Please help! Water pump never stops!


  #1  
Old 11-01-05, 12:22 PM
zhang_xn
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Please help! Water pump never stops!

Hi Guys,

I noticed my water pump is continuously working regardless the setting from the thermostat unless I shut off the main electric switch. It was fine last winter. I need your kind help to find out what would the possible problems be.

My system is a gas hot water baseboard heating with a fairly old boiler. It is divided into 2 zones for both upstairs and downstairs. Each zone has its own thermostat and a valve to control the room temperature. Every time when the temperature setting is reached, I can see the valve has been shut off. So, there is no more hot water goes to the room.

However, even both zones are not heating, the pump is still running. I can see both valves have another wire connecting to a switch relay (RA832A, T poles), and the X poles of the relay are connected to the boiler somewhere I don't understand.

My question here is:
The relay is supposed to control the power of the pump, right? If the signals from the thermostats don't need to heat the room, it should shut down the relay and the pump.
I tried to disconnect both T and X poles of the relay, the pump is still running regardless the low voltage control input. Does it mean the relay is defected?

This is my first to be here, and any suggestions/replies are high appreciated.

David
 
  #2  
Old 11-01-05, 05:20 PM
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Ra832a

Here is what I've read about the RA832A: Low voltage control of two line voltage loads having a common power source. Are you telling me you have two low voltage sources?
 
  #3  
Old 11-01-05, 05:37 PM
zhang_xn
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Thanks Grady.

No, I only have one low voltage control which is connected to the valve. Since I have 2 zones, which need 2 thermostats for both upstair and downstair. Each thermostat connects to its valve. So, I have 2 valves. In addition, 2 valves connect together and goes to my relay low voltage control pole (T, right?).

So, basically, I thought as long as one thermostat outputs the heating "command", the low voltage control should receive that and start the pump and the valve.

Now, the problem is that the pump never stops even I totally disconnected the low voltage control of the relay. Why did that happen? Is the relay working in that way, or that is a defect relay?

Thanks. David
 
  #4  
Old 11-02-05, 06:29 PM
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David

OK, clearer now. It sounds like the relay is stuck (contacts welded?). Here is how to check: Turn off power & disconnect the line voltage out put wires from the relay. Turn power back on & check for voltage across the terminals from which you just removed the wires. If you have 120 volts, there is a real good chance the rely is stuck for one reason or another.
 
  #5  
Old 11-03-05, 11:55 AM
zhang_xn
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I fixed it.

Grady,

Thanks for your help. I opened the relay and cleaned up the contact. It seems working now. When the thermostat control comes, the relay acts and the pump runs. Everything is back to normal now.

I heard that for the pump, ideally, it should run continuously. Does it really hurt the pump if I use thermostat to control it on and off? But it saves some gas cost, for sure.

Thanks.

David
 
  #6  
Old 11-03-05, 04:10 PM
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Circulator problem

I doubt your repair will last very long. The contacts in those relays are only silver plated. I suggest you replace the realy or at least get a spare soon.
It will hurt nothing to run the circulator only on a call for heat. In fact, that is the way most gas fired boilers operate.
 
  #7  
Old 11-03-05, 04:17 PM
zhang_xn
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Yes, the relay looks pretty old, and I believe I would have to replace it anyways later on. It just costs too much to get a relay for more than CAN $150. That is why I am trying to use it as long as possible.

In the meanwhile, I will search around to see if there is any other relays can replace this RA832A, and cost less. RA832A can switch 2 line voltages, but in my system, I only use one.

David
 
  #8  
Old 11-03-05, 04:26 PM
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Ra832a

Will work just fine. You likely could use an RA89A. Another option is to use a fan center such as a Honeywell R8285A for about 1/2 the price. Just mount it on a 4x4 box.
 
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Old 11-03-05, 04:41 PM
zhang_xn
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Thanks Grady

I will take a look of those 2 relays, and might replace my old one.

Thanks.
 
  #10  
Old 11-03-05, 04:48 PM
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Relays

If you opt for the fan center, you will want to hook your low voltage wires to terminals R & G. Connect the load (circulator) to the "normally open" wire. Be sure to put a wire nut on the "normally closed" wire.
 
  #11  
Old 11-03-05, 05:23 PM
zhang_xn
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Ra832a

Hi Grady,

Thanks for your information.

I am still not quite sure how RA832A works. The thermostat control is connected to T poles of 832A. That is the low voltage (mine is AC 27V) control signal, right? I have another pair of wires connecting the X poles of the relay and the boiler. I believe that is for the control of the boiler. Is that right?

So, when the thermostat control comes to the T pole, it controls the relay to provide voltage for the circulator, and also, it closes the X poles to provide 27V for the boiler control. Is it right?

The thing confuses me is that when I disconnected the thermostat signal from the T pole, T pole has 24 V voltage. I believe that comes from the internal transformer of the relay. Is it correct, or not?

Thanks.
 
  #12  
Old 11-03-05, 05:31 PM
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Sounds right

I was not able to get a schematic for the RA832A so I don't know for sure. You don't have another transformer in the system do you? Maybe in the boiler's aquastat?
 
 

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