Troubleshoot intermittent lock-out on gas boiler

Steve Garson_2

I woke up this morning to no heat. Looked at boiler and all zones were on, but no heat. This is a WM GV-4 boiler with Honeywell S9301A1001 controller.

Shut-off power and restarted.

Power LED - check
Purge LED - check
Igniter LED - check
Valve/Flame LED - on then off and process starts again. Though sometimes is stays on and things work fine.

Does this mean the gas valve needs replacing, or are there other tests that can be done? Is there a way to test the gas valve, besides confirming that it is getting voltage to open? Is it possible that the controller itself is the problem?
I'm guessing the boiler is 25 years old. Been living here five years.

EdTheHeaterMan

Are you sure you have a SG-4 boiler? I looked up the part number and the SG model number is not on the list

There is a sequence of operation that your boiler and control MUST follow. If one of the steps in the SOP fails to prove, then there will be no flame.

JUGHNE

Flame sensor is always the first suspect for this situation, IMO.

I believe you have a hot surface ignitor which does double duty as a sensors also.

Tough to clean as they are fragile. Maybe replacement time.

EdTheHeaterMan

That sequence of operation includes
1. Call for heat to the S9301A1001 control
2. Pre-purge: the blower operates and the circulator pump operates
3. the limit switch is closed and the blocked vent switch is closed
4. The HSI Hot Surface Igniter Glows bright orange
5. Gas valve opens
6. Main flame
7. Flame sensor senses the flame.
8. Burners until the call for heat is over, or the water temperature is reached or another limit device is triggered.

So it is possible that the gas valve is defective or the control board is defective. There are several other possibilities that are less expensive to rule out.

Dirty Flame Sensor*1. (check this one first)
Dirty tubing connecting the blocked vent switch to the vent*2
Blocked vent
Defective flame sensor
Defective HSI*3
Defective Limit Switch
Defective blocked vent switch
Defective Blower

hope this helps

neilc

while you're watching the LEDs,
are you seeing any ignitor glow?
any flame at all?
quick flame and out again?

Steve Garson_2

Thanks for the input everyone. The boiler is a GV-4, not an SG. The ignitor and blower are new. It seems that the flame ignites and then goes out.

dullknife1

dullknife1

Did u check the cone burner?  They blow out after awhile 

JUGHNE

I had one of these in my house for some years, the only change was the upgrade control board.
It may have had the same symptoms.
Same ignitor/flame sensor (combined function) for that time.

It sits in my basement as it was upgraded to a ModCon.
Make an offer to get the entire boiler/parts.....please!

dullknife1

Not Weil Mclain’s best moment. In the top 3 of their worst designs

dullknife1

The real problem I will reveal if Steve pulls the burner and it’s intact

Steve Garson_2

Cone burner is intact.  New igniter and blower this past winter.  It’s been working fine all day.  Tough troubleshooting an intermittent issue.

dullknife1

Thankfully you’re going into summer. Cut your boiler out take outside. Put your hose (water) in the exhaust and let it do its job.  Yes you have to flip it a few times but  after all regular checks Pan out you have to remove all the sludge from the bottom of the boiler. Might have to get a few tools in there unless you have really skinny hands and Arms.  If you want to be warm next year start looking for a better design. The sludge at the bottom gives you intermittent problems you will never see or understand until you replace one and pretty much accidentally see the problem 

dullknife1

Sorry 

Steve Garson_2

I really question the validity of what you are saying.

109A_5

Hello @Steve Garson_2,

Some troubleshooting info here. Although there seems to be at least 1 logical typo.
https://www.weil-mclain.com/sites/default/files/field-file/gv-series-4-manual_1.pdf

FYI due to the age, this is a possibility.
honeywell s9301a1001 integrated boiler control
https://youtu.be/MNtJiqOaOhg

dullknife1

Steve. I really hope I’m wrong. we replaced every part that could be replaced on that boiler and I mean everything. And that was back when I did not have a camera phone. It wasn’t until we cut it out and saw what oozed out of it and figured this was what was causing the intermittent problem. We did not clean it up of course we put in an 80%, so the customer would have consistent heat. Good luck maybe we did miss something 

Steve Garson_2

I'm thinking that the controller, being 30 years old, could be the issue. It's worked perfectly with the exception of yesterday's lockup.

dullknife1

dullknife1

I really didn’t want to put this out there, but I did want to let you know that it’s possible almost unbelievable, but possible. I can’t believe somebody with a camera actually put that on the Internet. You could be halfway there or hopefully not.

tim smith

We have had to take boiler out, split sections apart, having new gasket kits with us. Scrape and flush and reassemble. The pin heat x becomes very scaled after years and is virtually not cleanable with out dismantling. Real pain and very likely not cost effective but few clients wanted us to do anyway. Think I would say no now.
Tim

dullknife1

Sorry Steve, I thought this was an ongoing intermittent problem. 

JUGHNE

Sorry to come back late.

If you have an ignition/burner problem, it is, IMO, the flame sensor or pressure switch problems.

Do you show voltage across the air pressure switch when the blower is running?
No voltage indicates the switch is closed. It has to stay closed during operation, would open only when blower shut down.

FWIW, my GV-4 (series 2) from 1995 came with the UT-EC 1013-100, when it acted up with (IIRC) similar symptoms, the replacement was WM-GV 1013-200-448 (Gold Module Conversion Kit).