Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Peerless PF850 High gas pressure switch trips

Case1
Case1 Member Posts: 2
We installed several PF850 boilers on different projects, and are experiencing high gas pressure switch tripping out.
One of the projects we have installed a lockup gas regulator and set for 6"WC. The high gas pressure switch factory set for 13.5" WC will trip randomly sometimes will work for several weeks, before the next time it trips out.
Another project is on a Low pressure gas service only has incoming gas pressure of 5"WC and the High gas pressure switches trip out on this installation as well.
Anyone else having these issues, what have you done?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,010
    I am not famillier with that boiler but I'll take a good guess.

    It's probably shutting down on high fire. Looks like the gp switch is mounted between the source of supply and the gas valve. When the gas valve closes the regulator can't react fast enough so the pressure spikes a little tripping the switch. If you can get the boiler to modulate back to low fire before it shuts down you will have better results.

    Also, it is unusual to have the high gas pressure switch mounted upstream of the gas valve. They are usually downstream of the gas valve at the burner location.

    Have you called Peerless on this? I would put some pressure on them. I have never seen a hi gp upstream of the gas valve
  • ScottSecor
    ScottSecor Member Posts: 547
    We've installed about three dozen PF-850 through PF-1500 series boilers (all natural gas, none propane) in the last eight years. Some systems are barely maintaining 6" w.c. inlet pressure to the boilers, some hold steady around 8" w.c. incoming pressure and on at least one job we used step down pressure regulators that drop 2psi down to 8" (one regulator for each boiler (four PF1000 and two PF-850 at the same site).

    We have never had to reset the low or high gas pressure switches on any of these boilers. I suspect you may need a lock-up type regulator if your seeing pressure creeping up on occasion. On the other hand is there any chance the regulator vent is blocked and allowing the pressure rise up? Definitely call Peerless asap.
  • Case1
    Case1 Member Posts: 2
    Thanks for your reply. This last job we did install a lockup regulator and still have the issue with occasional trips. We set it up at 10" WC after another call back we set it up at 6" we have witnessed a quick spike on high to low fire.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,010
    @Case1 , I would double check the regulator sizing carefully on the one you installed the lock-up reg on. If your between sizes smaller is usually better. I have seen the correct reg with too large of an orafice cause "hunting"

    Are the hi gp switches installed upstream of the gas valve? I would be curious to know why Peerless does this. Hi gp switches are usually installed at the burner
  • ScottSecor
    ScottSecor Member Posts: 547
    https://www.peerlessboilers.com/wp-content/uploads/2017/12/CatLit_PUREFIRE-Comm_web0617.pdf

    Above is a link to a photo from the PB website, notice the low and high gas pressure switches (blue). This is typical for all of the larger Purefire series (PF-850, 1000 and 1500).
  • ScottSecor
    ScottSecor Member Posts: 547
    https://www.weil-mclain.com/sites/default/files/field-file/WM1707_BRO_043_SlimfitWeb.pdf

    If you look good at the link above, you'll see Weil McLain does the same thing with regard to the location of low and high gas pressure switches.

    I never really thought about it, but I suspect due to the Dungs style gas valve you cannot locate the gas pressure switches after the gas valve.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,010
    @ScottSecor If I am not mistaken most all the new gas valves Dungs included have various tapping for switches, pressure checking etc. In fact I have seen several where the pressure switch mounts directly on the side of the valve with an "o" ring...no 1/4" nipple.

    I suspect the mounting of the High GP on the inlet piping has to do with the negative pressure on the outlet side of the valve from the combustion air blower.

    Problem is with it on the inlet the GV slams shut and the regular can't catch it fast enough you trip the HGP