OOOOLD Rooftop gaspac

[bonneyman]

Rather than hijack the melted thermocouple thread, I decided to start another related one.

Came across this unit a couple of years ago. From the mid to late 60's, but it had intermittent spark ignition! They did it with all sorts of old style electro-mechanical relays and pressure switches. It also uses a mechanical (which expands upon heating to close the flame proving circuit) switch - no digital at all!

The customer chose to replace it rather than attempt a fix. But, I figured you all (and especially the AC folks!) would get a kick out of this old dog.

 

[LS6 Tommy]

I remember similar machines. The owner got their money's worth out of it.

Tommy

 

[zmaxmotorsports]

Ive never seen anything like that around here,looks like a service guys nightmare to say the least.

 

[bonneyman]

Notice the two square relays in the center? The black and white ones? They are single throw, multiple pole switches that always caused problems. The units became known as the "B&W relay units".
The problem was these relays were not hermetically sealed. So, dirt and ants could get inside and gum up the works or burn the contacts. Luckily, I figured out how to disassemble the relay and clean out the crud. (Started using a matchbook striker pad to clean the contacts. Talk about old school!) Often that was all that was wrong with a non-functioning unit. Fairly soon I snagged a couple of spare B&W relays and just swapped them out, then took the used ones home and cleaned them. Then tossed them back into the rotation.

Fairly straightforward to service. You just had to know the sequence of operation and do hop-scotch troubleshooting. Alot of the newer techs got stumped by this unit. "What? No computer to plug in and tell me what's wrong?"