMonte85RedMonte85 Member Posts: 71
    hot rod, any chance you could link me or tell me the model # of the combi?
    Should I be sticking with a modulating condensing boiler?

    On a seperate question, do you think if the heat exchanger and the pump froze enough to break it, what are the chances other parts broke too? Does anything else inside the boiler besides the heat exchanger and that pump even carry water?
    Turns out I can get the replacement parts for about 1700 but if I can get a nice new boiler for less than 3K, please point me in the direction
  • Jamie HallJamie Hall Member Posts: 12,378
    Well, there are few other parts in the boiler to freeze and break -- but if it managed to get that cold where the boiler is, I'd give even or better odds that there are weakened or freeze burst sections of pipe out there in the house, just waiting to get you.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • RedMonte85RedMonte85 Member Posts: 71
    There were a few spots but all of that has been replaced
  • fenkelfenkel Member Posts: 75
    Usually in freeze outs, it will burst in several places..if you have copper pipes inside walls you need to pressurize the system and start listening for hissing... you could use water to check for leaks, but i wouldn't do it..
    Pex is more forgiving but still could have issues at couplers, elbows.
    Some baseboards are very thin tubed and those split easy..

    Like others could say..price is a factor and so is parts availability.
    They're all fairly good if installed correctly..
    Ask yourself this..
    What do you want the boiler to do?
    Just provide heat?
    Provide domestic water heating?
    Do you use alot of hot water at a time?
    Do you take baths?
    How many occupants are there in the house?
    Who will be doing the maintenance ?
    How long are going to stay in home?
    Do you real need a modcon boiler?
    A nice small cast iron power vent boiler may work better considering the size of the btus..
    They're about the same price as a price point mod con but could last alot longer.
    If efficiency is important, youll need to forget about oversizing the boiler..
    In fact a little smaller sized boiler could work even better..
    Whats the design temperature of you system?,
    Before you yank out the bosch, check to see what the service temp was for heating the zones..
    Youll have to turn unit on and go through the programs...
    You could also check to see what the old heating zone temp was set at..might help get an idea of supply setting for heat..
    If you go online and read boiler reviews, take with.a grain of salt...
    Alot of complaints result from incorrectly installs and some suffering from poor maintenance...
    We just had a service call the other day on a new boiler we installed.
    Turned out to be a defective pump...( boiler supplied )
    Moral of story,, they'll all sooner or later have a problem..
  • RedMonte85RedMonte85 Member Posts: 71
    I see popular boilers in the 100-130K BTU range seem to be

    Noritz CB199
    Model: CB199DV-NG

    Noritz NRCB199
    Model: NRCB199DV-NG

    Weil-Mclane Aquabalance
    Model: 383100040

    Triangle Tube
    Model: CC 125H

    Burnham K2
    Model: K2WTC-135B-6T00

    Bosch
    Model: ZWB35-3

    The Bosch ZBR35-3 (current broken boiler) and the ZWB35-3 seem to be nearly identical? Maybe just an updated model? Current boiler is vented with 2 pipes out the side of my basement wall, these pipes converge into one at the top of the boiler.

    Approximately how much more difficult is it to install a different brand boiler vs replacing my current bosch with a similar bosch boiler? Putting new brackets into the cement is no trouble and there are just 3 lines that need to get hooked up (gas, return, supply).
  • RedMonte85RedMonte85 Member Posts: 71
    Fenkel, thanks. Ya, its unfortunate most things arent built to last anymore. Only 2 of us in the house, probably kids in a few years. As far as pipes in the walls, this was a gut remodel. It is pretty much new construction at this point. Not sure if we will ever use it for domestic water, currently have an electric water heater. Might want to keep that option open so maybe going with a 100-130K btu might not be a bad idea.

    I am not sure that the information stored on the boiler would be of much use to me. My system was all baseboard heat when I bought the place and it is now radiant floor and ceiling.
  • hot_rodhot_rod Member Posts: 12,954

    ~800 sq ft radiant above subfloor heat
    ~700 sq ft of ceiling radiant heat
    ~900 sq ft of basement that is not heated yet but will be in the near future via radiant running up the walls 3 ft like wainscoting.

    I am not sure about loads

    So 2400 square feet? Usually basement loads are fairly low, even walkout style. I'd take a WAG and say you have or will have a load under 50,000K.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    rick in Alaska
  • lchmblchmb Member Posts: 2,975
    A: I would recommend new, after all the money to fix the old you still would not have a warranty. Spend the money now and have less worries longer.
    B: size the boiler to the load not "a bit bigger" short cycling will kill a new boiler and waste gas...size it as needed
    C: talk with your service providers in your area. If you cant get it serviced it may be the best boiler in the world but junk when it doesnt run...

    IMHO..
  • hot_rodhot_rod Member Posts: 12,954
    I'd guess that you have all low temperature loads, 120F or less, so a condensing boiler would be a good choice. The smallest you will find is 50K, modulated down to 7,700 or so. A cast boiler would not modulate and would need mixing devices. If you had fin tube, radiators or an air handler a cast boiler might make better sense.

    So next you need to decide on your DHW source. A 50K mod con could handle a 40 or 50 gallon indirect and provide plenty DHW for most any family.

    IF you chose a Combi you need to buy at least a 120K to be able to give you continuous DHW, there is no DHW storage.

    So the combi is a two in one device, good for small footprints, moderate DHW production, able to be derated to the heat load.

    All your eggs are in one basket when it goes down, and ALL!! boiler fail at some point. High efficiency boilers come with higher maintenance and repair cost, really no way around that.

    Personally I like the current combi selections. I've had 3 running at my compound, one for 15 years now. Recently updated to a newer model. They fit my family just fine.

    I have sold and installed 10 or so different brands and models. HTP, Lochinvar, Burnham, Weil, Triangle Tube, Laars, Viessmann, MZ, Polaris. I can't say one brand is head and shoulders above the rest, I have had to repair every brand with the exception of that old Laars which was a Baxi re-label.

    I have the most amount of Lochinvar out in customer homes. I personally like the company, the factory and local rep support. I know many of the people there, dating back 25 years.

    I have also had good interaction with HTP, installed quite a few of the "pioneer" Munchkin, some of them are approaching 20 years of run time.

    Boilers are a lot like trucks, you find a brand, & dealer that works for you and stick with them.

    I would highly recommend factory training on how to properly pipe, start up, adjust, maintain, and certainly how to drive the controls. Unless you are a "digital man", control understanding and settings can drive you crazy.

    Know that combining all the required piping, venting, fuel piping, wiring, etc is not always an easy reach for DIYers. Many of the folks helping here at HH have 30 years or more of experience, sizing and installing it is not a one day learning curve.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • HVACNUTHVACNUT Member Posts: 3,094
    I don't know why you keep mentioning 100K + boilers when your heat loss is probably under 50K BTU.
    SuperTechrick in AlaskaCanucker
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,744
    I would fix the old boiler, it's only a few years old
  • fenkelfenkel Member Posts: 75
    If your a diyer...... id find a contractor,who'll come and inspect your work and set the gas valves.
    I was recently.called to the home of a diyer...the install looked like a plate of spaghetti, pipes going every where..
    Needless to say, im glade they called...
    Cause he probably would have
    torched the place.
    Gas line leaked at the shut off valve,
    The wiring for the boiler came via an extention cord..
    He had too many elbows in the exhaust. It sloped the wrong way.
    He didn't believe in gas adjustments...
    After a long chat, we made up an agreement to work with him to repair it correctly.
    One positive note, he did size the boiler correctly...
    We've been back to check on it several times...just to make sure its okay and the owner hasnt done anything else to it...
  • RedMonte85RedMonte85 Member Posts: 71
    After I install the boiler, I will have an hvac guy come and check the flow and adjust the boiler, get the air all out of the lines.
    DIYer, not so much. The specifics of HVAC just happen to fall outside of my realm. Installing the hardware is doable but dialing it in properly is for someone with experience.

    How important is it to size it closely to the needed BTUs? How much efficiency (even if its dialed back) am I losing by having an "overkill" boiler? I just kind of like having the option of DHW in the future.
  • RedMonte85RedMonte85 Member Posts: 71
    The weil mclain aquabalances are priced pretty attractively.
  • hot_rodhot_rod Member Posts: 12,954

    After I install the boiler, I will have an hvac guy come and check the flow and adjust the boiler, get the air all out of the lines.
    DIYer, not so much. The specifics of HVAC just happen to fall outside of my realm. Installing the hardware is doable but dialing it in properly is for someone with experience.

    How important is it to size it closely to the needed BTUs? How much efficiency (even if its dialed back) am I losing by having an "overkill" boiler? I just kind of like having the option of DHW in the future.


    Really no reason to oversize with so many choices these days. Granted all mod cons modulated so the oversizing is not as critical as a single speed cast boiler for example.

    With an indirect connected to a 60K boiler you have twice the horsepower as a conventional gas fired tank style water heater and higher efficiencies. With the family you describe I would think a 50 gallon indirect would be plenty adequate, especially with a mixing valve added.

    Did you get a price on rebuilding the current boiler? I suspect labor charge alone would make a replacement more cost effective, unless you do the rebuild yourself?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • RedMonte85RedMonte85 Member Posts: 71
    The parts alone are close to 1700, I can buy a new boiler for under 3k, theres no point in fixing the one I have considering the unknowns that still exist with the current boiler. House sat vacant for over a year before I bought it. I'll just tear this one out and part it out.

    Right now I'm just trying to decide on what boiler to buy. My distribution panel, switching relay, thermostats and manifolds are all hooked up and ready to go.
  • hot_rodhot_rod Member Posts: 12,954
    most of the boiler brands now off a couple choices, a stripped down price point model, a bit more $$ give you a more robust control. If you want sensor options, wifi option, ODR, etc I would go with the better model. Under the hood many brands share the same components. I prefer the know boiler brands, some of the tankless water heaters turned boiler don't impress me :)

    I'd look for a brand and model that offer an optional supply sensor, ramp delay, limiting feature.

    The Lochinvar Nobel Combi checks all the boxes but is a bit large for your load and you may not want the combi function. I locked my down to 30% firing for the heating mode.

    Download the I&O manuals, they have better info than the sales slick.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • PerryHolzmanPerryHolzman Member Posts: 65
    I understand your logic for replacing a boiler that sat for a year and froze. Given the information you provided above (103,000 Btu) matches the ZBR-35-3 Greenstar 131.

    That has a 3.66 turndown ration (max to min firing rate), and is likely oversized even at minimum firing for a good portion of your heating system.

    There are significant galvanic corrosion concerns with Al based boilers as well - IF they are connected to copper or iron piping and components. That can be overcome with treatment systems; but, you may have to test and adjust the water loop chemistry every year or so.

    Personally, I would avoid that and move to one of the SS for a mod-con or a heavy (thicker wall) Cast Iron heat ex-changers.

    However, if you are deadset on buying a boiler that is significantly oversized... Buying the exact same boiler as you have would provide you with a stash of spare parts down the road... Something to consider. Clean it up nicely and store it properly. Also gives you a place to learn how to take something apart and put it back together (even a service tech might want that).

    I wish you the best,

    Perry
  • RedMonte85RedMonte85 Member Posts: 71
    That lochinvar looks nice and its under 3K. Is that superior to the weil-mclain aquabalance? What are the heat exchangers on these made of? I would prefer stainless over aluminum.

    All being near the same BTUs

    Aquabalance is 800 cheaper than the lochinvar.

    Lochinvar is 600 cheaper than the bosch replacement.
  • PerryHolzmanPerryHolzman Member Posts: 65
    Look at the data sheets and manuals that you can download on the internet to determine HX materials and turndown ratios. You can do your own homework on that.

    More important, talk to several local heating contractors on what boilers they use and why. I had I think 4 companies come in and give me quotes and options. Not that I went with any of those as I wanted the latest and greatest Viessmann Vitodens 200 (not necessarily the best general choice). It did allow me to see and get a lot of information; and allowed me to chose a vendor to install my personal choice.

    I'd advise choosing a boiler that some local heating contractor is installing and servicing... Then you have something that someone can come in and help you later as needed.

    In my opinion, A good heating contractor who knows a specific boiler is of more value than any of the differences on the lower cost boilers out there.

    I wish you the best,

    Perry
  • HVACNUTHVACNUT Member Posts: 3,094
    > @PerryHolzman said:
    > I had I think 4 companies come in and give me quotes and options. Not that I went with any of those as I wanted the latest and greatest Viessmann Vitodens 200 (not necessarily the best general choice). It did allow me to see and get a lot of information; and allowed me to chose a vendor to install my personal choice.
    >
    > Perry

    You wanted Viessmann and knew those companies didn't offer Viessmann, but used their valuable time for your personal benefit anyway?
    I misunderstood, right? Please.
    GroundUp
  • PerryHolzmanPerryHolzman Member Posts: 65
    HVACNUT said:

    > @PerryHolzman said:

    > I had I think 4 companies come in and give me quotes and options. Not that I went with any of those as I wanted the latest and greatest Viessmann Vitodens 200 (not necessarily the best general choice). It did allow me to see and get a lot of information; and allowed me to chose a vendor to install my personal choice.

    >

    > Perry



    You wanted Viessmann and knew those companies didn't offer Viessmann, but used their valuable time for your personal benefit anyway?

    I misunderstood, right? Please.

    That's not how it started. I didn't know what I wanted. I had no idea Viessmann or modcon boilers even existed when I discovered I needed a new boiler asked for the 1st round of quotes.

    But I also got on the internet and Heating Help at the same time and learned about Modcons - and Viessmann was talked about a lot on Heating Help back then. Only 1 contractor of the 4 that I contacted had ever installed a modcon.

    So starting from scratch I let each of the 4 contractors educate me on what they thought was a good boiler and why, and why I should hire them. Several of them pitched aluminum block heat exchanges as the latest thing - and I knew that was a galvanic nightmare based on my engineering work (a lot of galvanic failures in power plants).

    After I learned about the Vitodens and figured that was the best boiler for me I asked who I thought was the best 2 contractors about installing one, and then chose the contractor I was most comfortable with (and they were not the cheapest - and did great work; but, they have never been that interested in servicing it or learning about it and today will not install a modcon for anyone as they had a bunch of Triangle Tube modcons fail after I introduced them to the concept).

    My memory is that all of this occurred in about 1.5 weeks at the start of heating season in 2007 when I discovered that my old boiler (53 years old) was leaking exhaust gases into my basement. My new boiler was installed 3-4 days later after I had the final 2 quotes for the Vitodens (a 2 day job including tearout of the old one and relocating things to the side of the house).

    I recently did a similar thing for a roof on my house. I ended up putting on a all aluminum metal roof on the house.

    I hope that clarifies things,

    Perry
    HVACNUT
  • hot_rodhot_rod Member Posts: 12,954

    That lochinvar looks nice and its under 3K. Is that superior to the weil-mclain aquabalance? What are the heat exchangers on these made of? I would prefer stainless over aluminum.

    All being near the same BTUs

    Aquabalance is 800 cheaper than the lochinvar.

    Lochinvar is 600 cheaper than the bosch replacement.

    I have not installed an aluminum boiler in years, the early ones, 12- 15 years ago were very problematic, hopefully that has changed.

    I know the most about Lochinvar, they provide the best info in their manuals and have always been helpful.

    Some examples of what all mod con manufacturers should offer for design and installation info.



    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • RedMonte85RedMonte85 Member Posts: 71
    I think that I have decided on the HTP UFT 80K btu boiler. It can be turned down to 8k, is a firetube and has a stainless heat exchanger. The price is right and it seems to get favorable reviews.
  • fenkelfenkel Member Posts: 75
    Its a good boiler... follow the install manual....use p/s piping, make sure you use 6 inch cpvc exhaust pipe that came with boiler.itdoes get kinda warm/hot on top of boiler..
    The last one we put in fired right up..
    You hear a lot of noise from hx, but thats air in system, just run it hot for a few days and it will quite down.
    Make sure you use correctly sized pumps to move the water around..
    Cause this Boiler has approx 3 gallons of water in it..
    You might have to do a few adjustment to the operating system..
    One that i had to make was the degrees to turn boiler on was set a little to high..factory setting is 30, worked better at 20 degrees
    Function 17:bo
    Also dont use too many elbows in intake and exhaust lines...
  • RedMonte85RedMonte85 Member Posts: 71
    My pumps should be fine, all new grundfos 15-55f. The exhaust/intake will only have one bend in them.

    Ended up getting an HTP ELU-85WBN
  • fenkelfenkel Member Posts: 75
    Elite ultra?
    Let us know how it works... been interested in it, but its a new model.
  • RedMonte85RedMonte85 Member Posts: 71
    Can corrugated flex pipe like falcon stainless be used to connect the supply and return lines out of the bottom of the boiler?

    HTP gave me some S shaped copper lines that have a collar nut on them but the flex lines would be much faster and easier for my setup
  • hot_rodhot_rod Member Posts: 12,954

    Can corrugated flex pipe like falcon stainless be used to connect the supply and return lines out of the bottom of the boiler?



    HTP gave me some S shaped copper lines that have a collar nut on them but the flex lines would be much faster and easier for my setup

    If the flex is rated for the pressure and temperature you can use them. Be sure they are sized large enough there is a bit of pressure drop in corrugated connectors.

    We sold a corrugated tubing for retrofitting rooftop solar in 1/2 3/4 and 1" size. It's really not much different than CSST tube :)

    Falcon and MetraFlex are a couple brands available.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GestatorialGestatorial Member Posts: 1
    I use the Bosch ZWB35-3 boiler, you should check them out.
    ..
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