Electric Heat Relay Troubleshooting

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Dansos

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PA
I don’t do too much work with older heating systems and need some help troubleshooting an electric baseboard problem. The client has 2 Honeywell electric heat Relays connected to main panel that are tied in with 2 240V Double Pole 20Amp circuits. Voltage off breakers checks out (120V per line) and I am getting 120V off all three wires (Red Blue Black) for the Relay. At that point I thought it was a bad thermostat (Honeywell round Mercury mechanical stat) so I disconnected the stat and jumped the 2 wires to see if heat would come on. Am I WRONG in assuming that by directly connected the 2 24V stat wires the heat should kick on?
 
Better yet, do you have 24 V at the contactor coil? If so but contactor not pulling in - probably a bad contactor coil. If not, then you have problem somewhere in control circuit, which is most likely only a transformer, thermostat and contactor coil(s).
 
I bet he is using one of those heater relays with a self contained low voltage source.
it could be DOA.

If both lines are hot -240v and the relay does not close then the module is bad.

If the relay closes and you get 240v out then you have a heater issue.
 
Don't think it is a common thing for this kind of system but is possible the relay is a thermally actuated type - 24 volts powers a small heater instead of a contactor coil, and that heats a bimetal strip that operates power contact(s). Such setup will have an "on delay" as the bimetal is being warmed, as well as an "off delay" after 24 volts is lost and bimetal is being cooled.
 
kwired nailed it this was done to be much quieter than a contactor.
 
Thanks for the responses guys. I totally blanked out on the 24v to the stat reading. I was not getting anything so I changed the relays and it’s working fine.
 
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