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Cast Iron boiler/Monoflo setup changing to ECM and Zone Valves/Manifolds - Done!

Formerly
Formerly Member Posts: 78
edited January 2017 in Gas Heating
Hello, I've been ready A LOT of threads that touch many of these topics and I must say this is a wealth of knowledge - THANKS! However, I am still left thinking - am I doing the right thing? So hopefully my explanation and your (collective) expertise will assuage my fears! OK - on with it!

My current setup -

Colonial house, built 1994, Long Island NY
Gas fired Weil McLain cast iron boiler CGM-5-PI Series 10, circa 1995 (atmospheric vent up chimney flu)
Input, Btu/hr - 140000
DOE Heating Capacity, Btu/hr 115000

1-1/4" Cast Iron supply (about 6' worth) heading to 2 zones (upper and main floor), flow-checked and 1" each

The 2 zones are both monoflo loops spanning the whole basement with 1/2 taps going off to the rads
Radiators are all Burnham "Baseray" cast iron baseboard or Burnham "Radiant" cast iron uprights.
Each zone gets a circulator on the return side, just before the boiler. B&G series 100's for both.

The house gets warm, no problem. So why mess with a good thing?

A basement renovation.

Flushing up the current situation in my joists would be crazy work - so I may as well be crazy and remove the monoflo loops and home run each rad back to 3 manifolds (upper floor, main floor, new basement reno.) So, each manifold is for each floor. I will be doing the home runs in 5/8 pex-al-pex (to match the 1/2 copper legs for the rads). My original idea was to simply use some grundfos alphas in front of each manifold and tie them each to a thermostat, but then I got worried about the returning water temperature being too low. Currently, with all the water sitting in a cold basement in the monoflo loops, the water coming back is cold to begin with - this isn't good for my boiler, right?

So my next idea was a bit more future focused. One day, this boiler is going to crap out, and perhaps I would change it to a modcon, or not (maybe just another cast iron.) Since I do not know yet, why not install the prerequisite Primary/Secondary loop layout and give myself some options down the road? Wouldn't this benefit my current boiler anyway? The return temps would be stabilized more and I could possibly add a DHW down the road as well.

So, I thought out a new layout -

Current boiler (primary) supply and return repiped in copper 1-1/4" with a taco 00e VT2218-HY1-FC1A01 primary circulator heading to a hydrolink.

OK - the logic here is that this taco circulator pays attention to deltaT and can be set in such a way that it will know whether or not it needs to move the primary loop water through the boiler to maintain a nice deltaT, while not going crazy. Is this a good idea?

Heading back to the hydrolink, that is where my zones will be piped from - 3 zones, one for each floor using caleffi 1" manifolds. My top floor will use a 6 loop manifold, my main floor will have a 10 loop manifold, and the new basement will have a 6 loop manifold.

each zone with be circulated on the supply (hot) side by a grundfos alpha (3 of em)

The logic of using the alphas is to achieve the proper head flow for these manifolds. I am not about to try to math out all this pipe for all these rads!! Head hurts too much!

As far as a switch relay, I need the most help here - I was thinking a taco SR506-EXP

This would work with my current boiler, with what I am trying to do right? Also, it would allow me to grow into a modcon if I went that route down the road as well I think.

Main contentions of going this way (overkill) was to accommodate an outdoor temp sensor, a future DHW (with priority) and perhaps one more zone, if needed.

I am hazy on how the boiler will behave in this new ECM world, where to me it seems I can let the primary circulator turn on and off based off of its own intelligence and modulate the boiler firing on its own as well....? Is this crazy talk? This is the one part I have yet to sink time in to.

I think this about sums it up, AM I CRAZY?
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Comments

  • Steve Minnich
    Steve Minnich Member Posts: 2,674
    To me, it sounds like a fun project. If you have to re-pipe everything to gain ceiling height and you have the ways and means to do it right, why not?
    I'm a big fan of the manifold home run distribution system. I think you'd probably be able to use 1/2" PAP instead of 5/8" in most cases. Use manifolds with flow meters and balancing valves and you'll be able to dial it in pretty tight.
    Since you're using the Taco EXP relay, just add the Taco PC-700 reset control. Plug and play.
    Another thing I'd consider is the Taco VR1816 circs.
    Enjoy.
    Steve Minnich
    Minnich Hydronic Consulting & Design, LLC
    [email protected]
  • Brewbeer
    Brewbeer Member Posts: 616
    edited April 2016
    My last house was a mono flow system feeding cast iron baseboard, 1 inch main loop and 1/2 inch feeds/returns for the radiators, all piped in copper. I also finished the basement and had to deal with the piping hanging down from the joists. I moved the main loop up into the joist space. Where the main loop ran perpendicular to the joists, I snapped a chalk line down the joists in the location of the main line, measured up the same distance on each joist using a framing square, and drilled a row of holes all perfectly lined up. I then put a hole through the rim joist and wood siding from the outside that lined up with row of the holes through the joists, and fed lengths of 1 inch copper through the joists from outside, and cut them to the needed length from inside the basement. That made the re-piping of each radiator supply and return pretty pretty easy.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
    Formerly
  • SWEI
    SWEI Member Posts: 7,356
    Also, no need for primary/secondary piping with many of the new mod/con boilers. One pump, one boiler, whole house.

    OTOH if you want to replace with a CI boiler or keep the existing one, a Taco iSeries-R 4-way valve can handle the ODR and also boiler return water protections.
    HatterasguyRich_49SuperTech
  • Formerly
    Formerly Member Posts: 78
    edited April 2016
    Brewbeer said:

    My last house was a mono flow system feeding cast iron baseboard, 1 inch main loop and 1/2 inch feeds/returns for the radiators, all piped in copper. I also finished the basement and had to deal with the piping hanging down from the joists. I moved the main loop up into the joist space. Where the main loop ran perpendicular to the joists, I snapped a chalk line down the joists in the location of the main line, measured up the same distance on each joist using a framing square, and drilled a row of holes all perfectly lined up. I then put a hole through the rim joist and wood siding from the outside that lined up with row of the holes through the joists, and fed lengths of 1 inch copper through the joists from outside, and cut them to the needed length from inside the basement. That made the re-piping of each radiator supply and return pretty pretty easy.

    I did almost exactly this for my in-laws. I kept the pitched legs from each rad in tact including the monoflo tees and simply replaced the copper with pex pulled through holes like you said ( I wasn't willing to drill a hole on the exterior to push copper through, pex was fine in this application. Any air that may have gotten in the main loop would go up to each rad eventually to be bled off. I had it running for a month before closing it in using clear pex (with O2 barrier) and there was no air to be seen, worked great.

    I decided against this here, because I have an enormous steel beam cutting across my basement ceiling and its a perfect channel to run all my home runs back to a manifold, no drilling required!
  • Formerly
    Formerly Member Posts: 78
    edited April 2016

    I would not utilize the VT2218 in a P/S configuration as you have described.

    Yes, it can perform the boiler protection function and slow down if the SWT gets below the setpoint. But, the problem comes in when the pump does its job and the boiler climbs in temperature to setpoint. Now, the VT is going ramp up to speed four and shove way too much water back to the boiler. The ΔT is going to be down in the weeds and the CI boiler controls won't take kindly to that.

    Personally, I'd try to get away from P/S piping if at all possible, and with the CI boiler it certainly is possible. In fact, it is also possible on many of the well designed mod-cons that can accept a low flow rate.

    Use the VT2218 to maintain a reasonable ΔT for the system and incorporate a boiler protection valve to prevent low temps to the CI boiler:


    http://products.danfoss.us/productrange/heatingsolutions/hydronic-comfort-controls/esbe-valves-actuators-controls/thermostatic-boiler-protection-valve/

    No, you most certainly do not need three Grundfos Alphas for the three manifolds. That's massive overkill. The single VT2218 can do the entire job if you keep a low resistance (1" piping) between the boiler and the three manifolds.

    I get what you are saying here - this is actually not too far from my current system theoretically speaking. With this type of layout (with the single circ and 3 zone valves) makes me worry about throttling. So when the cast iron rads around the house get cool, it takes a fair bit of effort to get em warm again, and I am worried that if multiple zones call simultaneously, the deltaT circ will slow to a crawl to protect the boiler (because the return temp is so cold.) Is this a legitimate concern I am having?


    As @Stephen Minnich mentioned, use manifolds with flow meters and balancing valves as these will become more important with the single pump.

    The manifolds specified have built in flow meters, so thats taken care of. I would have to add the balancing valves to the manifolds which is easy, but I have a question - if 2 (or more) zone valves opened at the same time, would I have to then balance those 2 manifolds against each other in this case since I am using a single circulator?


    Depending on the arrangement and location of the manifolds, consider doing reverse return piping back to the boiler.

    Completely possible, all manifolds will be inches apart.
  • Formerly
    Formerly Member Posts: 78
    edited April 2016
    After thinking about what Hatterasguy mentioned, I thought up a different design, that might be less...involved. It is still a primary/secondary, but uses a hydrolic separator.

    This allows me to create a large leg to hold one circulator and branch off to 3 zones containing the manifolds.

    So it would look like this -

    Boiler supply 1-1/4" copper to taco VT2218 deltaT circ.

    freshwater supply/pressure tank next, then

    to a hydraulic separator (also 1-1/4".) This takes care of a bunch of stuff - air sep, particle sep, magnetic sep (to protect ECM's)

    The other side of the hydraulic separator on supply side is 1-1/4" copper with a grundfos alpha leading to 3 legs (all 1-1/4" copper) heading to the 3 manifolds behind the 3 zone valves.

    The returns from these 3 zones will be reverse return plumbed back to the hydro-separator at 1-1/4" copper, and continuing to the boiler return side.

    better than the first design?
  • Formerly
    Formerly Member Posts: 78
    edited April 2016

    However, if you ever will consider a mod-con, the VT will insure that you maintain the desired DT and get the return water temperatures that you need for the efficiency of the mod-con. The Alpha will not.

    I'm pretty sure I would stick with cast iron - the cost and ROI doesn't add up with mod-cons, at least for me right now. I did some reading and can't see any benefit to it, so once my current one kicks the bucket, I would need to replace it with a new cast iron. Any suggestions?


    You haven't confirmed the heatloss or the size of this house but 1" piping from the boiler to the manifold and back is probably more than sufficient. It will easily handle 8 GPM and deliver 80K to the building.

    I will find time to do this the right way and report back - kids and weekends don't permit these things!
  • SWEI
    SWEI Member Posts: 7,356
    Formerly said:

    I'm pretty sure I would stick with cast iron - the cost and ROI doesn't add up with mod-cons, at least for me right now. I did some reading and can't see any benefit to it

    What efficiency numbers are you using to compare the two? Please tell me it isn't AFUE.

    In my experience, a properly sized mod/con replacement will net 30% fuel savings minimum over an existing CI boiler -- more typically 40-55%. If I had to guess, I'd put the savings over a properly sized and controlled modern CI boiler at somewhere around 20-25%.
    Steve Minnich
  • Steve Minnich
    Steve Minnich Member Posts: 2,674
    edited April 2016
    I think Buderus cast iron boilers lead the pack in the CI category.

    GL-180M Gray Cast Iron

    Buderus GL-180M silicone injected, gray cast iron has excellent corrosion resistance, exceptional casting characteristics, 40% greater flexibility and elasticity as well as high thermal conductivity. Buderus developed the special substances that are impregnated
    during the casting process to improve the mechanical properties of cast iron. The graphite precipitates into smaller, modified flakes which produce GL-180M cast iron with 40% greater elasticity and a high silicone barrier for corrosion protection. Gray cast iron obtains its superior material characteristics primarily from a high carbon (graphite) and silicone content. Additional elements further enhance the properties of the GL-180M. The graphite appears in two different forms in the microstructure: nodular form producing excellent tensile strength and great elasticity and graphite flakes producing excellent corrosion resistance against acidic combustion products.
    Steve Minnich
    Minnich Hydronic Consulting & Design, LLC
    [email protected]
    4Johnpipe
  • SWEI
    SWEI Member Posts: 7,356
    That's the same iron that Viessmann used in the Vitogas. It's currently used by Burnham in their Series 3 and also the ES family.
  • Steve Minnich
    Steve Minnich Member Posts: 2,674
    Thanks Kurt. I didn't know that. The last Burnham I installed was a Series 2 a long time ago.
    Steve Minnich
    Minnich Hydronic Consulting & Design, LLC
    [email protected]
  • Formerly
    Formerly Member Posts: 78
    Thank you all for your input!! I am still working out which design would be the most cost effective for my situation. You have certainly helped me work out some kinks in my original idea! Once I settle on a plan, I will surely take pictures and post my progress!


    To get back to Hatterasguy, I completed my Heat/Loss analysis and my current house layout (2 floors, 2 zones) is about 55,000.
    Adding a third zone for the basement remodel would add another 20,000 for 75,000 grand total (not including mechanical room)

    I laughed out loud considering this number and the unit I currently have. I won't be having a problem adding this to this current unit I'm assuming.

    Also, I want to apologize to Hatterasguy - as I was reading back, I didn't mean to outright dismiss his suggestion to stay away from a P/S system - may I ask what benefits there would be (aside from cost) to avoid the P/S system? Is it overkill?

    Also, as I was paying more attention to my current system, I realized that my boiler seems to be well below the 180 degrees it should be resting at (the internal thermostat is correctly set to 180, however it doesn't seem to fire up to bring the temperature back up, it only fires up when a zone calls. Is this correct behavior? Thanks again for all of your help!
  • Formerly
    Formerly Member Posts: 78
    SWEI said:

    Formerly said:

    I'm pretty sure I would stick with cast iron - the cost and ROI doesn't add up with mod-cons, at least for me right now. I did some reading and can't see any benefit to it

    What efficiency numbers are you using to compare the two? Please tell me it isn't AFUE.

    In my experience, a properly sized mod/con replacement will net 30% fuel savings minimum over an existing CI boiler -- more typically 40-55%. If I had to guess, I'd put the savings over a properly sized and controlled modern CI boiler at somewhere around 20-25%.
    I was comparing purchasing a CI with 80%+ to the general 90%+ of modcons, but have no actual numbers to back up my blathering regarding this - I was reading stuff all over the place and just got a "gist" that it would be cost prohibitive in the end. I obviously could be (and probably am) completely wrong. Now that I have done a heat loss, I could probably more accurately settle this right?
  • Formerly
    Formerly Member Posts: 78
    edited April 2016
    I've also calculated the radiator btu's as well.

    First Floor - 70,008 BTU Creation (Calculated Loss was 35,000)
    Second Floor - 27,924 BTU Creation (Calculated Loss was 17,555)

    These numbers were for 180deg water at 1gpm.

    Does this look normal?






    Other stats (and how I calculated):
    Burnham Radiator Calculation Sheet

    First floor -
    Burnham Baseray -
    59LF * 480BTU/HR per foot @ 1GPM & 180deg water
    = 28,320 BTU/HR

    Burnham "Radiant" radiators -
    85.5 Linear Inches of radiator
    (38 Sections = 85.5 Sq Ft * 240BTU/HR Less 10% for being recessed in wall = 41,688 BTU/HR)



    Second Floor -
    Burnham Baseray -
    44LF * 480BTU/HR per foot @ 1GPM & 180deg water
    = 21,120 BTU/HR

    Burnham "Radiant" radiators -
    31.5 Linear Inches of radiator
    (14 Sections = 31.5 Sq Ft * 240BTU/HR Less 10% for being recessed in wall = 6804 BTU/HR)


    Is it normal to have such an over calculation in heat potential?
  • Formerly
    Formerly Member Posts: 78
    edited April 2016


    A mod-con is in your future, if you understand the potential of what you have there.

    This is the contingency of why I wanted to pipe a P/S system now and get it over with - just in case. The man who built & lived in this house was a builder - there are many little "upgrades" all over the place that most houses don't have. For that, I am fortunate.
  • Formerly
    Formerly Member Posts: 78
    Sorry to be a pain Hatterasguy, but can you help me understand with a bit of technical detail how the single loop with multiple zones using one circ and zone valves would maintain proper deltaT for a CI boiler such as mine, and eventually a ModCon? I've been spending so much time with the P/S concept, I feel I am overlooking the simplicity of your suggestion.
  • Formerly
    Formerly Member Posts: 78
    <--- Idiot alert - what is this SWT you speak of?
  • Formerly
    Formerly Member Posts: 78
    OK, interesting. I think I am grasping what you are saying and it leaves me to think of this scenario:

    Current CI boiler with one grundfos alpha doing its autoadapt spiel. It leads to 3 zones consisting of balanced manifolds. A simple reverse return heading back to the CI.

    When the day comes to change to a ModCon, change the pump to a pump able to handle the 0-10V output you describe from the ModCon. This will allow the pump to do the ModCon's bidding, removing the issues and allowing it to do it's outdoor reset thing. Considering the thermal mass of the system, this piping will be optimal?

    Also, will this still be ok if I ever add a DHW loop? Would I have to just zone it as if it were a zone like the rest, and give it priority?




  • Formerly
    Formerly Member Posts: 78
    Hatterasguy - would you say this .pdf sums up your design suggestion?

  • Formerly
    Formerly Member Posts: 78
    another general question - would I be sacrificing too much by moving down from 5/8" pex-al-pex home runs to 1/2" pex-al-pex home runs? again, these are going to 1/2" copper

    GPM CHART
  • Formerly
    Formerly Member Posts: 78



    I fundamentally disagree with the high flow requirement provided one procures one of the latest generation of mod-cons that can accept flows down to 1 GPM.

    Due to my current battle with a low mass and low flow mod-con, I would agree that higher mass would be your best friend in getting a primary only system to function properly with the desired DT.

    Can you point me to that particular brand/model so I can continue to educate myself? I have been looking rather unsuccessfully based off of these specifications and find myself sifting through too many .pdfs!


    A bit confused here.

    A "home run" is the line from the boiler to the manifold(s). No, you don't want 1/2" or 5/8" for that (those) line(s).

    For the lines to the individual rads, I believe we concluded that 1/2" would be fine considering the distance isn't that great.

    The head on the longest loop determines flow rate with a specific pump.

    Sorry - I was referring to the stretch of Pex-al-Pex between the rads and the manifolds. Basically, there are more fittings in stock for the 1/2" PAP (FostaPex) than there are for the 5/8" and considering I have a propress, I'd like to stay in that realm for the simplicity of it. I can only think of one radiator that would need more flow (2nd floor, long length and piped with 3/4 copper) but thought that a balanced manifold would allow it to sufficiently receive heat.

    As an aside, anyone have thoughts on Viega FostaPex?
  • Steve Minnich
    Steve Minnich Member Posts: 2,674
    A home run is the line from the manifold ports to the individual radiators. Typically, 1/2" is sufficient if you're using a 20 Delta T and the radiator's EDR doesn't exceed 15K.
    Steve Minnich
    Minnich Hydronic Consulting & Design, LLC
    [email protected]
  • Formerly
    Formerly Member Posts: 78
    Using the Burnham chart, I calculated the length of the rad (18ft total) and used a SWT of 160 at 1gpm to arrive at 6660.

    If I bump it to SWT 170 at 1gpm, its 7740.
  • Formerly
    Formerly Member Posts: 78
    edited April 2016
    I calculated 6400 as the loss

    (designed for 15 Deg outside/70 in)
  • Formerly
    Formerly Member Posts: 78
    Wonderful. This will enable me to have more choices. Anyone have any suggestions between going Viega FostaPex or Uponor MLC? I have a Ridgid RP 200-B and would have to purchase a head for either direction anyway. I have to buy a head either direction, so all in all Uponor actually winds up being cheaper by a few hundred in the end...but a bit more labor.

    Also, I am 90% certain the heads are all cross compatible, as long as you make sure you know whether to go compact/standard. Anyone have any suggestions?
  • Formerly
    Formerly Member Posts: 78
    So, bought both heads, will return whichever one doesn't work. I will report back.
  • Formerly
    Formerly Member Posts: 78
    edited April 2016
    I've decided I will heed the advice of Hatterasguy and keep the primary only system. I am going to use a grundfos alpha on autoadapt with 3 zone valves controlled by a taco relay box, and I will stub out and appropriate for a future DHW and future ModCon (I like that lochinvar!) When that time comes, I will get a 0-10v circulator for the primary and switch the grundfos to the DHW. Also, just in case, I will pipe the supply/return in such a way that if worst case scenario I can cut a section out of both and insert a hydraulic separator. Bunch of stuff is on order so it will be a little bit of cleaning to prep my basement for the onslaught!
  • Formerly
    Formerly Member Posts: 78
    I can not thank you enough for your time and patience!
  • Formerly
    Formerly Member Posts: 78
    Ahh forgot about that - boiler protection valve - on it. thanks!
  • Formerly
    Formerly Member Posts: 78
    Minor update - going with FostaPex since the Uponor Jaw does NOT work on the Ridgid 200B. Also, picked this valve (wanted brass, and like the unions)
  • Formerly
    Formerly Member Posts: 78
    Hatterasguy, as far as the boiler protection valve, I chose 140 deg as the bypass temp. Sounds appropriate for a CI boiler right?
  • Formerly
    Formerly Member Posts: 78
    OK, I have most of the parts in, and I am having trouble choosing a layout. At first, I thought I would be putting the circulator on the supply after the expansion tank/freshwater valve pushing into the boiler protection valve, but after talking to hot rod through email, he implied that while this layout will work, it would be better to position the circulator so that it is pulling through the boiler protection valve on the return side. This means I need to move the expansion tank ideally, right? Anyone have any advice?
  • Formerly
    Formerly Member Posts: 78



    Rough layout, hope its clear enough - anyone see a problem with this design?
  • njtommy
    njtommy Member Posts: 1,105
    edited May 2016
    Pump needs to be moved to the return of the boiler. So the valve would be on the suction side of the pump.
  • njtommy
    njtommy Member Posts: 1,105
    .
  • Formerly
    Formerly Member Posts: 78
    edited May 2016
    yeah, was getting torn between the way caleffi suggested and the rather new(ish) "golden rule" of "pump away." This is more like what it should be?:


  • njtommy
    njtommy Member Posts: 1,105
    Yes nailed it.

    The Golden rule is to pump away from the expansion tank.
  • Formerly
    Formerly Member Posts: 78
    awesome. thanks!!!
  • Formerly
    Formerly Member Posts: 78
    edited May 2016
    just because I am curious, my mind says that theoretically the circulator could be on the supply without changing the performance of the thermostatic valve as long as it is before the Tee, as in the first picture. The location of the actual thermostatic valve on the return side is the key factor - it is the thing regulating the flow of water, regardless of where the flow is created. Simply moving the circ on the other side of the boiler (supply side) shouldn't change the way it works in any way, unless someone could educate me on something I am missing, right?
  • Formerly
    Formerly Member Posts: 78

    I'd put the circulator on the supply side as the pressure at the valve is increased because you don't suffer the pressure drop through the boiler. Now, it might not be significant on the CI boiler, but I wouldn't dismiss it because that boiler has very little water volume.

    No readily available info on that boiler regarding pressure drop at specific flow rates.

    so you would advocate the first picture hatterasguy?