Honeywell V8043 hard to activating when connected to Nest

Fab · June 4

I have a hydronic system with 2 circuits. 1 that activate the zone valve v8043 actuator and the other circuit is the endswitch that activate the boiler

My house used a 3 wire cord, but only used Red and White and Green was not used. I needed a common wire so I used the green wire and hooked it up to the 24V 40. V.A. that was used for the zone valve. I placed it on the terminal of the transformer side that goes to the Valve first. I also then moved it to the wirenut that connected the return from the thermostat.

My issues is when I call for heat the valve seems to struggle and barely moves and does not hit the button, when I place it at the nut it barely moves. When I place it at the terminal, it moves a little bit more but not far enough to touch the button.

I originally was using a separate 24 transformer adapter to power the nest but that was a temporary thing, and the valve had no issue, infact it moved a lot faster. My thoughts are that for some reason its not receiving enough ?power? to move and sorta conks out half way when its connected to the honewell valve adapter.

EdTheHeaterMan · June 4

When using only two wires to a thermostat you may connect the R on the thermostat to the zone valve and the W on the thermostat to the Transformer. This will work fine for many years because there are only the two wires.

This will not work when you introduce the Common wire. R on the transformer MUST be connected to R on the thermostat, W on the thermostat MUST be connected to the zone valve motor and The other zone valve motor wire MUST be connected to C on the transformer.

Aree you using the V8043E (Yellow wires) or the V8043F (Screw terminals TH TR)

Double check your wiring

Fab · June 5

I realize what I was doing. I was connecting the C wire that came from the thermostat into the line that goes into the valve, instead of the wire that "exits" the valve and goes to the transformer.

Now I'm not sure if I remembered wrong but because at least when I tried it this time. Connecting it at the terminal of the transformer does in fact work (I made sure that the wire was securely attached to the terminal), I'm not sure why I thought it didn't or maybe it didn't because it wasn't secured properly so the moment I lose connection the thermostat stop sending call for heat and I mis took that for it halting.

EdTheHeaterMan · June 5

Here is an example of what not to do. The 2 wire on the left will work, the three wire on the right will NOT work

This is how to properly connect the NEST. R on the Transformer to R on the NEST. W on the NEST to TH on the V8043. TR on the V8043 to C on the transformer. C on the NEST to C on the transformer.

This may require some rewiring of the rest of the zone valves. All zone valves should be wired R from Transformer to R on thermostat, W on thermostat to TH on V8043, TR on V8043 to C on transformer. If ALL the zone valves are not wired the same way, you can have a condition where the transformer may fail if two zones call for heat at the same time.

If you have the V8043E then TH and TR on the diagram are the two yellow wires on the zone valve

Fab · June 5

Here is a diagram that best represents my system.

I drew my mistake (illustrated by the X) and then I drew my correction (illustrated by the green check mark)

EdTheHeaterMan · June 5

OK. I see a problem. you have the C from the thermostat going to the same place as one of the R or W on the thermostat, That is where you have the Red X.

Just changing the C to the other side of the zone valve may or may not solve the problem. Here is an example of how it will not work.

In this picture, the R from the transformer goes to one of the yellow wires or to the TR on the zone valve. The Other yellow wire from the zone valve or the TH goes to the R on the NEST. The C from the NEST goes to the R on the transformer and the W from the NEST goes to the C on the transformer.

This is an example of how it will work:

In this picture you can clearly see that the R from the transformer goes to the R on the NEST. The W from the NEST goes to the Yellow wire or the TH on the zone valve. The other Yellow wire or the TR on the zone valve goes to the C on the transformer. And the C from the NEST also goes to the C on the transformer.

BUT….

Don't just change the wires on the one zone valve if you need to. All the Zone valves MUST be wired the same. To be clear, If you need to swap a wire from W to R on one zone to make it work, then you must change W to R on every other zone the same way. Otherwise you may let the factory installed smoke out of the transformer. That can get expensive and it doesn't smell very nice either.

You can always get one of these smoke keepers from the auto parts store. You want the 3 amp variety.