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Help with Peerless FlexHeat Boiler

Lev77Lev77 Member Posts: 15
edited October 2017 in Gas Heating
Hi all,

Thanks very much for reading.
We inherited this fancy setup of Peerless FlexHeat hot water boilers on natural gas, controlled by a Tekmar 268 boiler controller. These boilers supply heating and hot water.
Each of the boilers has its own circulator pump.

This will be the first cold season that we're looking after these boilers.
When the heating kicked on during a cold week (a couple of weeks ago), I noticed that the middle boiler did not turn on. Pressure gauge shows 0, pipes are cold, no gas or flames underneath including pilot.

I downloaded the manual for the Tekmar controller, and ran some tests, also set to Max Heat.

The middle boiler still did not turn on or show any signs of life.

I removed the front covers of all boilers.
First observation was that the middle boiler's gas valve had all this strange white/gray dust on it, and the gas pipes connected to the valve had much more exterior rust than the other boilers.

The box on the right top inside the boiler looks like the pressure control unit. There was current on both poles.
I checked for electricity on the wires inside the boiler and there seem to be electricity running.
There was no smell of gas. The circulator pump for the middle boiler was cold.

For now I shut off the gas and electricity to the boiler, and all the ball valves leading water to/from it.

I suspect the gas valve.
But I'd greatly appreciate help with diagnosing the issue.


  • IronmanIronman Member Posts: 4,092
    It takes a DMM and the knowledge of how to use it to diagnose control and electrical issues.

    Just from looking at your pics, it looks like water's been leaking on the gas valve and burners.

    The control that you're referring to is the aquastat.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Lev77Lev77 Member Posts: 15
    edited October 2017
    Thanks, yes, I think that for a while water was leaking high above this boiler. I found and fixed that leak.

    Aquastat - and that's likely/typically the control that is damaged?
    Is that the component under the pressure control unit?

    I once tested computer boards for a job in the far past. If that's the path to diagnose I might be able to figure things out with this Fluke... any guidance?

    What about the gas valve and all the water effects here? What's the recommendation?

    Thanks again
  • HVACNUTHVACNUT Member Posts: 1,025
    edited October 2017
    Pressure is at 0. Is there a low water cutoff? I don't see one on any of the boilers.
    Commercial, should be code.
    Can't see a PRV either.
    Maybe that boiler was isolated for a reason.
  • Lev77Lev77 Member Posts: 15
    edited October 2017
    Thanks HVACNUT,

    Not sure about LWCO, looks like these hot water boilers are fed directly from the water supply with the ball valves always on.
    PRV you can see on the right side of every boiler, behind the pressure gauge. It's a black pipe.
  • FranklinDFranklinD Member Posts: 369
    Going by the pics, it looks like the isolation valves to that boiler are closed, so I'd guess that it's a leaker (based on the corrosion) and was isolated from the system & shut down.
    Ford Master Technician, "Tinkerer of Terror"
    Police & Fire Equipment Lead Mechanic, NW WI
    Lover of Old Homes & Gravity Hot Water Systems
  • Lev77Lev77 Member Posts: 15
    edited October 2017
    Thanks Franklin,

    Actually I closed all those valves just a few days ago and shut off the electricity and gas to the boiler as well.
    Prior to that all the boiler valves were open and the boiler controller still thinks there are 3 functioning boilers. I'm going to disable the boiler in the controller as well until this is fixed.

    Just to clarify, the boiler doesn't seem isolated and it was not leaking (no water under it ever since I fixed a leak in the water supply pipes running along the ceiling about 1.5 months ago).
    If I open all the ball valves around the boiler, there doesn't seem to be any water movement or leak. My impression is that it's some component inside that's not turning the boiler on but I'm looking for help on how to diagnose the issue.
  • IronmanIronman Member Posts: 4,092
    edited October 2017
    That gas valve MUST be replaced since it has had water damage. It's a Honeywell Smart Valve and you MUST use the exact replacement model. Start there and the refill the boiler and purge it of air.

    It would also be a good time to replace the relief valve due to the age of that boiler.

    There's no pressure control on a hot water boiler, other than the fill valve. Are you referring to the boiler gauge?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HVACNUTHVACNUT Member Posts: 1,025
    > @Lev77 said:
    > Thanks HVACNUT,
    > Not sure about LWCO,

    A low water cutoff should be wired in somewhere.

    looks like these hot water boilers are fed directly from the water supply with the ball valves always on.

    Can't be. There has to be a PRV, pressure reducing valve. It's probably piped near the extrol tank.

    > PRV you can see on the right side of every boiler, behind the pressure gauge. It's a black pipe.

    Those are the relief valves.

    Like @Ironman said, looks like it needs a gas valve. Is it standing pilot?
    Can't see for sure, but are the purple wires at the gas valve burned? By the pilot tube.
    You'll also need to pull the burners, clean them, and clear the orifices.

    Also, the tridicator looks fairly new, but maybe it's bad and there IS pressure in the boiler. Try popping the relief valve and see. Have a new relief valve ready.
  • Lev77Lev77 Member Posts: 15
    Thank you very much @Ironman and @HVACNUT,

    I'll check for pressure in the boiler, replace the gas valve and relief valve, clean the burners and clear the orifices, and take closeup pictures of all the components around and in the boiler so they can be identified. If there seems to be pressure, I'll also change the tridicator.

    What's a good way to purge the air off the boiler?

    I guess once I do all that we'll see if the boiler wakes up or not and take it from there. It'll take me a couple of weeks to get the parts and do this work.
  • IronmanIronman Member Posts: 4,092
    Manually hold the relief valve open to purge air from the boiler.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HenryHenry Member Posts: 777
    Anytime water touches a gas valve, it must be replaced. The pilot assembly also should be replaced. The boiler will not go on if the pilot is not lit.
  • Lev77Lev77 Member Posts: 15
    Hi all again,

    I want to thank you @Ironman , @HVACNUT for your help.
    I replaced the smart valve and safety relief valve, cleaned all the burners and orifices, and the rust of the pipes too. I had to change the pilot tubing because the compression screws were all chewed up.

    Purged the air.
    Turned on everything one by one to check for leaks/ issues, there were none. Woke up the boiler through the central controller, and it came back to life beautifully. This last step was only yesterday.

    Much appreciated!
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