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Burnham oil burner not heating both zones

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snickers
snickers Member Posts: 13
edited January 25 in Oil Heating

I have a 35+ year old Burnham boiler that had been working well. It is not heating one of the zones. Temperatures are freezing cold with blizzard on the way. I am hoping to troubleshoot. It is set to automatic. Oil tank full. The filter is relatively new. Thermostat is 1 year old and basic. It may be zone valve. I just switched to open and heat pipe heated up. Any suggestions?

Comments

  • bburd
    bburd Member Posts: 1,282
    edited January 24

    Is this hot water or steam?

    How many thermostats do you have? Usually there is one per zone.

    What exactly is set to "automatic"? A switch on the thermostat?

    —
    Bburd
  • snickers
    snickers Member Posts: 13

    bburd: hot water. Two zones I just opened the zone valve on the one that had cold pipes. It is heating up now. I think I might have found it. But why in open position? Thermostat room temp is currently 50 when set to 68

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  • snickers
    snickers Member Posts: 13

    I meant the zone valve

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    switch from open to closed?

  • snickers
    snickers Member Posts: 13

    bburd- Good news. The heat is on now in both zones. Thanks.

  • bburd
    bburd Member Posts: 1,282

    Most likely the zone valve power head has failed, or it could be a problem in the thermostat circuit or zone valve end switch circuit. You can check these things with a multimeter if you are handy with electricity. If not, it might be best to call for service.

    For now, since the weather is very cold, I suggest you leave the zone valve manually opened. That zone will heat at the same time as the other zone, so you should be protected from frozen pipes.

    —
    Bburd
    snickers
  • snickers
    snickers Member Posts: 13

    bburd- Thank you. I will leave it manually open. It is extremely cold outside. Yes, frozen pipes was my concern. Thanks. I have a multimeter and will check.

    bburd
  • snickers
    snickers Member Posts: 13
    edited January 25

    BBurd: The heat is on but very slow. Went up from 48 degrees F to 55 in 12 hours. Leaving the switch to open works but very slow. Filters new last year. We checked the zone valve 3 wires (red, white and green) with a multimeter and it appears to be working same as other. Zone 2 upstairs is working beautifully. The boiler heats and then shuts off, even when it doesn’t get to set point. But I am happy that it is warmer- we just prevented pipe bursting. 55 and slowly rising. Should I buy a new zone valve at some point? They predict we will have about 16 inches of snow starting this afternoon and frigid cold so may need to wait. I so much appreciate your help.

  • mattmia2
    mattmia2 Member Posts: 16,117

    check if there is 24vac on the zone valve motor terminals when the thermostat is calling for heat. is the valve open if there is? if there is but the boiler is not firing, check the end switch terminals, it should be 0 vac because they should short together when the valve opens.

    the other zone that is cold will be slow to heat with the valve open but no call for heat, it will only heat when the other zone is calling and that zone is up to temp so it is only calling for heat to make up for loss, not to increase the temp. the system may only be able to provide the heat lost, not also increase the temp if you are at the temp the system was designed for.

    bburdsnickers
  • HVACNUT
    HVACNUT Member Posts: 7,326

    Can you post a picture of the zone valve? Is it this?

    Screenshot_20260125_053911_Samsung Notes.jpg

    If so, you likely just need a replacement head. Double check the plunger moves freely and there's no corrosion around the pin.

    I dont think a 7° rise in 12 hours with frigid temperatures is too bad. Its playing catch up.

    snickers
  • snickers
    snickers Member Posts: 13
    edited January 25

    Yes. It is a taco that looks like that. Ok. Replacement of

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    the head. I will check it. Here is a photo.

  • snickers
    snickers Member Posts: 13

    mattmia2- Thank you. That makes so much sense( It is only ‘calling for heat when other zone calling’ and ‘only calling for heat to make up for loss.’ ). That explains why it is not cranking for heat when it is not to set point. We will try to check the end terminals.

  • mattmia2
    mattmia2 Member Posts: 16,117

    that heat motor type zone valve has a common terminal between the heater for the heat motor and the end switch so you test from that common terminal for 24vac to open the valve and shorted terminals to call the boiler.

    snickers
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,800
    edited January 25

    Your Taco 570 series zone valve can cause the best of plumbers and electricians to go batty trying to understand how they get it to work with only three wires.  The motor needs 2 wires and the end switch needs 2 wires.  That adds up to 4 wires.  So don't feel bad if you don't understand what is happening.  You are not the only one!

    What you have described is a classic problem when a power head goes bad.  Replacing the power head with the identical power head is the best repair for you.  You don't even need to leave the house to get one.  You can get it at SupplyHouse.com if you have a computer or smart phone.  (I guess you do if you are on this forum)

    Click here for the info: Taco 555-050RP

    Take a picture of the wires before you take the wires off the old power head.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    snickers
  • Intplm.
    Intplm. Member Posts: 2,932

    @snickers When you do change that power head, make sure you turn the power off to the boiler. If you forget, you will blow the power head and have to start all over again.

    snickers
  • hot_rod
    hot_rod Member Posts: 27,116

    the speed at which it catches up depends mostly on outdoor temperature and amount of heat emitters you have

    If the boiler cycles off when both zones are heating you have more than enough boiler capacity

    It is not unusual for that ZV motor and the valve piston operation to be comprised

    Buy an entire new valve do you have both components if needed

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    snickers

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