Oil Boiler fires intermittently

[Clint]

So here's the situation. I have a Weil-McLain oil fired boiler with an older Beckett burner (by older I mean that the boiler is probably original to the house, 1940 ish, and the burner slightly newer). Recently I have noticed that the burner will fire for a second or two, and then shut off, only to repeat the process a few minutes later. This happens regardless of thermostat setting. The thing is, it doesn't always happen. Sometimes the system will work like a champ for days.

Last night I finally got worried enough that the temp in the house was going to continue to drop, so I called a service company. The guy I got on the phone told me to check the Cad Eye Sensor to make sure it was clean. Turns out I don't have one...I have an older stack switch. The service guy that came out today spent about 15 seconds in front of the boiler, pronounced that my stack switch was bad, charged me $99 bucks and left.

So, does it sound like my stack switch is bad? What does that mean, (repeated questions to the service tech only got me half-assed answers).

Any and all opinions are welcomed.

BTW, I know that I should just replace the boiler, but the 3k to do it hasn't arrived yet...

[Charles Schuler]

When is the last time you had that thing serviced?

Oil-fired burners require annual maintainance. The electrodes burn away, for one thing.

[Speedy Jim]

Well, the "stack switch, aka Protect-o-relay" includes all the line voltage controls/connections for the burner motor and ignition.

If the burner motor AND ignition completely stop during the intermittent off period, it *could* be due to a poor contact on the relay or even at the terminal board.

If the intermittent continues, leave the cover off and see if the relay(s) drop out.

And don't rule out some intermittent condition in the branch circuit feeding the burner.

Get some more clues before throwing any money at it.

Jim

[RBM]

There are any number of possibilities, some having nothing to do with the burner or stack relay. Depending upon what controls are on the boiler, and how they're wired, it could be a bad switching relay for a circulator or high limit aquastat, possibly even the thermostat

[mm]

How do you know that? Why do you say you know that? The way out of problems is not always to have lots of money and spend lots of money.

One should only spend what needs to be spent, and he shouldn't be embarrassed to fix something instead of replacing it.

You're half way there, since you're asking how to fix it, but you still seem in the back of your mind to think you should just replace the boiler.

(And replacing things often comes with its own problems.)