Heating Help

Issues with & Replacement of Honeywell L8148E Aquastat

We have a Honeywell L8148 that has started to act up and in
lieu of spending $450 to have a technician replace it, I’m interested in
swapping it out myself.
This will be the third time within 6 years of ownership that
the aquastat will have to be replaced.
To give some background of the problem, the burner will
sometimes fail to ignite. The “solution” to the problem is giving a slight
jiggle to the plug and wire shown in the red box of the attached image. The
burner ignites and heat is restored.
Then the same problem will happen again, usually at 3 in the
morning of if we’re away for the weekend only to return to a house with an
internal temperature in the 50s.

So, I assume it’s not possible to replace the suspect plug
or circuit board and a total replacement is in order. It seems like a
straightforward r&r, though I’m a bit uncertain about the physical
connection of the aquastat to the boiler (see attached image).
Do I need to drain the boiler prior to unscrewing this nut?
Do I unscrew the aquastat off this stem?

Any .02, thoughts and advice would be very welcome.
Regards,
PF

The plug you are

"jiggling" is the place that a vent damper if one were used could be plugged in. If you are going to have your contractor replace the relay then install a Universal Replacement L8148J, the plug will be eliminated and that is not a problem as you do not have a vent damper anyway.

Hmm...

Hi Tim,
Thanks for your thoughts. Interesting tidbit about the damper in that last year, the technician that installed this current aquastat unplugged the damper for some reason; if I recall correctly, he said it wasn't working and that we were just wasting energy by keeping it in the open position, so he must have placed that plug in place of the damper plug. Interesting in that the tech that visited 2 years prior said it was no problem to leave it open. (Which train of thought is the right one? I'm still trying to get up to speed on boilers, relays and dampers.)

Nevertheless, I plugged the damper back in and the boiler has now come back to life (it shut off again about half an hour ago, as you might notice in the pics, the temp had dropped down to 120.)
Do you think this is the cause for the recent failures of the boiler to remain on and hold temperature or does the aquastat need to be replaced?

damper danger

Try this: get the damper to actuate one more time by turning the power off and back on. With the blade in the OPEN position (the flat shaft will be vertical, look up inside the draft hood with a flashlight to verify) find the little switch on the side of the vent damper motor and place it in Man. Hold Open position. The unit should work with the damper open all the time. Your damper jumper plug is probably loose.

Damper

With the damper functional, you save about 2% on overall fuel consumption.

But, those dampers are fairly expensive, so for some the payback is not there.

Update

I removed the jumper plug and plugged the damper back in. The boiler has been performing perfectly ever since. Can't believe I had been dealing with the jiggling issue for nearly 3 months! Thank everyone for your help.

PF

Keep an eye..

It could be that the end switch in the damper has sporadic issues and will work sometimes and not another.
I have done 50/50 on removal or replacement, but was up to the customer.

Replace your own... if yours starts giving trouble again

http://www.beckettcorp.com/Product2/productdetail.asp?detailid=35

When my Honeywell failed, (intermittent Bad solder connection,) I replaced it myself with this Aquasmart, reasonably priced, easy to program, it works great, has an option for built in LWCO, was easy to install, has smart control for fuel savings, & I was able to wire up my existing SlantFin specific 4 wire plug Damper Harness.

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Tim