Taco zone valve failures

[Tempest]

I had a new hydronic heating system installed 2 1/2 years ago and have had 4 zone valve failures to date. The system has a NTI Trinity boiler and 3 zones using Taco 571-2 zone valves connected to a Taco 4 zone control module.

3 of these failures were the power head. The small plastic 'switch lifter' melted loose and allowed the heater to run continiously till it burnt out. The other was a cracked bellows on the valve stem allowing water to leak. I checked voltage to the valves at various times and it's been between 24.5 to 27 volts.

I'm wondering if others have had this trouble with these valves. Is this common, or could Taco have had a bad batch or parts? Or should I consider replacing these with a different valve. Any recomdendations for a reliable valve?

[stopro1]

maybe an A14 tip was used to solder the valves in without disassembling them first?

[casturbo]

Verify the wiring is correct. I believe the wiring schematic is available online or you can see it on the power heat itself (the new ones are gold colored and a have a wiring schematic sticker on them). Since terminal 2 is shared between the transformer and the heating control, it can easily be miswired and cause all sorts of issues.

Assuming the wiring is correct, verify the thermostat heat anticipator is set to maximum amperage or at least .90 amp. The Taco power head is a power hungry head, so be sure to give it the amperage it wants. The taco power head is very very reliable ASSUMING they are gold colored. Previously, the heads were green colored and no where as reliable as today's gold heads.

[shadetree29]

The company I work for has had sporadic problems with the taco zone valves. They have switched to the Honeywell Zone Valves and have run into a lot fewer problems.

[farupnorth]

We are installing the Honeywell Zone valves due to the Taco 500 series having failure issues too. I do like the Caleffi Zone Valve, but the distributor cannot keep it stocked here. Has any one used the new Taco EBVs yet?

[Maineah]

Are your Taco zone valves installed per instructions? if they are installed in any way other than horizontal they can have the kind of problems you are having-
As casturbo said the green ones were pretty much junk, gold colored works great!

[skippedover]

[QUOTE=Maineah;1739331]Are your Taco zone valves installed per instructions? if they are installed in any way other than horizontal they can have the kind of problems you are having-
As casturbo said the green ones were pretty much junk, gold colored works great![/QUOTE

Maineah is right on the money. Most installers think the proper location for the power head on a hoizontal pipe is in a vertical position, so the power head is on "top" of the pipe. This is incorrect as the heat from the water pipe is constantly acting on the powerhead. The proper way to install the 500 series is to put it on a vertical pipe so the power head gets convection airflow across the louvers in the power head for cooling purposes.

The EBV and EBS valves I've also had good luck with. These are the 4-wire valves, motorized ball valves. The original ones could be manually set to either the open or closed position. Upon a call from the thermostat, the valve would totate 90-degrees from the set position and on the completion of the call from the stat it would rotate another 90-degrees. This means that if set to the "Open" position manually, a call from the stat will close the valve and when the call is ended, it will open the valve again. Taco had so much trouble with techs who can't read and understand that they had to redesign the valve so it is open only on a call from the stat. I tell ya, if you can read, you can learn an awful lot. If you can't, well, what can I say? I guess Taco redesigned the valve for those who can't.

[Tempest]

These are the gold valves and installed in a vertical pipe run. Wiring is also correct. I opened one of the heads to get a better look at it. The plastic lifter is only melted at the point it attaches to the switch - the switch is just 2 metal reeds with contacts between them. I'm now thinking that the reeds get hot from the resistance of the contacts when they are moving between open and closed. The end switch in these units is a snap action switch - gotta wonder why they didn't use a snap action switch for the heater coil as well.
Maybe I'll consider having the Honeywell valves installed after this season.
Thanks for the help.