Boiler/Taco Head problem

pitman9

Turn down all the t-stats.

Is there voltage between wire 1 and 2 on the ZV? If so, disconnect wire 1 from the 2nd zone. Wait a couple minutes. Does the ZV close? Should be no power at C1/C2 if it has. If the ZV closed you have a short in the t-stat wire to this zone. We see a couple of these every year. IMO, this is the most likely problem...unless the ZV is indexed open and someone forgot to close it. Don't ask me how I know about that one.

I wouldn't say it's impossible but I've never seen a Taco ZV fail open. That leads me to believe it's energized all the time.

bob_57

Boiler/Taco Head problem

Can anyone help? I own a split-level house built in the early '60s. It has 3 levels. It is heated by natural gas/boiler/baseboard w/3 zones. The boiler (Weil McLain) was installed at the end of 1997. We've had no problems except a taco head or two going out since then. However, since turning the boiler on this fall, the main floor (2nd zone) is continuously heating, even with the thermostat turned as low as it will go. The other two floors (zones) are fine. We have replaced the thermostat on that floor and we replaced the taco head for that zone. The only way to control the heating is turn the boiler off by the main switch or circuit breaker. The boiler is running continuously. We had a service tech come over yesterday and take a look (this tech works for the same company that installed the boiler back in '97.) He did an overall check of the boiler, taco heads and thermostats. He had us replace the taco head again (for the main floor-2nd zone). After speaking to him today and letting him know we have no change with the heating, he was going to speak to his boss about the problem. Well, I've now spent $$$ for 2 taco heads, 1 thermostat and a service call and still, the problem is not fixed. The boiler continues to run, 2nd floor is too warm and I would like to spend my money on what's really wrong. Can anyone help???

Rich P.

overheating

Is the zone pump running all the time? Put your ear up real close to hear it..
Does the Taco zone valve lever move easy all the time. With the power off?
Some times a bad valve ( the part soldered to the pipe could be stuck open, any corrosion?
Good Luck

Rich P.

Joe Mattiello

Diagnosing through elimination

Good Morning
I’m sorry to hear of all the problems your experiencing with your boiler. With the cost of gas these days, I’m sure you want to resolve this constant running of your boiler issue ASAP. Perhaps I can help. The Taco zonevalve has an end switch that emulates the thermostat, so when the thermostat closes, the end switch closes after approximately 1 ½ minutes. As long as the end switch remains closed the boiler will continue to run. Take the wires off the TT terminals on the boiler, and see if the boiler shuts off. If it does, then put the wires back on, go to the zonevalve and take the wires off terminals 2, and 3 see if the boiler shuts off. If it does, then methodically put the wires on terminals 2, and 3 until you uncover which valve endswitch is sticking. At that point if you still have not uncovered the root of the problem, continue diagnosing the problem through the elimination process up to the thermostats. Please advise, if you require additional assistance.


Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

Dick Charland

Possible shorted wires

If the zone valve is staying open allowing heat to flow and end switch pulling in the circulator relay with the thermostat turned down or removed completely, the TT wires may have shorted somehow causing the unit to be activated constantly. If the circulator is not running, head not opening etc. you may have something under the valve seat causing a gravity flow of heat.

STEVE PAUL_3

UNWANTED HEAT

The problem could be a valve stuck in the open position. Changing heads will not make any difference. If the the valve is open it will activate the end switch. The test is to remove the wire from terminal 1. If the boiler continues to run, the end switch is closed. Remove the wires from 2 and 3, if the boiler shuts the complete valve has to be replaced.

David_5

?????

If the valve is stuck open, and the head is not the cause, then how can the end switch still be closed with no call for heat?

David

Joe Mattiello

Taco valves if fail, fail closed

Normal failure mode for Taco zonevalves is closed. However, if the actuator is bad the endswitch can be closed.

Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

Empire_2

OK....

Since everything has been thrown at this puppy and still the same problem I would check as the taco rep stated to disconnect the stat wires from zone #2. If the valve closes and the boiler shuts down, I would check for any shorts from the t-stat to the zone valve. This should be an easy fix. Have you done any construction in the house latley? Nailed something? Also one last thing,...Why are heads being changed out when the problem cannot be identified? That's like replacing the carberator when the window squirts dont work... Amazing.....

jrc2905

I have had this problem before, look to see if the t-stat wires from the zone valve are rubbing between any piping or wall causing them to sort out.