Weil mclain ultra 105 gas valve fault after new valve

brokenheatguy

Last year I was getting gas valve faults and it would shut down my heater until I manually reset.   It started doing it once or twice after a few months it was happening weekly.   I bought a replacement valve and installed it.   It's been fine for this whole winter so far and in the past day it has locked out on me twice.  When I just did the last manual reset like an hour ago I checked the fault list and it said.  4 failure to ignites, 1 gas valve fault and 124 controller failures I believe it said.   I just wanna make sure I'm not chasing my tail with this before I replace the gas valve again.   Could something else be going wrong causing it to look like the gas valve is bad?  When it was bad the first time I could smell gas in my house when the boiler ran so I was pretty damn sure that was the issue then.   Oh and for other info I serviced it when I did the valve I replaced the ignitor, and flue temp sensor.   It was installed on 2012 and was fairly gummed up when I cleaned it....I only cleaned the burner side not the water side.   Any help would be greatly appreciated. 

HVACNUT

What Series?

brokenheatguy

It's a weil mclain s series ultra 105

HVACNUT

brokenheatguy said:

It's a weil mclain s series ultra 105

The tag on the inside will say the model Ultra 105 and under that, Series...? 1, 2, or 3. I don't think you've got the 4.

Also, natural or LP gas?

Big Ed_4

Did you set up the gas valve to proper O2 ?

brokenheatguy

It's natural gas I'll have to go look at the series but I believe it said 3.  I installed the gas valve just how the instructions said.  It didn't say anything about adjustment it just said if it's LP change the adapter.   It's run just fine since October of this past year.   

Big Ed_4

Cross contamination , gas pressure and improper combustion adjustments . Can flame out the boiler ..

Igniters and flame sensors , you already replace . I replace them every five years ..

You already replaced the gas valve , how does the wire harness look . You will need to set up the new gas valve for the sweet spot of combustion for your unit ..



Call in a tech which should have the equipment , he can call tech support ...800.526.6636 to help him

brokenheatguy

The harness looks ok..... no damage or crispy..... when you say have the tech set the sweet spot are you talking about adjusting the CO2 levels to the chart? By turning the gas flow screw?

109A_5

Hello @brokenheatguy,

"124 controller failures" does not sound good. I'd recheck that.

brokenheatguy

Does it reset failure count if you shut off power?  I don't believe I've reset them in a long time but I did shut off the power when I was changing the gas valve.   And yes @109A_5 that's kinda what I was inquiring about originally..... I was wondering if those controller failures could cause it to seem like a bad gas valve again... the first time it went bad the valve was locking it out daily and when it did run you could smell gas around the unit.   Since I put the new valve in it fired right up on the first try and hasn't given me any issues til now.   But I did find a video and the chart about adjusting the CO2 levels like Big Ed_4 had said. So I'll get that done I just need a tech with the tool

GGross

What are the actual fault codes that are locking out the unit? do you have the manual that will tell you what they mean? Most ignition faults have several possible causes, gas valves are actually a pretty uncommon failure on most units, the most common misdiagnosed part in my opinion

brokenheatguy

@GGross the actual fault code that is locking the unit is gas valve fault 1.  I just happened to notice the other codes when resetting it.   And yes I have the manual.  

GGross

The manual I have for that boiler shows 3 steps for when "GAS VALVE FAULT" appears, none of the steps are to replace the gas valve, does your manual show a different fault? these are changed sometimes between different series

"Check wire harness connections between gas valve and U-Control."
"Check resistance between "
"If lockout reoccurs replace U-Control."

brokenheatguy

yeah originally when it gave us the fault the first time I called a tech and had them come look at it.
He was the one that told me to replace the ignitor & flue sensor. He also tested the gas valve and said he thought it was intermittently sticking and told me i should get a new one so i replaced all that he said to.

brokenheatguy

I had quite a hard time finding a local tech that was familiar with these boilers. I got one guy that said he works on them all the time but he was backed up and could only talk me through getting it running over the phone. The guy that actually came over and tested it wasn't familiar with the unit but seemed like he knew what he was doing anyways.

brokenheatguy

I just read through my manual again and the series 3 says when a gas valve fault occurs its because the hardware controlling the valve didn't open or close within the allotted time frame. But it doesn't say anything about testing or replacing it.

HVACNUT

brokenheatguy said:

I just read through my manual again and the series 3 says when a gas valve fault occurs its because the hardware controlling the valve didn't open or close within the allotted time frame. But it doesn't say anything about testing or replacing it.

It will say when it's in pre purge, and when there should be ignition. An electric meter will tell you if there's 24 volts to the gas valve, and a manometer will tell you if the gas valve is actually opening with 24 volts.
The U-Control is probably out of warranty if that's the culprit. It's best left to a pro because it needs to be programmed for the 105. Firing rates, temperature setpoints, Priority designations, etc. must all be reset.
A combustion test and throttle screw adjustments if needed can be done at that time as well.
And don't let anyone drill a hole in the exhaust pipe. Remove the Flue Temp Sensor for the combustion test.

brokenheatguy

Ok im pretty capable when it comes to mechanical repairs. I have a multimeter, and I have access to a manometer and CO2 meter. If i took pictures of all the setup screens specs. I think I could change the Control unit on my own. Is there anything else that needs to be done when replacing the control unit. I wish there was an actual service manual that outlined steps for errors.

brokenheatguy

Ok I was just searching online just to see the cost of the U control module and I found a different manual from the one I have for my unit. I think this is the manual that @GGross was talking about. I'm going to wait until the unit craps out again and then I'll start diagnosing. I see online a lot of places say the u control unit is discontinued.

Mustangman

I mentioned this issue before on here. I live in PA. Over the last 2 years, we have had power surge issues and under voltage. the tough problem as it never fails when you are onsite. I have a few different data loggers. You program it for the hours you want to monitor, hook it up to line voltage, hot side parralel. All you are doing is sampling power,as frequently as you preset it for. You are not adding to the load. I have one that measures temp, humidity also. That quiets some problem customers when you can show them the graph.
Good luck
Steve