Honeywell T40

[slowdown ave]

When I call for heat, the wires become dead.?

 

[CountryFan]

What are you testing between? Sounds like it's a 2 wire stat? Photos of it?

 

[Harry Bloomfield]

When I call for heat, the wires become dead.?

If you are taking your measure, between the live and the switch-wire, then when you call for heat/turn the stat up, it will show no voltage difference between the two terminals.

 

[slowdown ave]

When I call for heat all wires go dead.
Before calling 1 red and 3 yellow give live reading

 

[slowdown ave]

This is a new replacement. In the hope it would fix the problem. Replaced like for like previous Stat 23yea
rs old

 

[CountryFan]

When I call for heat all wires go dead.
Before calling 1 red and 3 yellow give live reading

This is a new replacement. In the hope it would fix the problem. Replaced like for like previous Stat 23yea
rs old

Only 1 should be permanent live, yellow switched live should only have voltage when switched

 

[denso13]

When I call for heat all wires go dead.

How are you measuring this? If you are measuring between 1 and 3 then what you are getting is correct, it won't show any voltage when calling for heat.

 

[slowdown ave]

The indicator light is not coming on. When I call for heat. Where should I be looking for a fault

 

[Harry Bloomfield]

When I call for heat all wires go dead.
Before calling 1 red and 3 yellow give live reading

The only way to be sure what you are measuring, what's live and what's not, is to measure against a known reference. That basically means connecting one probe of your meter, to something definitely well earthed, the other probe on the terminals you have concerns about. Then report back.

The earth, might be the metal back box of the stat, or the earth pin of a nearby socket.

 

[slowdown ave]

I call for heat and the red goes dead

 

[Harry Bloomfield]

I call for heat and the red goes dead

Sorry, but that is telling us nothing useful.

Put one probe to earth, then with the other probe....

With stat on minimum report the voltage on blue, yellow, and red wires.

Repeat as above, with stat on maximum.

 

[slowdown ave]

It started as an intermittent fault. I've replaced sunvic 5601 actuator and the duo valve rj2802. 3 weeks back I replaced the fan ideal classic Ff360 at the moment I am turning the valve stem manually

 

[slowdown ave]

Red reads 133.2. V
Blue. 00. 368
Blue.. 00.372