Why is a hot water baseboard always hot?


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Old 03-19-16, 01:54 PM
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Why is a hot water baseboard always hot?

I am puzzled.

We have a gas boiler and hot water system in our large building which has 3 zones (3 B&G 100 pumps).

1 zone (pump) controls the upstairs. Funny thing, the front rooms are where the thermostat is. The baseboards in the front are always on. The temperature rises to above 75 degrees. The back rooms are cold. The temperature on the thermostat is set to 62 degrees. I don't understand why the baseboards are hot, and the temperature is above 62 degrees when the thermostat is properly set and appears to be working properly. The only way to get heat in the back rooms is by setting the thermostat well above 75 degrees.

If I shut off the main electric switch that controls the pump for that zone, it has no effect. Seems like the switch isn't controlling the flow of the water through the baseboards. If I shut off the valve on the pipe, which controls the flow of the water that the pump is connected to, the pipes get cold.

What is causing the water to run through the system even though the motor on the pump is not running?

I hope this makes sense as I described it, but it makes no sense to me why this may be happening.

Thanks, for whatever you may be able to offer.
 
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Old 03-19-16, 02:34 PM
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Does your System have a Flow-Chek Valve (or equivalent) which, if stuck open, may be allowing some convection of hot boiler water, even when the Boiler is supposed to be idle, and the Circulator Pump IS NOT running ?

I had one which was heating part of the house even during the Summer.
 
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Old 03-19-16, 03:14 PM
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Wow. OK. That makes sense. Is there any way to check if it is stuck open? How could you tell other than having it replaced?
 
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Old 03-19-16, 05:04 PM
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We'll let some heating professionals chime in here first; but you can check for such a device on the primary feed pipe leaving your Boiler near the top on it's way to the Living Quarters; probably before the Air Scoop. My activities which are frowned on, included gently smacking it a couple times with a rubber mallet.

See if you have one first; the name and function is probably right in the casting's Boiler Plate.

There could be many other causes of your problem . . . . the symptoms just reminded me of one of mine. Convection is pretty powerful, and though slow, used to be a method for distributing heat. I once had a 2nd floor apartment 45 years ago, and we complained about the Oil Fired Gravity Hot Air Heating System (when oil was 18.9˘ a gallon) and my 1st LandLady then promptly installed a FHA Fan in the ducting and caused 75 years worth of dust and soot to migrate into our living quarters and screw up all the wallpaper and our clothing. Point is that somehow, gravity alone (convection) had heated that 2nd floor for 75 years or more. I suspect the 1st Floor LandLord also got some benefit out of our heat too.

Your hands will tell you whether heated water is rising past that area for no good reason (other than convection).
 
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Old 03-19-16, 07:23 PM
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CounterPoint How Hydronic System Components Really Work [pdf]

TECHNICAL BROCHURE FHD-501A
[page 18, pdf] The Flo-Control Valve
[page 20, pdf] “Weightless” flow control
[page 21-23, pdf] A hydronic brain teaser
So why is the radiator getting hot? It’s because Zone #2’s Flo-Control valve has dirt under its seat. Watch. . . . How do you solve the problem? Just unscrew the top of the Flo-Control valve and clean it out. Easy!
 
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Old 03-21-16, 09:13 AM
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Well probably the answer is clear to you knowledgeable folks, but I don’t understand how turning the thermostat up can compensate for a stuck open flow control valve. Probably staring me in the face.

The only way to get heat in the back rooms is by setting the thermostat well above 75 degrees.
 
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Old 03-21-16, 10:15 PM
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Read [page 21-23, pdf] A hydronic brain teaser.
Next move the system pumps from the supply to the return, now the first radiator of zone #2 is hot, and if that is where the thermostat is located then the zone rarely calls for heat.
 
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Old 03-22-16, 08:38 AM
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OK HeatWorm, I got it. Thanks. I misread post #1 and thought there were two zones, one with the thermostat set to 62 and one with the thermostat set to 75. My bad.
 
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Old 03-23-16, 05:55 PM
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Just cover up the radiators or louvers when you don't need heat.

If there comes an unusually cool summer day and the heating system is still active, then you could uncover the radiators.
 
 

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