Boiler relay help

Jamie Hall

You can replace that with any two wire thermostat — but before you do, make sure that it's the thermostat, not the wires. Disconnect the old one, and the boiler or furnace should shut off.

EBEBRATT-Ed

Yes R & W terminal on relay as already posted above

HVACNUT

Are you sure that's connected?

karter

Ok im.bench testing the r19a relay after I found the wire was bad and changed it out for a r89 relay. Power to line in 120v operation thermostat w r b screws jump w&r no response jump w &b relay pulls in have 20v on w&b. W&r. 2 volts. Is relay ok .

Jamie Hall

Bench testing? If you apply 24 volts to the relay coil terminals, the relay should pull in. The resistance across the closed contacts should be negligible (probably unmeasurably low). End of story on the relay.

Now. Let us create a circuit with a transformer. One output wire — call it hot — is connected through your thermostat wiring to the R terminal of the thermostat. The W terminal of the thermostat is connected back to one terminal of the relay coil. The other terminal of the relay coil is connected back to the other output of the transformer (we'll call it cold). Now if the thermostat is calling for heat, the relay should pull in and close. Where this gets a little odd is that the voltages may be slightly different depending on whether you have an electronic thermostat or a mechanical or mercury one. If it's electronic, you may see a voltage — probably half a volt, maybe up to a volt and a half — between the transformer hot and the W wire on the relay terminal. This is not a problem; it is in the nature of the electronics. Otherwise the transformer hot and the W wire should be at the same voltage. So long as the relay pulls in, it's good, the wires are good, and the thermostat is good.

I regret to say that I'm really not at all sure what your description describes in terms of testing here…

109A_5

" jump w &b relay pulls in have 20v on w&b. "

If W & B is jumpered how do you have 20 Volts on W & B ?

When the relay is energized do both sets of contacts have good continuity ?

I would put a 120 VAC load on the No.2 contact output to test. You could connect 'W' to 'R' and see if the relay latches on when the jumper from W to B is removed, and the 120 VAC load becomes active and stays active.

karter

Will hook up a pump and see if it works on bench. Also I have 2 b&g 100 ser. Pumps love them can see if they are running easy.i have 1 b&g mini pump how do I tell if its running