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New Peerless 63-04 Cycles on Pressure

OleksiiC Member Posts: 12
After replacing cracked Utica with Peerless 63-04 I see the boiler turned off by pressure (> 2psi). When that happens, the last radiator is still cold and then i hear quite loud bang. High pressure was never the case for the old boiler (same size, EDR calculated by two independent plumbers). There're only two differences in old vs new setup:
1. Cyclegard that comes with Peerless is turning off burner every 15 mins for 60 seconds. The pressure starts rising after two cyclegard cycles
2. New return and main vent installed on the one of two mains

The question is, could the #1 be the root cause or is it definitely #2? The plumber will come next week, but I want to have some thoughts before.


  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    edited May 2021
    Probably neither, but possibly #2 if the new main vent or the old main vent are failed closed.

    But the most probable answer is that it's oversized. How did the plumbers calculate the size of your new boiler?

    It's not #1. The cyclegard if anything will reduce cycling because it introduces cycling of its own allowing pressure to drop.

    What is "the last radiator"?

    The bang says there is water collecting or getting pushed where it shouldn't be
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    If you look on the ratings plate on the boiler, you will see a “steam square feet” line. That value must equal or be very close to the total EDR of the radiators, (also expressed in square feet of steam).
    Your plumber may have been confused and added in a 30% increase in sizing the boiler.
    Post some picture of the boiler piping, so we can make sure he hasn’t made some other error.—NBC
    Brent H.
  • BobC
    BobC Member Posts: 5,477
    Has this system been skimmed? Skimming removes any oils introduced into the system by the new boiler and pipes. Dirty boiler water can cause all sorts of abnormalities in a system and that's the first thing I'd look for.
    Is the water in the sight glass reasonably steady and is it clear? If it's green or yellow they may have added a chemical to clean the boiler, that is usually left in for maybe a week and then the boiler is fluched out and refilled with clean water (sometimes a treatment is added to control corrosion but that usually results in tinted water depending on the chemical used.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    JUGHNE Member Posts: 11,058
    Could your old boiler been leaking (at or above the water line) for some time, steaming up the chimney and not building pressure to shut off on high pressure?
  • OleksiiC
    OleksiiC Member Posts: 12
    Thank you all for such quick responses. So,
    1. EDR calculated is 420, boiler is 458 sqft. It's Peerless 63-04
    2. Last radiator is the last one connected to the main. However, today all the radiators were hot.
    3. The system has been skimmed, no oil film is now visible when skimming and water level is not fluctuating
    4. The old boiler was cracked and the white smoke was going out of the chimney.

    I had to turn it on today because of great weather in NJ. All the radiators got hot, pressure started going up after ~45 mins. The pressure gauge shows 0 all the time, but then goes up to 1.5 psi quickly. The water in the sight glass also became very far from clean.

    Is the boiler oversized or could that be just dirty return?

  • EzzyT
    EzzyT Member Posts: 1,295
    I would question the possibility of lack of skimming of the boiler and the where the two mains take offs come off of the single riser. They should be coming off of the header separately instead of how they currently are plumbed.
    E-Travis Mechanical LLC
    EBEBRATT-Ed Member Posts: 15,510
    What @EzzyT said plus you may not have enough venting
  • OleksiiC
    OleksiiC Member Posts: 12
    the situation is getting more interesting. The main vents started spitting the water. Looks like new return pipe is the next step (the water returned to the boiler w/o any issues, but probably it got clogged after all the adventures) 
    EBEBRATT-Ed Member Posts: 15,510

    If the boiler was not skimmed it will throw water up into the main. As @EzzyT mentioned both supply pipes should come down into the new boiler header separately. For a steam boiler to work it must be clean internally and piped right.

    How it was before means nothing
  • OleksiiC
    OleksiiC Member Posts: 12
    Do you by any chance have a good photo of how the piping should be done or point me where the second takeoff can be installed in this diagram? 

  • neilc
    neilc Member Posts: 2,700
    your 2 steam supplies should connect between 8 and 10 in that diagram
    known to beat dead horses
    EBEBRATT-Ed Member Posts: 15,510

    It can come off at #6, #8, or #10
  • OleksiiC
    OleksiiC Member Posts: 12
    Is that possible to get any manual or diagram that shows proper two mains connection? I've been told, that it's done according to manufacturers reco.
  • dopey27177
    dopey27177 Member Posts: 887
    Te second stem main should come off a T placed at 6,8 or 10.
    The second steam main should have its own vent to remove air from that part of the steam supply.

    In addition skimming a new boiler could several skimming cycles. Also you need to drain the returns each time you skim the boiler.

    Remember much of the dirt that comes out of the boiler drains into the return piping.

  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    OleksiiC said:

    Is that possible to get any manual or diagram that shows proper two mains connection? I've been told, that it's done according to manufacturers reco.

    Your diagram is correct, as far as it goes, but it assumes there's only one main branch. Additional branches need to have their own risers, and these should arise from the header. Here's a picture of a header that feeds two mains.

    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    edited June 2021
    I agree the piping isn't 100% correct, but I doubt that is causing a pressure rise to 1.5 psi.

    Can the OP provide a table showing the timing of these events starting from a normal call for heat?

    1. Time to steam at header
    2. Time to steam at main vent
    3. Time to steam at first floor radiator(s)
    4. Time to steam at 2nd floor radiator(s)
    5. Time to .5 psi
    6. Time to 1.0 psi
    7. Time to 1.5 psi (should cut off at this time)
    8. Time to cut-in
    9. Repeat logging of 7 and 8 until thermostat satisfied (I know it's getting hot so you might have to do this test in the fall unless like me you really like to know answers).

    Note these times might not all come in the above order. I just listed them as I thought of them.

    I suspect that the boiler is simply oversized. Perhaps the EDR was improperly calculated, or some radiators are shut off at their valves, or there is no main venting. But the times above should expose that.

    Edit: oops I saw I replied to this thread already. I was away for a week rock climbing in Idaho so I am out of touch. I still think these times should help find the problem.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,215
    I would not worry at all about the fact that each steam main is brought separately into the header. This is never done on commercial systems since it would be nearly impossible. A Peerless boiler in that small size is probably producing more usable steam than most typical Utica installations of the same size. In addition, you are not loosing steam up the chimney so there is more steam to build pressure. Cleaning is important, it typically takes a full heating season to get a new boiler cleaned out and the system cleaned out with it.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • OleksiiC
    OleksiiC Member Posts: 12
    edited June 2021
    The EDR was calculated by two independent plumbers and was right in between of 63-04L and 63-04. But we were able to get 64-04 only, because of shortage of everything.

    After full day of skimming/cleaning cycles:
    1. All the radiators were hot
    2. Both main vents worked fine

    However, after all the radiators become hot and vents closed (~40 mins from cold start), the boiler shuts off by pressure and doesn't turn on again ~10 mins. The longest cycles i had with the previous boiler were ~60-70 mins in the coldest days.

    So seems like it all make sense (because now boiler doesn't heat the chimney and nearby cedar), doesn't it?