Reznor tube heater question

Larry_7

Been away from the Wall a while. Alot goin on here. Recently helped install Reznor radiant tube heater. had to order the fresh air kit to bring outdoor air to the burner. The kit included a "fresh air relay". It has a 120V coil wired in parallel with the inducer motor. The contacts are in series with the pressure switch. Stumped us what the thing can accomplish this way. Called the rep and it's to allow the pressure switch to reset in the event of a high wind condition but he was unable to explain how it does this. The unit works as before, just curious as to how and why this configuration. Anyone able to shed light on this please do. Another quandry...relay has 4 terminals. 2 for the lo-volt contacts and 2 for the 120V coil. An ohm check across the coil shows open but it works. Solid state or what?? Also literature is sadly lacking in reference to the relay. No mention of it in the troubleshooting section. Think the model is VR100xxxxxx...it's direct spark to burner.

Thanks,

Larry

Dave_22

Hmmm....

On the relay wired to the inducer motor, where does the contact go to ? It must signal something that " the motor is running and the pressure switch made". Sounds like some type of permissive signal. The relay is wierd. Does it have a coil you can see? I've always seen 120VAC relays with a low resistance. Low voltage relaysI've seen around 2-4K ohms. That's interesting......

Larry_7

re: relay

the relay is sealed I think. I looked about getting under the cover but didn't want to break it so left it alone. The thing is wired so that whenever the 120V inducer is powered, The 120V coil has power also. The contacts are in series with the pressure switch. It is wierd I agree...or so simple we're over thinking it. The way it's wired, whenever the inducer runs the NO relay contacts close allowing 24V to continue to the press switch and after proving the press switch 24V back to the DSI control to initiate the burner cycle. We can't see where this arrangement adds anything more to prove but it has to be there when using the fresh air kit. Hopefully someone familiar with it may see the post and jump in. About the coil, I checked in all the ranges available on my meter and shows open but it works...weird.

Thanks,

Larry