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Thread: Circulator pump running continually

  1. #1
    DIY Junior Member wildcatjones's Avatar
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    Unhappy Circulator pump running continually

    Recently converted in floor heating system in newly purchased house to hot water baseboard system; boiler is propane fired. When thermostat is turned up the circulator starts and is then followed by the boiler firing up. Maximum boiler temperature achieved is 115 degrees Fahrenheit, resulting in cold house. It appears that the circulator pump is running continually. I understand that for baseboard heating to be fully effective the boiler should be operating at a temperature range of 160 - 180 degrees Fahrenheit. Would the circulator pump running continuously be the reason for not achieving the proper temperature range? Any help with this would be much appreciated - Thank you.

  2. #2
    In the trades Dana's Avatar
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    The output of the baseboard varies with temp, but it still puts out quite a bit of heat even with 115F water, but clearly you need a higher temp if the room isn't being brought up to temp.

    The problem isn't the pump, it's either the boiler's settings, or a mixer valve that had been mixing down the boiler's output with return water from radiation. I assume you've purged the air in the system and it's getting a reasonable amount of flow, and that the 115F temp is measured at the boiler, not at the baseboard?

    If it's not a modulating/condensing boiler running it at 115F for extended periods will damage the heat exchangers, and may shorten it's life to less than one full heating season. What boiler name/model is it?

  3. #3
    DIY Junior Member Smithtb's Avatar
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    In most systems the circ will run anytime there is a call for heat. The question is, is the boiler shutting off at the max temp of 115f or not. If it is, its a limit or control setting. If not, its a mxing valve, circulation, or undersized boiler problem.

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    DIY Junior Member wildcatjones's Avatar
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    Thank you Dana and Smithtb, for the information - sorry for the delay in responding; had difficulty logging on (also using dial up internet connection, which is proving to be very painful). Had the contractor who installed the baseboard heating (2 zones, one long and the other shorter with thermostat located in the shorter zone) now back over on a couple of occasions - still not working properly. The boiler is 20 years old (manufactured by firm based in Burnaby, British Columbia - no longer in business) initially used for slab heating. This is what is now happening: Boiler cycle consists of water temperature (at boiler) initially at 160 F; then when thermostat is turned up (starting the circulator) the boiler temperature drops to 120 - 130 F and essentially remains at that temperature indefinitely. The boiler keeps firing almost continually like this with the temperature in the longer zone achieving only a maximum temperature of 62F, which is really not adequate. When the circulator does stop (which is only for a couple of minutes at a time) the boiler temperature does build up some, but as soon as the circulator starts again the boiler temperature once again settles to the 120 - 130 F range. Checked the limit control settings and they are at 160F MIN and 180F MAX. Not sure that the individuals being sent over by the contractor are thoroughly versed with the electronics of the system. Any additional comments would be much appreciated. Thank you.
    Last edited by wildcatjones; 11-24-2012 at 06:53 PM.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Did the boiler heat the house before you added the baseboards, or are the baseboards the result of adding to the house? It sounds like the boiler is not firing properly (poor burner performance) or internally, there's so many mineral deposits that the water going though is insulated so much, it can't transfer much heat. WHen sitting there not moving, it can get up to temp.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member wildcatjones's Avatar
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    Thanks Jim. The boiler was tied to the concrete slab (pipes within concrete) heating system for the last 20 years. Converted the entire house to baseboard system making use of the old boiler. Does look like the boiler is just simply not able to heat the water sufficiently. Guess the question is, "why". If it's mineral deposits causing the problem, can that be corrected?
    Last edited by wildcatjones; 11-23-2012 at 08:33 PM.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    A good tech will have a burner analyzer that will show how well the thing is tuned up. Also, you can watch the gas meter while it is on. One CUFT of natural gas has about 1000BTU. If your unit is 60% efficient, you should get 600BTU out of each cuft of natural gas used. Watch the gas meter with a timer and see how much it uses per unit of time, then you'll have an idea if it's producing what it should.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member wildcatjones's Avatar
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    Do not have a gas meter as this is a propane fired boiler. Am sure you are correct about the present efficiency of the boiler being totally inadequate, as I did notice that the propane tank is already showing 60% depletion and the winter heating season has barely begun. Will get after the contractor and press him to do a thorough analysis of the boiler and the electrical controls. Likely have not been forceful enough to date. Perhaps the boiler and controls should be replaced with a new high efficiency unit - will keep you posted. Thank you.
    Last edited by wildcatjones; 11-24-2012 at 06:56 PM.

  9. #9
    Master Hot Water Mpls,MN BadgerBoilerMN's Avatar
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    A clear demonstration of the difference in efficiency between a radiant floor slab and the crude convector misnamed, baseboard "radiation". How about we start with a proper heat load and finish with a new boiler sized to the load. Oh yes. Once we have the heat load we could measure the fin-tube to see if it will heat the house at a 180F AWT before we get too far ahead of ourselves...again.

  10. #10
    In the Trades Tom Sawyer's Avatar
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    Either

    The boiler is underfired or undersized
    There is more baseboard than the boiler is capable of supplying (see above)
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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