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.

Help! Problem with Burnham MPO temperature guage and pressure. Scratching my head??

MCarpenter
MCarpenter Member Posts: 12
Went to customer's house. Relief valve leaking. Brought boiler to 15 psi. Tested Water feed, expansion tank, Superstore coil okay. Ran the boiler everything okay. After the third cycle tridicator guage temperature reading 260 and aqua stat at 140 water pressure of course building up to 30 and boiler blows off. I change aqua stat of course thinking boiler running too hard. Still doing the same thing. Put old aqua stat back on and decide to change expansion tank simply because it was under sized for house. Boiler temperature guage and aquastat working in synchrony now. Boiler pressure 15-22 psi. Has been monitored all night and relief valve not blowing off. Boiler pressure got to 30 first thing this morning during the first cycle but came back down soon after. This one is beating me up pretty bad mentally. Pressure on house is 70 psi. Put guage overnight on main. Advise anyone???

Comments

  • RJ_4
    RJ_4 Member Posts: 484
    expansion tank

    Do you have a diaphram style tank, if so have you checked to see if it still has the air charge, you can use a tire guage, should be at least 12psig.   the other thing I would check is the fill valve, most have a small strainer you can remove and clean. If the fill valve is old and never cleaned the valve could be rusted and corroded internally, this could cause valve problems with internal valve parts causing valve to overfeed.   The fill valve is commonly overlooked.
    RJ
  • Steamhead
    Steamhead Member Posts: 15,330
    If this is the original MPO design

    where the aquastat is on a manifold above the boiler block, check to see that the circulator is running as it should. Also, this boiler MUST NOT be wired so it maintains temperature when there is not a call for heat. The aquastat doesn't always sense the proper boiler temperature unless the water is moving past it. The instructions for this boiler are very clear- the burner should never fire unless there is a call for heat and the water is moving thru the boiler.



    I ran into one a few years ago that was maintaining temperature.... saw the gauge rising past 250 degrees even though the aquastat was set to 180. I shut it down and got out of that boiler room until it had cooled. Then we rewired it so the burner would not fire unless there was a call for heat.



    When I asked the Burnham rep about this, his response was similar to mine- the original installer did not follow the instructions, which proves once again that you can't fix stupid!
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • MikeL_2
    MikeL_2 Member Posts: 369
    immersion well problem

    We had an issue with a pair of MPO's overshooting the aquastat set point by 100 degrees. Both wells had an undersized drilling that prevented the sensing bulb from full insertion.......................
  • Steamhead
    Steamhead Member Posts: 15,330
    Was this

    while the circ was running?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • MikeL_2
    MikeL_2 Member Posts: 369
    circulator

    Yes, the circulator was running.
This discussion has been closed.