Weil-McLain GV-4 Ver. 2 wiring:

icesailor

I have a customer with a W-M GV-4 Ver.2 LP Gas Boiler with Taco 572 zone valves, 2 heating zones and one for an indirect. It was installed about 10 years ago or more. I didn't install it. It runs three air handlers. It had wiring "issues" of unknown consequences. There is a gas service person who works on it. But, whenever the boiler goes off on safety, they call me first. I haven't futzed with the gas part, only the heating.

This unit is one of those that goes off "occasionally". Once every day, once every few days or once a week. No pattern. So, I had at it.

It has a Taco ZV 404 zone valve controller. For reasons of my own and to satisfy curiosity, I put my Mitco Amp-Mate in series in the thermostat wires from the controller to the boiler. The Amp Mate would run the boiler. When the boiler started on pre-purge etc, there was no amperage, just 26 volts. Once the burner fired, the amperage reading went to .05 amps. Once when cycling the burner, it didn't start and the amperage went to 1.0 amps. I changed the control and it never went out on safety and whenever the gas valve was open and the burner was running, the amperage was .05 amps. My question is, is it normal to have this amount of amperage in the thermostat lead? I asked around and no one had the foggiest idea about it.

So, I'm asking here. Any thoughts?

icesailor

Reflection:

On further overnight reflection, it seems that the amperage I see on the TT connections to the boiler are the control amperage. The old control had listed on the top, control amperage's with different valves or something. The highest was .06 Amps to .04 Amps. But there was no measurable amperage on the circuit when the burner wasn't running or calling. If the 572's didn't go through the ZC404 controller, there would have been amperage on the TT circuit or at the thermostat. But that would have .09 to 1.0 amps.

Is there something about this connection I'm missing? I'm just trying to understand this whole circuitry. Many electricians are clueless when it comes to control wiring in HVAC systems.

I'm not an electrician.

hot_rod

A good boiler

I had one in my home for many years. Being in a less than ideal location in the laundry room it would get coated in dryer dust. Usually cleaning all the connections with a spray cleaner and re-torquing the ground connections everywhere took care of the ocassional lockouts.



There were some upgrades to the control, search around this site for older post regarding GVs. The factory support was always very good when I had questions.



hr