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Oil Heat Problem. Heat won't shut off in zone!!

Post in 'DIY and General non-hearth advice' started by BARTSFAM, Jan 21, 2012.

  1. BARTSFAM

    BARTSFAM Member

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    I hate oil heat, and try to keep it shut off 90% of the time, and rely on my pellet stove, so......

    I have one zone that for the past few days, the register is always warm with the forced hot water heat. I cranked the thermostat down to the lowest, 50 degrees, and still I can feel that the register is warm.
    When I crank the register up to the highest, the boiler kicks on, and the circulator pump starts running, like it should.

    I have two other zones, and those registers are cold. The small circulaltor pump for this zone is not on. The motor is not running, but the pipes are warm to hot.
    The warm water from the boiler is feeding this zone. So, I googled this problem, and alot of people seem to say that some valve is stuck open, but my question is, where is this valve? Is it something I can fix on my own?

    The pipe leaves the boiler, and there is no valve that I can see. Only the pump, and a faucet relief valve.

    Any ideas on how to fix this? Or, do I need a repairman?

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  2. maple1

    maple1 Minister of Fire

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    Post this in the boiler room, you should get some answers. Maybe a mod will move it.

    For now I'll say it might be a stuck zone valve - but some systems only have circs & no zone valves.

    What kind of thermostat does it have? If electronic, try popping the batteries out. Then replace if dead. Likely not the cause but worth a shot maybe.
  3. woodgeek

    woodgeek Minister of Fire

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    if the registers are only warm, it could be a thermosiphon (gravity driven flow). One of my loops did that until I turned the shutoff valve. Is the boiler running a lot, or just turning over every hour or two?
  4. daveswoodhauler

    daveswoodhauler Minister of Fire

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    The zone valve should be close to your boiler, but you are right that its odd that you have at least 2-3 zones with no visible signs....sure sounds like you have a zone valve stuck open...can you post some pics of your setup? (Do you have a finished basement...maybe the valves are behind some ceiling tile or insulation?
  5. BARTSFAM

    BARTSFAM Member

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    To answer the previous posts....No, the boiler does not turn on anymore then usual. The hot water is going into this zone, without the thermostat calling for it. The pump is not on, but the pipe is warm to hot.

    I did attach some pics with crudely drawn arrows, showing the offending zone. The pipe for this zone leaves the boiler, goes thru the pump, and then shortly into the wall/foundation. I see no other valves.

    Attached Files:

  6. BARTSFAM

    BARTSFAM Member

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    I may just shut that yellow valve off if I cannot figure this out, until a repairman comes.
  7. semipro

    semipro Minister of Fire

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    I think Woodgeek nailed it.
    Just shut off the valve to stop the thermosiphon flow.
    And remember to open it if heat is needed. Maybe a note hanging on the thermostat?
  8. EatenByLimestone

    EatenByLimestone Minister of Fire

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    You have a pump on each zone. With individual pumps I don't know why they would install zone valves. It is most likely a gravity feeding system. Older systems were intentionally built to have water heated in the boiler and move under its own power throughout the house. It looks like this is what is happening here, but not intentionally.


    Zone valves:

    http://www.google.com/search?hl=en&...urce=og&sa=N&tab=wi&ei=aMgaT8eHNeHc0QGZiIWwCw

    MAtt
  9. woodgeek

    woodgeek Minister of Fire

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    Probably pretty harmless in the wintertime, as the smallish amount of heat is doing some good. Close the valve in the spring, and open in the fall to reduce standby usage. In my case, the loop was near the thermostat which caused some weird effects.

    If you end up getting it fixed by a tech, I'd love some details....although I am hoping to have my boiler scrapped this year.
  10. seige101

    seige101 Minister of Fire

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    Sounds like you need a check valve on the system to prevent thermo siphoning. This would prevent the warm water from thermo siphoning, but when the pump kicks on it would open and the water would flow freely.
  11. BARTSFAM

    BARTSFAM Member

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    I am going to shut the valve off, probably on Monday when it's in the 40's. I don't want the pipes to freeze. And this is a new house, (7 years old), with a new system.
    What's funny is, two zones have the valves. I can see them. And, I know that one valve was replaced for the same problem before. But, this particular zone, I cannot find the valve in plain view. Does anyone know why the thermo siphoning occurs??
  12. willworkforwood

    willworkforwood Feeling the Heat

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    As others have said, you have pumps and no zone valves. It's important to know if this is really something new, or perhaps just not noticed before - no sense paying for a service call if this is something "normal". Are you certain those pipes had always been cold before? If it really did just start happening recently, then something has changed. It’s possible that the offending circ broke internally, and is allowing flow. But that doesn’t happen very often - these circs typically last a very long time. Any oil burner service done recently? You said that circ isn’t on - do you know that because all circs are off (i.e. no noise at all)? Looks like maybe 3 heat zones and one circ for DHW? If so, has your DHW usage increased? It's possible the DHW could be having a TS or proximity heating effect on the HW pipe. What does the temp and PSI on your oil burner gauge read?
    EDIT
    Sent before you last reply. It's very unusual to have both pumps and zone valves - can you see a make and model on the ZV? Having both in a system would certainly make things much more complicated, and probably the cause of some unusual things happening.
  13. EatenByLimestone

    EatenByLimestone Minister of Fire

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    Gravity... Warm water is less dense than cold water do it tends to rise.

    Matt
  14. BARTSFAM

    BARTSFAM Member

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    The last time this happend, in a different zone, the oil man blamed this thing in the picture. He said that this valve was stuck opened, so he replaced it. The problem is, I cannot find this thing in the zone with the problem......

    Attached Files:

  15. woodgeek

    woodgeek Minister of Fire

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    I have a check valve in my loop, but my service tech said that they often fail open after a few years...and that he would want several hundred dollars to replace it, since he would have to drain and refill/purge the system. Glarg.

    I am inclined to think thermosiphons are quite common in hydronic heating systems--mine increased standby by ~1 gallon/oil per day....all summer long.
  16. EatenByLimestone

    EatenByLimestone Minister of Fire

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    That is an automatic air purge valve. It lets air out if you get any in the line. There should be one off your boiler also. You don't need one on every zone.

    Matt
  17. EatenByLimestone

    EatenByLimestone Minister of Fire

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    I don't see how a vale that lets air out of the system could start/stop your issue. I think he might have been yanking your chain.

    Matt
  18. EatenByLimestone

    EatenByLimestone Minister of Fire

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  19. BARTSFAM

    BARTSFAM Member

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    That's just great to know. Another reason I depend on my pellet stove for heat.....
  20. bjkjoseph

    bjkjoseph Member

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    its called a flow control valve...there is a little ball in there..and when the circulator kicks on its enough to lift that little ball..and let the water flow by...and when the circulator clicks off...the little ball falls back into place preventing the hot from flowing to that zone....my flow control valve is also broken...and i have it on the list...man that list just keeps getting longer and longer.
  21. BARTSFAM

    BARTSFAM Member

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    UPDATE WITH MORE BAD NEWS::

    Last night I went home, and the thermostat on the front of the burner showed 70 degrees, the lowest reading. I activated a thermostat, and the boiler kicked on, and heated up.

    I went to bed, woke up this morning, and there was a puddle on the floor from the overflow pipe that faces downward.

    So, to review: hot water flows to a zone that does not call for it; boiler does not seem to come on automatically unless a thermostat makes it; and water coming out of the downward facing pipe.

    Any ideas?
  22. woodgeek

    woodgeek Minister of Fire

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    Sounds like the aquastat/controller. The running cold would be a fault in the aquastat (assuming you have a tankless coil for DHW, it should never go below 130°F). IF the aquastat is malfunctioning, it might be swinging too high also, which could overpressure the system and blow some water out the relief valve.

    I wouldn't run it like that....but replacing an aquastat is a quick job (I replaced mine myself once). Maybe $200 for the new hardware, less than a hour of labor.

    I think this is independent of the thermosiphon....I've found that a lot of systems if not most are not working as designed, but so long as they deliver BTUs the owners don't complain. When you actually look under the hood, you often find a lot of bugs/features from questionable installs, partial hardware failures, etc.
  23. mrfjsf

    mrfjsf Member

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    The pipe facing downward should be connected to the high pressure relief on top the boiler. Your relief is "reliefing" the pressure if you have water coming from that pipe. Relief valves are set at 30 psi from the factory. This is telling me you have a good bit of air in your system. Normal is about 12-15 psi. Do have a pressure guage? It should be part of the aquastat on the side of the boiler. Do you have an expansion tank? Is it a bladder tank? This will be indicated by a shrader valve and also a tag that states what the air charge is. If it is a bladder expansion tank, depress the shrader, if water comes out, your bladder is shot and you need a new expansion tank. If it is not a bladder style tank and it is an overhead tank laying on its side with a drain valve at the bottom and a sight glass on the side, check your water level. It should be no more than half full of water when the boiler is running and up to temp. If it is full, drain it to half. If this does not solve your pressure issue, I can try to guide you through pushing the air out of the rest of your system.

    To address your zone heat issue. If they are using pumps for each zone instead of a central pump and zone valves, each zone must have a ball type check valve. Otherwise, there is absolutely nothing to stop water to flowing to that zone when the stat is not calling. It will siphon from the other pumps running. If you cant find a check valve for this zone, you need to have one installed, period. If you have one, it is likely stuck open.

    Here is a picture and description of the check valve you took a picture of below with the insulation on it. You should have one of these on every zone if you do not have zone valves.

    http://www.pexuniverse.com/store/product/34-swt-bronze-horizontal-flo-check

    EDIT: Are your pumps on the return side of the boiler?
  24. willworkforwood

    willworkforwood Feeling the Heat

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    As said earlier, this sounds like a bad aquastat or controller. A non-condensing boiler should never drop down to 70*, and the water from the pipe is an indication of high temp/pressure, and maybe even a boil-over. You need to get someone in to get it fixed ASAP, because this type of boiler can be damaged by abnormally low/high temp swings. And until the repair guy arrives, you can try to manually control the boiler via the t-stat, keeping the boiler temp gauge within the 120-180 range. It's unusual to see so many problems from new work that's only 7 years old. It might be a good idea to bring someone (new) in to evaluate the whole system - maybe there's some underlying reason for all of these problems.
  25. BARTSFAM

    BARTSFAM Member

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    UPDATE: Friday 01/27/2012

    Almost $600 later, I am all fixed!

    I am not very mechanically inclined, but I beleive this is what the heat man said. First, he said that I have a "cold start" system, and that if nothing is calling on it for heat, then the boiler is not going to kick on.

    I needed two air vents replaced. Both were corroded.. Also the backflow preventer valve needed to be replaced. It also looked corroded and covered with metals from my water.

    The man said that it was actually hot steam that was going to that zone, because the water pressure was zero, and the system was low on water.

    So for those three things, plus an annual cleaning, $568.15.

    Thanks to everyone for their advice.

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