Fan G circuit not energized when heating

[stusviews]

You need to measure the voltage from the wires connected to the thermostat, not the control board.

[adv]

You mean that you want the measurements taken at the wires as they come out of the thermostat or at the unit but before they go into the control board? While W, Y, and G are connected to the control board or disconnected? The connection to the board is all 5 wires in 1 plug-in connector, not spades nor screws. So it is not easy to disconnect individual wires W, Y, and G and leave R and C connected. What I did before was leave it all plugged in and measure from the back of the connector.

I may be able to pull individual contacts out of the connector and measure W, Y, and G voltages while not plugged into the control board (but R and C are), is that what you want? From the previous I think that I know that I would find the following:
-When heating and Fan Auto: W = 23-24 VAC, Y = 0, G = 0
-When heating and Fan Always On: W = 23-24 VAC, Y = 0, G = 23-24 VAC
-When cooling, either setting: W = 0, Y = 23-24 VAC, G = 23-24 VAC
Is that all that you need or are there other measurements that I should make?

[stusviews]

Yes, that's the way to test the voltages, with only R and C connected you should get about 24VAC between G and C when calling for heating or cooling and the fan on auto.

[adv]

I was able to pull the W, Y, and G contacts out and leave just the R and C connected. I tested and it was pretty much the same:
-Not calling for heat: W = Y = G = 17.1 VAC
-Calling for heat: W = 24.8 VAC, Y = 17.4 VAC, G = 17.0 VAC

So this thermostat is screwed, blued, and tattooed, right? The "switches" that control W, Y, and G are all "leaking" and G seems to be sometimes inoperative.

[adv]

I just installed my 2nd Insteon thermostat and it works the same way. When the circuits are supposed to be off they read ~17 VAC. Could I have 2 thermostats that are bad or is this the way it is supposed to work?

[adv]

Did I lose you, Stu?

[stusviews]

Nope. I have no further recommendations.

[adv]

Does it appear to you that these 2 thermostats are defective?

You wrote earlier that "All three of my 2441TH thermostats energize G (~24VAC) whether calling for heat or for cool, otherwise the voltage is 0 (zero)." Can you absolutely confirm that is true?

[stusviews]

It'll take a day or two.

[adv]

OK, thanks.

[stusviews]

Checked and verified.

[adv]

OK, that's really strange. And it is a 2441TH Wired Thermostat (NOT for heat pumps), right?

I was on the phone today twice with Insteon support. The second time I was on with the support "boss", Dominic. He told me that absolutely the G circuit was NOT supposed to energize when calling for heat. But, then again, he also said it wasn't supposed to energize when calling for cooling either and I have verified that it does.

Another interesting thing is that he measured the VAC in the W, Y, and G circuits of the test thermostat that he had at the lab while NOT calling for heat nor cooling and he was getting residual voltage too. His was about 16 VAC. He was surprised. So given that he did not know that and his mistake about the G circuit being energized when calling for cooling I am not going to put much weight on the info I got from the support line.

So it appears that the thermostat does not turn circuits ON and OFF but rather HIGH (~24 VAC) and LOW (~16-18 VAC) to signal for heat/cooling/fan or not. Both of the thermostats that I have here and the one in the lab did that so I would think it is unlikely that it all 3 are defective in exactly the same way. When a solid state switch goes it doesn't usually act like that, at least in my experience. Also, I get residual voltage of about the same on the contacts of my furnace so I am thinking this is an industry standard, or one of them, maybe. Any HVAC techs out there that could verify this is, in fact, the way some (all?) heating/cooling control systems signal?

Stu: Based on your testing I am going to get yet a 3rd 2441TH and hope that it energizes the G circuit when it calls for heating. Yay.

[stusviews]

I tested with every wire disconnected from my HVAC except for 24VAC. Depending on your system, which seems to have unusual wiring, the result may be different with your HVAC connected.

[adv]

You tested with just 1 wire connected to the HVAC or 2?

[stusviews]

There's no power if only one wire is connected