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Help with System Design WM Aquabalance Boiler

xjazzwreck Member Posts: 7
edited September 2021 in Radiant Heating
Hello, long time lurker, first time posting! I've been reading and learning a lot from you pros so thanks for the help through the years!

I am getting ready to replace our old cast iron boiler with a more efficient unit and would love some input on my layout before I start putting it all together in a week or so.

The main parts of the system are;

-Weil Mclain AquaBalance AB-80-H (I also purchased the factory near boiler manifold with circulator isolation and closely spaced tees.)
-Boiler circulator is a Taco 0015e3 ECM
-House circulator is a Grundfos Alpha 2 15-55F that' i'll run in delta P mode
-Zone valves are Taco sentry

This is a 3 story (plus basement) townhouse in Brooklyn, NY. The boiler is in the basement and there is currently one zone per floor and I will be adding a 4th in the basement. I'm thinking I will leave the end switch disconnected on that 4th zone so it only gets heat when another zone is calling.

Some of my bigger questions are;

1. Is the placement of the expansion tank correct? On a lot of diagrams I see it on the return, but the WM manual (LINK) says "It is highly recommended that you locate the air separator and expansion tank as shown in the suggested piping drawing pg 39-41"
2. I know I need purge valves on each zone return but was a bit lost on where else to place purge valves for bleeding and filling the system. Does what I have work?
3. The manual shows the Zone Valves on the return but I placed them on the supply, is that okay?
4. I was unsure of where to place the Dirtmag but think this is correct here on the house loop return.
5. Besides the closely spaced tees are there any other locations where I need to be careful with pipe spacing? i.e. on either side of the circulators, spacing between zone tees, spacing around zone valves etc?

And then I have a few questions if anyone is familiar with this boiler...

1. Can you limit the high fire on this?
2. Can you adjust how quickly it goes to high fire? I think I saw a P02 adjustment in the manual that may help here but not sure.

Thanks in advance for any help/advice/criticisms!


  • mattmia2
    mattmia2 Member Posts: 9,469
    edited September 2021
    This will answer most of your questions.

    It looks like you have more than enough valves to purge. A valve to block the flow in the loop near the boiler and the zone valves are all you really need, with the water feed and a drain on opposite sizes of that valve so you can force the water from the feed out through each zone sequentially using the zone valves.
  • xjazzwreck
    xjazzwreck Member Posts: 7
    Thanks for the response and a link to that article, lots of great information on there. It looks like the Air sep is in a good spot, still not sure on the dirtmag.

    I am having a hard time understanding how the purging idea translates to a Primary/Secondary setup... i.e. can I take that same concept of purging it all through the boiler with each zone when it's piped P/S? Also, they show the SOVs on the supply after the zone valve... should i move my SOVs from the zone return to zone supply?

    Thank you!
  • mattmia2
    mattmia2 Member Posts: 9,469
    edited September 2021
    Everything you wanted to know about air and dirt separation:

    Other Idronics articles are great too. The return from the system is a good place for dirt separation because it mainly will be the iron oxides from your CI radiators and steel piping, it will trap it before it gets sucked in to the HX or circulator which is where it causes problems.(er, I guess you didn't say what your piping and radiaiton are. If it is ferrous there will be stuff to trap, if it is all copper, not so much).
  • xjazzwreck
    xjazzwreck Member Posts: 7
    Amazing, thanks so much! I think it will be helpful there, we have cast iron radiators on one floor and slant fin on the rest.
  • xjazzwreck
    xjazzwreck Member Posts: 7
    Update: I started the installation and would love any input before I start pressing/finalizing things tomorrow. It's still WIP and I need to secure some more pipes and run the make up water/expansion tank. But if you see any issues please let me know so I can correct it before it's too late. Thank you!

    EBEBRATT-Ed Member Posts: 15,345
    Looks like it will work!
  • xjazzwreck
    xjazzwreck Member Posts: 7
    Thanks! I just looked at the photos and noticed the plumbers I hired to do the gas did not put in a drip leg.. will have to have them correct that. 
  • xjazzwreck
    xjazzwreck Member Posts: 7
    Here's an almost final photo of the install, it's working great with one issue... this may just be because it's shoulder season, but with a long call for heat it seems to cycle on and off too quickly.

    Once set temperature is reached it shows "d2" and continues the call for heat until the water temperature gets low enough to fire again. This is the problem, it seems to go right to high fire and it heats the water up in less than a minute and then flame out and back to d2.

    Any thoughts on this? Shouldn't it be starting with a low fire/modulation in that case?

    Thanks in advance for any help!