Relay on a boiler

[bud--]

My guess is that the symptoms are not caused just by a relay.

"It"?

[tmurpha1hi]

Can I buy just the relay component or do I have to replace the whole honeywell box on my boiler? Sometimes when the heat wants to go on it keeps switching on and off very quickly just as the burners start to light.

[Existential Angst]

Well, if you can ascertain that this problem is caused by a specific relay on the board, then you *might* be able to add a relay. Basically, afaict, there are a few variables:

1. the signal going to the relay coil
2. the coil of the board relay
3. the switching contacts of the relay.
4. loose connection on the board itself.

Sometimes the contacts start to go, and you can remedy the situation by having these contacts control your external relay, which is a much lower current. I have, I believe, a combination of 3 and 4, where I added a new relay off the board relay, and had to physically shim the pc board to force mechanical/electrical contact of whatever had broken/cracked. goodgawd....

If it's (2), then you will have to do soldering on the board itself, to attach the coil of your external relay. If it's (1), then you have another problem, which may or may not be the control unit -- it could be a sensor, loose connection, etc.

I can't imagine thumbnail-sized relays on a pc board being able to handle

10+ amp blowers. Thus, it's not a bad idea to add a decent external relay from the gitgo, altho this can get cumbersome if the blower is multispeed. I just use two speeds, high for the A/C, and low for heat, and physically just switch the wires at season change.

The problem with stuff like this is that if you ever do require outside service, and an alt.hvac-type beer-swilling tech looks at yer artwork, he will likely exact a horrible revenge, price-wise.

[Tony]

These things must be junk. About 7 years ago I also had one go bad just when the warranty was up on a brand new boiler installation. Tap on the box and it ran, so I thought simply enough I'd open it up and either clean the contacts or resolder the bad connection. No luck at all. I too ended up wedging something on the board to make it work.

If you decide to buy a new one, I'd look for other brands. Honeywell has a problem!

[Existential Angst]

I believe these are hairline cracks in the brittle plastic base. Wedge it one way, you close the break. Wedge it the other way, you could open it further.

A dilemma would exist if there were soldered/printed circuitry on *both* sides of the board/break -- then, bending would *never* solve the problem! You would have to be able to place the edges of the board under pure compression. What a pita....

But for these companies, it's just mo' money and mo' money....

This happened to me on a Bryant furnase... don't know who makes their board.

It is maddening, tho.

[ransley]

Is the box a just a relay and transformer, mine is, but if its more than that how do you know its the relay. I have several Honywell relays maybe 50 yrs old working now, I have no idea how old really, Honywell relays just work. If its just a relay start by checking the voltage of it, there is a certain voltage and call a supply house or honywell to see if its in spec, or google. Switching on and off sounds like some saftey is cutting it out, check for loose connections, safteys controll the whole boiler, gas valve, maybe flue damper, low water etc. Once my pilot assembly got wet from a leaking pipe, a bit of water never dried on some external wiring and kept it from firing. I would make sure all connections to the main board are clean and tight first, the Honywell relay sould outlast the boiler.

[RBM]

You need to find out what's causing the relay to chatter. It is very unlikely that it is a faulty relay. When you say "Honeywell box", it gives very little usable information, as Honeywell makes dozens of boiler controls, some are just switching relays, but others are aquastat relays, which have more components in them that could cause a relay chatter. Sometimes boiler relay chatter is caused by a combination of very low amperage , typically ice cube type relay, used in combination with a current robbing charging circuit on the thermostat