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Burnham boiler

cgriff Member Posts: 1
I have a Burnham boiler… My baseboards are hot in the summertime when the thermostat is set at 50. I also have a boilermate, so boiler runs in the summertime to heat water. But the boiler is running even when boilermate is up to temp. 
I turned ball valve off before circulator. This stops boiler from heating baseboards. Can you give advice?…my thermostat is new. This was a problem with an old the thermostat also.


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    I think you or preferably your service provider, are going to need to do some diagnostics, first on the low voltage wiring, then on the controls. You don't want to close that valve if there's a circulator on that circuit running.
    My initial thoughts are maybe a shorted low voltage wire, and if that checks out, I'd check out the aquastat.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,952
    edited August 2022
    Sounds like phantom flow - also called gravity flow. When the boiler heats up to heat the Boilermate, the hot, buoyant water will flow up past the pump and through your baseboards even though the pump is off. Install a check valve directly after the pump or on the supply side leaving the boiler.

    Here is a recent thread on the same subject:

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    @Alan (California Radiant) Forbes I initially considered that until the OP said "But the boiler is running even when boilermate is up to temp...
    Alan (California Radiant) Forbes
  • Steamhead
    Steamhead Member Posts: 16,736
    @cgriff , did the boiler also heat your hot faucet water before the Boilermate was installed?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    EBEBRATT-Ed Member Posts: 15,353
    Could be a bad check valve or flow check depending on if the pump is running or not
  • pedmec
    pedmec Member Posts: 943
    is that a triple aquastat mounted on the front. you can find the model number by removing the front cover and looking on the underside.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,618
    edited August 2022

    @pedmec , @EBEBRATT-Ed , & @Steamhead are all on the same page as me with this thought.

    Prior to the Boiler Mate water heater you may have had what is known as a tankless coil for Domestic Hot Water (DHW). It is hard to tell with the pictures you posted because that boiler had the tankless coil on the left or right side, where we can not see, in those pictures

    If that is the case, the Boiler Mate installer should have checked several items along with the new water tank.
    1. Check if the control could be made to offer "Cold Start" for the burner. This means that the burner only operates with a call for heat or a call for hot water. (if you has a tankless coil the boiler previously maintained a rather high minimum temperature for the tankless water heater)
    2. See if there is a flow check valve or flow control valve at the top of the supply pipe (vertical pipe) indicated in the photo.
    3. Be sure to add a flow control device like a flow check or flow control valve or an internal flo-chek in the new DHW circulator pump.
    4. Do a system check to see if the boiler would have an acceptable sequence of operation in order to prevent heating of radiators when there is no call for heat.

    Please answer our questions so we can guide you in the proper direction.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics