Relay switch on control board unreliable

[cs2kplus]

Ok. I posted recently as "unknown problem". Now I know. The relay switch on aquastat controller is unreliable. Picture included shows it as grey cover with spring hinge that says honey well. If you tap it then boiler will kick on. My question is, can this be fixed as opposed to replacing entire board? The entire assembly comes inside a metal housing. I read you can spray wd40 on it. So far it's running. But it seems like it needs a jump start ...press with finger...now and again.

 

[cs2kplus]

I sprayed with electrical cleaner. Followed by wd40. Currently it has stopped sticking. I have seen a video where a guy cleans the terminals with sand paper.

 

[Sponsor]

 

[Dana]

WD40 isn't your best friend here- it's mostly naptha solvent that can soften/dissolve and compromise many plastics. I haven't tested it on the thin lacquer insulation on transformer & relay windings, but wouldn't be surprised if the lacquer were soluble in WD40 too.

Cleaning the contacts with hard abrasives can work, but stick with the finest grits, and blast out the fine grit/dust with contact cleaner or compressed air.

Is there a part number (stamped or printed) on the metal housing for the whole assembly?

 

[Jadnashua]

The lever sticking versus a poor connection in the contacts are two different things. With the power off, you should be able to press the contacts and release, and it should freely move between the two positions. Sometimes, all it takes if the contacts are slightly dirty is to slide a strip of paper between them, push them closed and pull the paper out. If you can solder electronics, you might be able to find an exact replacement for that relay. If there's room, you might also be able to cobble up an external one.

Note, one reason why a relay could be intermittent is if the input voltage to the coil is out of spec. It won't always pull in if the coil voltage isn't within specs. Once it does, there may be enough magnetic field to hold it in. That could be a driver to the coil, a corroded connection, and other things, so a new relay may not do anything. So, in that case, it may require a new board, or finding the proper driver chip/device. Few of these things come with a schematic or mark the parts, so troubleshooting is often, is the board good, or bad. If bad, replace, not repair.

I did have an older boiler that I cobbled fixes for that kept it running for a few years before I decided to replace it with something more efficient and reliable.

 

[cs2kplus]

Jad....


Your saying all the right things.

So far the simple spray wash seems to be working. I know....till my luck runs out.I was going to physically clean contacts, but I will not go there just yet.

I did think about re-soldering a new relay. I'm just not smart enough to know what I can replace it with. To me the external one sounds like a good way out. Once again...not sure what to get. My thinking is "any 24 volt"? Perhaps I can get my father in-law into the task. He does that stuff. He's very cheap too. LOL.

I can get a new board. That is about $300. Boiler folks want to charge $650 installed. What a mark up! Or can try myself. Does not look all that tough. But once again. I am a mechanical, not electrical person.

Yes - I am absolutely cobbling here. We have said year after year we are going to get new. We are now feeling that day approaching.

I suppose I am hoping to GET THROUGH this winter. Hardest part about doing this stuff is doing it while it's dang cold and fear of screwing it up and freezing. Although I have quite a supply of electric heaters on deck.

Thanks so much for your response, It was very helpful!

Wayne

 

[cs2kplus]

WD40 isn't your best friend here- it's mostly naptha solvent that can soften/dissolve and compromise many plastics. I haven't tested it on the thin lacquer insulation on transformer & relay windings, but wouldn't be surprised if the lacquer were soluble in WD40 too.

Cleaning the contacts with hard abrasives can work, but stick with the finest grits, and blast out the fine grit/dust with contact cleaner or compressed air.

Is there a part number (stamped or printed) on the metal housing for the whole assembly?

WD40 isn't your best friend here- it's mostly naptha solvent that can soften/dissolve and compromise many plastics. I haven't tested it on the thin lacquer insulation on transformer & relay windings, but wouldn't be surprised if the lacquer were soluble in WD40 too.

Cleaning the contacts with hard abrasives can work, but stick with the finest grits, and blast out the fine grit/dust with contact cleaner or compressed air.

Is there a part number (stamped or printed) on the metal housing for the whole assembly?

 

[cs2kplus]

Yeah. I was a bit leery about wd40. I uploaded part number of entire box.

 

[Dana]

The L8148E aquastat is still being manufactured, can be had for under $225 at web stores if you can't find it locally. (It costs $50 more than that at the orange box store, which may or may not have it in stock.) Spend another $10-15 for the appropriate heat conductive compound to guarantee good thermal conductivity between the sensor bulb and the sensor well on the boiler if swapping it out DIY.

Anything look familiar, aside from the green FR4 materail printed circuit board vs. whatever that antique you have is using?

 

[cs2kplus]

Yep. I see I can get a replacement. Am I smart enough to install it? Questionable. My father in law would be. I'm not all that great with a meter and knowing what I am measuring.

Ha - yeah antique. Actually the new one does not look all that high tech.

So, it is currently functioning after cleaning. Now I start with the backup plans. One includes replacing the entire boiler, which is overdue.

Thanks Dana

 

[Dana]

Yep. I see I can get a replacement. Am I smart enough to install it? Questionable. My father in law would be. I'm not all that great with a meter and knowing what I am measuring.

Ha - yeah antique. Actually the new one does not look all that high tech.

That's right- it's the pinnacle of 1940s boiler controls, now using slightly better circuit board materials. The old aquastat controls have fairly high reliablity (yours is probably old enough to collect social security, or at least carry an AARP card. ) But they're not very sophisticated, and do not optimize for efficiency or comfort.

Many newer cast iron boilers come fitted with programmable heat purging controls.

So, it is currently functioning after cleaning. Now I start with the backup plans. One includes replacing the entire boiler, which is overdue.

Thanks Dana

When considering replacements, to NOT just replace like-for like, or you'll end up with another ridiculously oversized boiler that will never meet it's AFUE numbers. Since you have a heating history on this place, start with a fuel-use based heat load calculation, using wintertime-only gas bills. (In winter there will be less error from solar gains & other gas appliances.)

If a modulating condensing boiler is a possibility, run this math on the zone radiation, zone by zone.

Do all this well BEFORE soliciting proposals from contractors. Most don't have the time or interest in doing it fully by the book. Some simply refuse to do any arithmetic whatsoever, specifying boilers with more output than the radiation can even emit, which forces it to cycle, putting extra wear & tear on the boiler while eating away at efficiency.

Most old cast iron boilers I encounter are 3x+ oversized for the space heating load, and many are 2x oversized even for the radiation they're hooked up to. ASHRAE recommends holding the line a 1.4x the heat load at the 99% outside design temperature (which is big enough to cover Polar Vortex disturbance cold snaps) but for small to medium sized homes that have been upgraded with air sealing, insulation, better windows, etc it's often hard to find an appropriately sized cast-iron boiler solution- they're all too big(!). But there are reasonable modulating condensing boiler solutions for almost any house.