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Boiler install questions


Thanks for your response, here are a few answers to your Qs...

Yes I do get good heat, seems to heat evenly, the only issue is the 2nd floor but the issue is probably due more to the size of the elements in the rooms and the location of the Tstat. In other words, Tstat is located in the MBR, which is ~300 sq. ft., faces south (lots of sun exposure through double windows) and has 20' of element. The two other rooms on this floor are BR roughly 140-150 sq ft each, and they have 11' and 14' of element, but get little to no sun exposure. Those 2 rooms are much colder at night (the doors are closed then) by 5-7 deg F. At first I thought it was air trapped in the system, but I can feel heat across the elements and the pipes get very hot, seems to have good flow. This is why I figured to zone these two rooms seperately.

Should I consider moving the circ to the supply side after the xtank? Any idea why the installer would put the circ on the return side? Would the system run better with the circ on the supply instead of the return? I have seen another system installed by a different installer that had circs instead of ZVs and the circs were all on the return side, seems there's a reason for this but I haven't been able to find out why...

My current system doesn't seem to have a balance valve, where would the balance valve go?

What do you mean by 'bullheading' the T tap? My plan was to install the T after the 3/4" ZV, but each loop off this T would have it's own return direct to the main return line (1-1/4") is this OK or should I split the left and right into 2 zones w/ individual ZV?

The indirect Superstor has 1" boiler supply & returns... if I pop an 007 circ on this zone instead of a ZV will I be OK? Do I need a check valve with this setup?
I currently have the DHW set up as a priority zone on the controller...



  • Steve Jacques
    Steve Jacques Member Posts: 5
    boiler installation questions

    OK this might be a little long winded, I'll try to condense as much as possible:
    The setup:
    Bought the house 6 years ago, found out the house was an auction house. Boiler was missing, the flippers installed an old boiler they had lying around.
    I had the boiler replaced 2 years ago by the cousin of a friend of a friend... did a pretty good job but they sized the new boiler based off the old boiler, which was selected by availability, not sized to the needs...

    The System:
    House is 27 yrs old, new siding w/tyvek wrap, new attic insulation, 3 floors, ~800 sq. ft. per floor. 1st and 2nd floors finished, i'm in the process of finishing the basement.
    Smith cast iron boiler, Series 8 (90k Btuh) running at ~170 deg F
    Taco 007 circulator (came with boiler), installed on the return feeding into the boiler
    Currently 4 zones (Taco 571-2 zone valves), one for each floor + one for 45 gal superstor
    Taco ZVC404-EXP control, Superstor on the priority
    The rest is typical, expansion tank, spirovent, reg, etc...

    The research:
    Used slantfin to try and calc the heat loss by room, by floor, etc... slantfin shows a total house heat loss of ~56k Btuh, give or take based on factors...
    I did a DETAILED pipe run for each zone(floor), basement had ~226 ft of 3/4" piping, of which 19' was element, 1st floor ~292' of 3/4" w/ 34' element, 2nd floor ~364' of 3/4" w/48' of element
    Supply and return manifolds are 1-1/4" black pipe

    OK here goes...
    1) All the research I've done shows the circulators on the supply not the return, I imagine they installed the circ on the return to keep the pressure spikes down when a zone valve closes? Would you suggest I leave this as is or should I think about moving the circ to the supply side after the exp tank?
    2) Also, since the circ pumps into the boiler, and the expansion tank is on the outlet of the boiler, does this violate the circulator after the expansion tank rule? I assume there's some pressure increase when the return water is heated in the boiler?
    3) There's no balance/diff valve in the circuit, do I need one?
    4) Is an 007 circ capable of handling this system? When sizing a circ, do you size for the worst state, i.e. all zone valves open at the same time?
    5) The second floor is all bedrooms, thermostat is in the master BR which faces south and gets a lot of sun exposure. It also has 20' of element, but it's the last room on the 2nd floor run. However, the 2 kids rooms are much colder than the MBR (by about 5-7 deg). Kids rooms are 11' x 13' and 11' x 14', with 11' and 14' of element respectively. I was planning on adding another zone for them with their own Tstat, is this the best solution? I would need to upgrade my controller as I'm out of zones.
    6) I was thinking of putting a circ on the superstor zone, which would free up the zone valve for the new kids room zone, is this the best way to go? If so, what size circ would do for this? The pipe is 1" copper to and from the Superstor, and there's only about 4-5' for supply and ret.
    7)1st floor piping runs all over the place, basically it runs about 75' to the left of the boiler (bath and left side of LR) then crosses back over the boiler and runs another 107' to the right (right sie LR, dining rm, kit, return). 1st floor is pretty much open space, I was thinking of splitting the supply (after the 3/4" Taco ZV) with a 3/4" tee to the left and right sides, each side would have it's own return to the 1-1/4" manifold, is this OK to do? Any better suggestions?

    If you're still with me, a BIG thanks for reading all of this! I wish I had done all of this research when I first had the boiler installed, but the old boiler kicked out in November, not much time to do research and plan it out when there's no heat in the house!

    Thanks in advance for looking at this!
  • Timco
    Timco Member Posts: 3,039

    1&2..Circ should pump away from exp tank to keep air moving through the system to be scooped out. Typical is water supply feeds into bottom of Spiro vent, and x-tanl tees off that feed line. This is the first item on the supply side. Then, circs. Has nothing to do with spikes. 4 zones...maybe. does the system heat evenly? Do you have 'water velocity' noise with one zone on only? With a 007, likely not. Circ is sized for all zones on at once, and when just one is on, there is sometimes too much flow and the balance valve helps relieve the 'oversized' circ as it is when just one ZV is open. Sometimes you have a large circ with a dozen ZV's. then you would need the diff bypass. 007 is a smaller circ, but should do your job depending on piping issues. Are you heating well / evenly? If you 't' the supply, try to balance the loads so one branch does not suffer. Do not 'bullhead' the t. tap off the main line. Your indirect will have flow (GPM) requirements. Some want 11/4 pipe. I used a 007 on one I just finished and it is fine. An indirect can be run from a ZV or a circ. I prefer a circ, right off the supply first to get the best HW. Put it on priority by using a Taco multi-zone controller w/ priority for your zoning / DHW.

    Just a guy running some pipes.
  • Timco
    Timco Member Posts: 3,039

    Before you go too far, I would read Dan's book...pumping away. It has almost everything you will need. The t-stat will govern the zone, and if it is in a extra sunny room, there you have it. You can move the t-stat or add one as you said. Very common to see circs on return...most boilers shipped that way. Unless you learn better, seems like a good idea if that's where the mfg put it. Put the setup as I described...air removal w/ x-tank & feed, then cic(s) then manifold for ZV's. balance bypass goes on the end of the ZV manifold tot he return. Do not pipe into the center opening of the t. pipe into a side of it, and 'Y' out from there. If the runsa are not super long, and balanced, you can split, but if you use seperate ZVs, you can use seperate t-stats as well. Better that way. Have the 007 for DHW come off the manifold after the air remover, but before the system circ so it gets HW first. A check is needed upstream of your return connection on the return manifold to prevent migration. You may want a pro to bless this work you are heading into...I would hate to see you without heat...sounds pretty advanced for diy'er.

    Just a guy running some pipes.
  • Steve Jacques
    Steve Jacques Member Posts: 5

    I'll order Dan's book... I agree this might be advanced for a DIY'er, my problem (I hear this a lot from my wife) is that I'm an engineer and former auto mechanic, so really nothing is off limits to me provided I fully understand what I'm doing... which is why I posted here. I'm somewhat of a perfectionist, so I'm always looking to improve things...

    That said I really don't want to deviate much from the setup I currently have unless there's a good reason (safety, eficiency), I just want to make sure it's a sound setup and the changes I plan to make won't negatively impact the system.

    So, if I read your message correctly, there's no problem with the circ on the return side, I can leave it there? currently I see no flo check in the system, probably not needed because of the zone valves, is that correct? Do you see any value in moving the circ to the supply side and setting up with a balance bypass, or am I just fine as is?

    Also, if I use a circ for the DHW, do I now need to install a check on just this circuit? does the check valve go on the return line just prior to entering the return manifold?

    I will try to split the 1st floor circuit with a T as you described first, if it doesn't work well I'll add a new line with a ZV... point here is that I only need 1 Tstat as the 1st floor is relatively open space and only 800 sq. ft., if I end up using 2 ZV could I parallel the Tstat to 2 inputs on the Taco zone control?

  • jeff_25
    jeff_25 Member Posts: 110

    2nd floor bedrooms try closing some of the baseboard in the masterbedroom and make sure it open in the others also make sure the fin is clean and no furnacer is in front blocking the baseboard also if bed is to close the bedding can block it good luck jeff
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