PDA

View Full Version : Hydronic circ pun won't stop running


finalcut
Feb 17, 2008, 08:39 AM
I have a Burnham boiler with three heating zones controlled by a Honeywell R8182H controller. Heat is going on in one of the zones even when the thermostat is set lower than the room temperature. The circulation pump is going non-stop. I would like to prevent the liquid gold in my tank from disappearing! Any help out there?

Eric D
Feb 17, 2008, 09:03 AM
FinalCut,

Is this a new problem or has the system always been this way? Has there been any changes in the system since the problem started? It could be a number of things that could be causing this, but one thing you could start with is the zone relay. Check to see if it has 24 volts going to it when the pump is running. If it doesn't, the relay is most likely stuck on. If it does, you need to trace back to find why it is being supplied 24 volts when heat isn't being called for.

Keep us posted on what you find.

Regards,

Eric D

finalcut
Feb 17, 2008, 10:33 AM
This is a new problem. The only change I've made is hitting the reset button on the two thermostats that I normally use.

Before testing I need to first identify the zone relay. Inside the Honeywell controller there is a circulator relay (is this it?) and burner motor and ignition relay. Could the circulator relay be stuck on? I don't have a voltmeter but if I can't troublesheet anything else I'll get one.

finalcut
Feb 17, 2008, 12:24 PM
More info if it helps...

I live in Maine. It's cold. Two of my three thermostats are turned down to 55F. The other one is shut off. The burner circulation pump is constantly running and feeding hot water to one of the zones bringing the room temperature of the two zones that are on to around62F. Both zones are at this temperature because my floor plan is somewhat open allowing heat to move freely around the first floor o the house.

The contact at the top of the circulator relay in the Honeywell controller stays up all the time. The burner hot water temperature stays within the high/low limit. The limit switches work fine.

Is there anything else I can check besides voltage that might help me isolate the problem? I can buy a relay for $75 at my local oil supplier. This Honeywell controller is only about 2 years old. Would the zone valve be sticking in the open position and if it was would this be forcing the circulator pump to stay on?

I can borrow a voltmeter from work tomorrow. Tonight I will probably just shut the boiler down for the night and light the wood stove.

finalcut
Feb 18, 2008, 02:08 PM
Here's today's update... I bought a voltmeter. My local oil supplier lent me a Taco power head to test on my zone valve for the zone that is not functioning properly. This oil supplier has been nothing but helpful short of coming to my house and to lend me this $85 part is pretty swell these days.

I tested voltage at the zone valve for three conditions: thermostat off, thermostat on set below room temperature, and thermostat set 11 degrees above room temperature. In the zone that functions properly I get a voltage reading at the valve of 24 when calling for heat but 0 for all other modes. In the zone that I'm having problems with I get 24 volts regardless of the thermostat setting. I get 24 volts even when the thermostat is off.

Even though it didn't make sense to me I tried replacing the power head of the zone valve. No change. Changed it back. I also tried taking a thermostat from upstairs (from my third zone that I never use) and swap it with the one in the zone I'm having trouble with. No change.

The circulation pump keeps running and hopt water keeps flowing to the zone that I don't ask it to flow to.

Any help out there?

Eric D
Feb 18, 2008, 04:25 PM
FinalCut,

Can you trace the wires back from the zone valve? They should end up at a relay. If you find it, this relay will have the contact end that one of the wires to the zone valve is connected. At the other end of the relay there should be the energizing connections that come from the thermostat or control board. The relay is used because the control board or the thermostat can't handle the current draw of the zone valve solenoid. You can check the relay once you find it by using the voltmeter to see if there is voltage on the energizing connections of the relay. If there is, disconnect one of the energizing leads and see of the zone valve turns off. If it doesn't, then most likely the relay is stuck in the on position and should be replaced. Hope this isn't too confusing. It is hard to explain writing it out then to show someone, but not much of an option from the web.

Eric D

finalcut
Feb 18, 2008, 05:14 PM
I can trace the wires from the Honeywell controller to the zone valves and from the zone valves to the TRANSFORMER. I don't have relays for each zone. I have one circulation pump with a transformer and three Taco zone valves.

I disconnected the wire that connects the zone valve to the transformer and the circulation pump now behaves as it should when I play around with the t-stat on another zone that I know does work. The circulation pump doesn't stay on now but only goes on when I call for heat on one of the zones that works properly.

What next? Could the valve portion of the Taco zone valve (not the power head) be stuck open?

Eric D
Feb 18, 2008, 08:24 PM
Could the valve portion of the Taco zone valve (not the power head) be stuck open?
What model Taco valve is it? I don't believe it would be stuck. If you discounted the power to it and the other zones are working as they should, it seems to me the valve must be closing when you discounted it. The real question to ask, why is the valve getting power when you are not calling for heat.

Eric D

finalcut
Feb 19, 2008, 05:28 PM
It's a Taco valve 572-2. The other two Taco valves I have are 571-2's. It's not stuck open because if I disconnect the t-stat wiring from it then the zone no longer gets hot water which means the valve is closed.

I'm thinking it's the wiring from the t-stat to the Taco valve since when I test there is no voltage at these wires. I've been wanting to relocate this t-stat to a more sensible location so I will run new wires. If it was bad wires to this t-stat would heat still go to this zone?

finalcut
Feb 20, 2008, 05:31 PM
One wire (red) from the t-stat goes to the zone valve and the other wire (white) goes to the transformer. I nget voltage at the zone valve but not at the t-stat.

Anyway, I moved the t-stat to a new location and ran new wiring from the zone valve and transformer to the t-stat and the problem appears to have gone away! Perhaps a mouse chewed through the wire?

Eric D
Feb 21, 2008, 08:18 AM
Thoughs pesty mice can be a real pain, along with red squirals around here. Glad to hear you got it corrected.

Regards,

Eric D

Native4life
Oct 7, 2009, 09:38 AM
FinalCut,

Can you trace the wires back from the zone valve? They should end up at a relay. If you find it, this relay will have the contact end that one of the wires to the zone valve is connected. At the other end of the relay there should be the energizing connections that come from the the thermostat or control board. The relay is used because the control board or the thermostat can't handle the current draw of the zone valve solenoid. You can check the relay once you find it by using the voltmeter to see if there is voltage on the energizing connections of the relay. If there is, disconnect one of the energizing leads and see of the zone valve turns off. If it doesn't, then most likely the relay is stuck in the on position and should be replaced. Hope this isn't too confusing. It is hard to explain writing it out then to show someone, but not much of an option from the web.

Eric D

Hi I seem to be having the same sort of problem. I know this post is over a year old but I hope your still around to help. I have disconnected one of the wires from the zone relay that go to the Tstat and the pump stops running. What next?