Questions on Taco zone valves

Ken C.

If you have a hot water boiler with one circulator and multiple zones with Taco zone valves, and one zone only fails to heat, how often can the problem be cured by replacing the zone valve power head, as opposed to soldering in an entire new valve? Is it 80 percent of the time? 90? 50? I had this problem on a call yesterday, there was 24 volts across terminals 1 and 3, but the zone wasn't working. I switched the power head, but still no luck. I told the customer I'd have to replace the whole valve, but he decided to postpone the job. Is it common for the zone valve bodies to stick in the closed position? What causes that (mineral deposits)?

Tom M.

The 24V should go to terminals 1 and 2 to open the valve.

Terminals 2 and 3 are the end switch. Hope this helps.

Tom M.

Tom M.

The 24V should go to terminals 1 and 2 to open the valve.

Terminals 2 and 3 are the end switch. Hope this helps.

Tom M.

Joe Mattiello

Zone valves

Thank you, for using Taco products. Replacing, the actuator works most of the time, but occasionally it's the valve seat assembly that fails. Taco offers replacement valve seat assemblies, for all zonevalves. Additionally, these valve seat components are warranted for 5 years. For your convenience I attached a Troubleshooting guide. Please advise, if your require additional assistance.



Joe Mattiello
Technical Services
(401)942-8000 ext.484
Fax (401) 942-2360
joemat@taco-hvac.com

Ken C.

Joe, thanks for the guide. Two questions: Rarely is the voltage a perfect 24V, but what is the minimum and maximum voltage range for a Taco zone valve? Also, it mentions checking transformer output. I've heard of a "V A" rating, but can you elaborate on this and explain how to test it with a multimeter?

Ken C.

Tom, I hear the term "end switch" all the time, but I don't know what that means. Can you define what an end switch is?

Unknown

End Switch is

a switch which makes after a device has fully opened. It insures safety in many cases of a system firing when there is a closed device. It is built into many different controls, zone valves, vent dampers etc. In some devices by ANSI standard there may be two end switches (in case one sticks).

Unknown

Voltage \"24 volts\"

NEMA (National Electrical Manufacturers Assoc.) rated class II transformers under standard DC20-92 require out put voltages from 20 volts up to 27 volts depending on the amount of capacity of the transformer from "0"% demand to 200%. The ability of a transformer to handle three Taco Zone valves is built around that standard as a 40 VA (watts)transformer can at 200% capacity handle three valves.

To check the output of a tranformer it should be done under load and no load conditions.

With a load: in other words with the system energized and calling.

No load: disconnect wires from transformer.

You do this by placing your multimeter across the two transformer secondary wires (on some they are labeleed "R" and "C") your voltage reading should be pretty much the same with a load and with no load. If you under a load condition get a low reading and the no load reading is normal then the transformer is okay, your problem is in the load device, gas valve, zone valve etc.