residio S8610U

Grallert

Hello
I have a laars mighty therm, actually two. One has a Honeywell S8600 control where the pilot remains lit during the call. The 8610 drops the pilot right after the burners fire up and then they go out and the whole cycle starts over. Ignition, pilot, burner flame, off restart. Is there a way to set the 9610 for constant pilot? or is that even the issue? For all I know this has been going on for a long time but I doubt it. What am I missing? Any help would be greatly appreciated.
Thanks folks
M

Steamhead

Might be a bad flame signal. You really need a pro to fix this. Where are you located?

109A_5

Hello @Grallert,
Looking at the manual, I would say your 8610U unit is defective or wired wrong. OR !!! it is working correctly and there is not enough Gas pressure and/or flow to keep the pilot working with the main burner active. I suppose it could be a gas valve assembly issue too depending on the system.
By your description I'm not sure if the system with the 8610U basically works OK for the whole call or it is continuously ignition cycling and you are not getting normal heat with that one unit.

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Honeywell-S8610U3009-Install-Instructions.pdf



Seems like the flame detection is probably working OK since the main burner fires.

dko

The S8610U is not an OEM unit and is a universal replacement. Could you take a photo of the S8610U wiring and also of the control on the other unit.

JohnNY

On the 8600, does the pilot ever go out? Or could the pilot valve be stuck open?

Grallert

So here are some pictures of what I have. Checking pressures I have about 5+ inwg to the upstream side of both valves (two boilers). The wonky boiler shows 1-2 inwg to the down stream side of the valve I forgot to take a picture but as the one picture shows the funtioning boil has about 4inwg the the burner.
The other valve is new out of the box from the supply house. I have to blame parts but I'm leaning that way.
The wiring is as directed. The 8610U is the replacement for the 8600.

Grallert

JohnNY said:

On the 8600, does the pilot ever go out? Or could the pilot valve be stuck open?

The pilot does drop
out just after the main burners ignite. Which made think control or wiring or a dip which. Didn't occur to me that gas pressure could be a culprit but I'm definitely not getting a good reading from that valve. (it's a new valve BTW)
This all started because there was some serious roll out on this boiler I found a number of the burner tubes were blown out, They're replaced now.

JUGHNE

Is that pilot clean and does it have enough pressure?

Or you could trade the spark/flame sensor from the good boiler and see if the problem stays with the boiler.

109A_5

Hello @Grallert,

Looks like you may have found the issue or an issue with the Gas pressure, maybe there is debris on the inlet of the gas valve assembly.

If necessary and if you have not done so I would verify the wires go to the appropriate gas valve's terminals and their connections. You never know what the folks before you did.

Also you could verify that there is 24 VAC still at the MV/PV to PV terminals when (the instant) the pilot erroneously goes out with the 8610U unit. The 24 VAC should go away when the 8610U unit determines the pilot is missing. Not sure what that delay time is (if any), maybe only a second or two.

Grallert

Good advice! Thank you I'll verify 24, but in the meantime I've got a new valve on standby.

Grallert

." I have" to blame parts " I just reread this. I meant to say I "hate" to blame parts!! Sometime new parts are bad but I hate to jump to that conclusion. I do have a new valve in the wings just in case. Good thing there are two if these boilers and one can carry the demand this time of year.

EBEBRATT-Ed

If it's natural gas shouldn't you have 3.5" wc downstream of the gas valve?

Grallert

The Boilers spec 4. the faulty boiler is only seeing 1to around 2 with no change after adjusting.