Author Topic: Fan Coil Advice.  (Read 2987 times)

Offline Sergroum

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Fan Coil Advice.
« on: November 16, 2014, 11:31:29 PM »
Greetings.

I wonder if anyone has encountered a similar problem before. I'm yet to visit the job to take any data and readings, but fan coils are something I've never touched before, so any thoughts would be welcome.

So, it's a 2 pipe fan coil system, currently set to heat. The problem is that the thermostat does not shut down the heat when it is satisfied. The blower shuts down if the thermostat is turned to off, but otherwise works at all times, regardless at what you set the temperature to.  My first reaction would be to check the thermostat, but evidently the client already purchased a brand new thermostat and changed it, with the new one acting exactly the same. He then installed the old thermostat onto a blower in another room and it worked perfectly there. So I'm guessing ... it's not the thermostat.

A valve? A relay somewhere at the blower? Does the problem sound familiar to anyone? These guys actually 'have' heat, so I wont be coming there tomorrow, but figured I'd run it past more experienced lot before I get there.

Offline Admin

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Re: Fan Coil Advice.
« Reply #1 on: November 17, 2014, 04:45:31 AM »
Quote
He then installed the old thermostat onto a blower in another room and it worked perfectly there. So I'm guessing ... it's not the thermostat.

There's a blower in more than one room, or is this one hydronic air handler that heats the whole house?

If it's a hydronic air handler I would make sure the circ pump is not being energized constantly by a faulty board.  There also would be a check valve that might be stuck open.  Most hydronic systems have a recirculation mode that might be causing the circ pump to run too often.

Offline harshal

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Re: Fan Coil Advice.
« Reply #2 on: November 17, 2014, 05:57:59 AM »
That's relay.I think they have that relay that keep sticking.if u working on air flow unit possible ly they have 2 relay in blower compartment .I will change them n see.

Offline Sergroum

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Re: Fan Coil Advice.
« Reply #3 on: November 17, 2014, 06:23:30 AM »
It's a condominium. They have two blowers in separate rooms with water pipes going through them. Twice a year, the management of the condominium changes the temperature of the water from heat to cool and vice versa. While the thermostats inside the condo control the individual blowers that circulate the air past those pipes and back into the living space. I'll be able to know more tomorrow, somehow I was lead to believe there is no control board there in principle. Everything is 120v.

Offline viking

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Re: Fan Coil Advice.
« Reply #4 on: November 17, 2014, 01:13:46 PM »
I would look for a wiring problem or as already suggested a stuck relay. Really cant be anything else.

Offline walker

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Re: Fan Coil Advice.
« Reply #5 on: November 18, 2014, 09:18:41 AM »
most likely a relay.  if the system was working fine before and no one has touched it, its far less likely to be a wiring problem.