Taco ZVC 404 EXP. Erie Zone Valve open with no call for heat

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Old 01-18-13, 07:09 AM
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Angry Taco ZVC 404 EXP. Erie Zone Valve open with no call for heat

I have a Taco ZVC404 Exp relay box. I have two Erie vt2313 4 wire zone valves. One zone is overheating. The yellow light for the zone is off, but the red light for the zone valve is on. I tried disconnecting the t-stat wires to that zone, and the red light stays on. I guess that eliminates the t-stat. Valve is open, circulator running. Turn off power to relay and i can hear zone valve close. So its not stuck open. Turn power back on - everything works fine.... for awhile. Then i notice overheating. Also whoever wired this has the two red wires from the zone valve and the two wires from the 3 and 4 terminals on the relay all wired together with one wire nut. I tried seperating them and using two wire nuts, one for each wire coming from the zone valve. Now red light wont come on and circulator wont start. Also lots of clicking going on in the relay. So i returned the wiring how it was, but i have never seen one wired like that. So bad zone valve or bad relay?
 
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Old 01-19-13, 06:48 PM
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Offhand I would say 'stuck relay' in the ZVC... those are socketed, aren't they? Try swapping a pair and see if the problem follows the relay.

OR, wire it to a different 'channel', sounds like you have two unused on your panel.

But then I read further...

whoever wired this has the two red wires from the zone valve and the two wires from the 3 and 4 terminals on the relay all wired together with one wire nut. I tried seperating them and using two wire nuts, one for each wire coming from the zone valve. Now red light wont come on and circulator wont start. Also lots of clicking going on in the relay
I think that was wired like that because that zone valve has a bad endswitch. By shorting 3 and 4, you are bypassing the endswitch. When that zone calls for heat, the system will start up without waiting for the valve to open. Which is an 'OK' way to 'get by' for a while... but not permanently.

So bad zone valve or bad relay?
BOTH? maybe... endswitch has been bad for a while perhaps, relay recently crapped out? maybe?

Do you have a 'history' with this system? or recently became it's guardian?
 
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Old 01-22-13, 04:01 AM
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Thanks for the response. Yes, i did just inherit this system about 6 weeks ago. There was one zone not being used (zone 4 is going to the water heater) so i swapped the t-stat wires over to the empty slot and did the same with the 4-wires going to the suspect zone valve. I also ran a new set of wires to the zone valve thinking that there may be a short of some kind. Boom. So far the problem seems to be corrected. No more overheating and i have watched as the zone valve opens and closes appropriately. I do have a new actuator for this zone valve but was hoping to return it. Your post makes me second guess this. The cover was off of this valve when i inherited the system, which usually worries me a bit. Maybe i will hold on to it for awhile and continue to monitor the supect zone valve. Thanks again for the info. Just a plumber who really doesnt have a great understanding of electricity.
 
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Old 01-22-13, 03:20 PM
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Good, sounds like situation is under control!

C'mon back if you need anything else...
 
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Old 02-20-13, 11:41 AM
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Exact same problem with Taco ZVC403

Hi NJ,

I have the exact same problem with Taco ZVC 403. I inherited the system 3 years back, there was no problem until last month. I have 3 zone system controlled by ZVC 403. One of the zone is getting turned on without call. If I remove the wire from the controller for the particular zone, everything goes back to normal for day or two or for a week.

My problem is exactly same as explained by cmhebes.

I read your comment about stuck relay in ZVC. How can I test that? Is there a way fix it without replacing the controller.
 
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Old 02-20-13, 03:05 PM
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Does your panel look like this one?


image courtesy johnstonesupply.com

If so, you don't have relays... well, you do have ONE, but that won't cause the trouble you are seeing.

I think I was thinking about the SR panels when I responded to the original poster...

If I remove the wire from the controller for the particular zone, everything goes back to normal for day or two or for a week.
Which wire? do you mean cable? Explain exactly what you do to 'fix it' for a time...

My problem is exactly same as explained by cmhebes.
This would be:

NO YELLOW LEDs are lit.

At least ONE of the RED LEDs are lit.

Boiler keeps firing and heating that particular zone.

Correct?
 
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Old 11-11-13, 06:24 AM
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Sorry I lost track last year, now winter is back and problem is back.

NJ, you are the correct, I have exact model the one you have in picture.

on top, there are three Zone valve terminals. each has two wires. One wire is coming from each thermostat, and second is common. I am having issue with Zone 3.

When everything is working normal, thermostat calls, first Yellow light for T STAT gets on and then Red light gets on for the valve. Heat runs fine.

Then sometimes heat does not gets tuned off even the thermostat call has been closed. The thermostat reads higher temp then the set temp but heat continuously runs and no call for heat.

At this time, both red and yellow lights are on.

Wire Disconnection: I have been disconnecting the thermostat wire from the Zone 3. As soon as I disconnect the wire, both lights are turned off and valve closed.

Then I monitor the room temp, connect the wire to run the heat when temp gets lower.

When reconnected, if heat gets turned off automatically after the set temp then the leave the wire connected. If it does not, I disconnect the wire again.

Some time I have to do this process for 2-3 days before everything goes back to normal. After that ZONE works fine for few days, then back to same story.
 
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Old 11-11-13, 07:29 AM
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What you are describing sounds to me as if there may be an issue with the THERMOSTAT and not the panel itself.

If the YELLOW LED remains ON after the thermostat seems to be 'satisfied', it means that the signal from the thermostat is still present at the ZVC panel input.

Try swapping the thermostat from one zone to another and see if the problem follows the thermostat to a different zone.
 
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Old 11-13-13, 09:32 AM
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Thermostat test

Thank you for a quick response. I switched the Zone 2 and Zone 3 thermostats. I did not change the panel wiring.

Problem persists with the Zone 3. The replaced thermostat for Zone 2 works fine. Next I will switch the Zone 2 & Zone 3 wires at the panel to test the Zone 3 thermostat wire.

Wire test: Zone 3 was running. Yellow and Red light was on and the thermostat does not say heat on.

I switched the Zone 2 and Zone 3 thermostat wire at the panel. The Zone 2 got turned on, thermostat still the same.

Would you think I have bad wire for Zone 3?

One thing I did not change in the thermostat test is the back panel. I just changed programmable module.
 
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Old 11-13-13, 12:31 PM
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Would you think I have bad wire for Zone 3?

One thing I did not change in the thermostat test is the back panel. I just changed programmable module.
It sounds like a valid assumption that the problem is in the wiring.

You swapped thermostats, problem stayed.

Moved wires from 3 to 2 at panel, problem moved.

Yes, look at the wiring behind the baseplate... might have some wires barely touching.
 
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Old 11-23-13, 07:34 AM
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Wire Test

Finally I am done with wire test. I ran temporary wire and relocated the thermostat. Everything runs normal for a week. Thank you. You saved me from replacing the control panel.

Thanks again
 
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Old 11-23-13, 09:51 AM
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Great! thanks for the follow up! Good Luck!
 
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