Alpine 150 failing to sustain flame after ignition

Boilershepherd

The boiler proceeds through direct ignition. The flame exists for not more than one second. Then goes to post purge.
Ive jumpered the high limit in test.
The Rectifier and gas valve have been replaced.
It has operated through one single DHW heating cycle.
Gas pressure o.k.
New flame sensor...
All discussed with tech support.
Any suggestions

hot_rod

got sis it grounded properly?

Boilershepherd

It was grounded properly. And there had been a factory issued update to solve an EMF problem during ignition with certain date codes. I think that's how it read.
Awaiting adjudication on warranty replacement.

109A_5

Hello @Boilershepherd,

Boilershepherd said:

The boiler proceeds through direct ignition. The flame exists for not more than one second. Then goes to post purge.

Then what happens ? Another attempt ? Lockout ? Any Fault codes ?

Boilershepherd

It will cycle for hours never logging a fault code.
The sum of combustion on each cycle is just a flash and a whoof.

109A_5

Hello @Boilershepherd,

With troubleshooting, the things I would be initially interested in, is the system 24 VAC being maintained during the short time the gas valve is being energized.

What in the highlighted path is causing the gas valve to de-energize. Not sure if you can test any of this.

109A_5

Hello @Boilershepherd,

Maybe my first question should have been, basically in general does it act the same regardless of a DHW call or a Thermostat call ?

HomerJSmith

Might clean the ignition and sense probes and make sure it has a good ground. You might have to check each device in the 24V safety circuit that 109A-5 showed.

Boilershepherd

Thank you both.

Yes the voltage at the board was monitored. It was a steady signal.
The behavior was similar to either a call for DHW or SH.

The sensor and ignition assembly were well maintained. It received a full service.
the entire burner assembly was cleaned.

The unit never logged a fault. It was as if the call was dropped at the moment of ignition. It would trial for ignition for days if left alone.

pedmec

Did you get ignition after you changed the gas valve? The gas valves are not always set up for operation when you receive them. You most likely have to increase the downstream to get gas into the burner. This a the basic setup for a negative pressure gas valve.

As long as you have proper inlet gas pressure and a combustion analyzer you can fix this. But it shouldn't be done without a combustion analyzer. You will never be able to set it up properly and can cause carbon monoxide poisoning. Safety first

109A_5

Hello @Boilershepherd,
What is the Rectifier ? I don't see a Rectifier device. I assume you meant Transformer. Also all the Vent/Combustion Air Piping has been inspected for obstructions ? Also was the gas pressure verified at the instant of flame ignition ?

Assuming something is removing power from the gas valve just after ignition you have to find what is doing that to gain troubleshooting direction. For starters I would measure the voltage between J5-1 and J5-2, what does it do at the moment of the gas valve closing ? This would determine if the controller is shutting the valve down or the string of safety sensors and cutouts to the left on the ladder diagram is.

If the voltage between J5-1 and J5-2 goes up to 24 VAC at the instant the gas valve closes the controller is interrupting the power to the gas valve. If so is it the controller (bad internal solder connection, corrupt software) or another sensor (not on the string of sensors) like the flue temperature being goofy.

Also you should have 24 VAC between J5-1 and J8-2 all the time.

Boilershepherd

Hello 109A-5,

What is a rectifier? In this case, it's what tech support has been calling the gas valve cable harness. This negative pressure gas valve is DC volts. It is the plug at the end of the harness that rectifies the AC voltage.

All of the above suggested monitor of the test points have been performed for hours at time.
No faults logged, no error codes, no hard or soft lockouts.
Gas pressure watched for hours. no venting obstructions.

All safety switches bypassed singularly and simultaneously.
Yes, the throttle screw on the GV has been opened.

Absolutely zero change in performance. Always initiates combustion for a split second, goes off.

Boilershepherd

Adjusting the throttle screw on the GV didn't cause a change in performance.

Inhibiting the air intake partially did not make a change either.

I ramped up the Lightoff Fan speed by 16% from 3000RPM to 3500RPM.
It lit on the first attempt and all subsequent attempts.
The DHW cycle completed and changed over to CH with a low delta T alert.
Auto reset alarm and the unit fired on all attempts.
Combustion analyzed, high and low fire. All parameters acceptable.

Thoughts?

109A_5

Hello @Boilershepherd,

Boilershepherd said:

What is a rectifier? In this case, it's what tech support has been calling the gas valve cable harness. This negative pressure gas valve is DC volts. It is the plug at the end of the harness that rectifies the AC voltage.

I find nothing in the online manuals I am looking at that supports this claim that it is a DC Gas Valve and pictures of Gas Valve's label online show 24 VAC. No hidden Rectifier or Diode in the harness. All information I can find on the Gas Valve is that it is 24 VAC unit. I could not find the word "Rectifier" in the manual. If you have the wrong Gas Valve it may not work correctly.

Assuming the correct Gas Valve is presently installed in the boiler you need to determine what part of the electrical system is shutting off the Gas Valve immediately after it is energized to provide troubleshooting direction.

All safety switches bypassed singularly and simultaneously.

So the voltage between J5-1 and J5-2 goes up to 24 VAC at the instant the gas valve closes ? Then it appears the Boiler Controller is interrupting the power to the Gas Valve. If so is there something the Boiler Controller is monitoring incorrect ?

Is this your Boiler ? Alpine ALP150

https://s3-us-west-2.amazonaws.com/catsy.782/Alpine+IO+Manual.pdf
http://bostonheatingsupply.com/Burnham/Burnham Alpine I&O Manual.pdf

108882-01 Gas Valve
102975-02 Gas Valve

Big Ed_4

It acting like a bad limit

JUGHNE

The only reference to "rectifier" that comes to mind is flame rectification flame sensing.

Used by most ignition modules to monitor presence of flame.

If the flame sensor is not in the fire or if there is not a good ground path thru the the pilot light hood/burner then the system would go to lock out and probably retrie.

That ground path needed may not be a wire but rely upon the piping/burner hardware etc.
Sometimes adding a ground wire from the electrical chassis ground to the hardware might work.

Also.....WAG.....is it possible that the spark and sensor connections are reversed?
Either at the board or burner point.

The flame sensor would maybe work as an ignitor, but the ignitor would probably not work as flame sensor.

Boilershepherd

I saw that 24V ac in the manual too. It's incorrect. Speak to tech support 1-888-432-8887. The rectification components are in the plug that attaches to the GV. It wont appear in the manual.
If you have an opportunity to work with the Sage 2 control, you will actually find misspellings in the display. I'm not shocked the instruction has a detail incorrect.

pedmec

As i mentioned before you are losing ignition because i believe you have incorrect air/gas ratio. This is exactly how it acts when its not set up properly. I have fixed this issue by adjusting the inlet gas pressure.

First you need put your ignition speed back to factory settings. Turn in throttle adjustment screw until completely closed. Then turn throttle screw back out in 6 complete revolutions and try ignition. This general works. When you get ignition you will still need to fine tune with a combustion analyzer as you might be out of range and producing too much CO.

*this works as long as you haven't played with the offset adjustment screw.

pedmec

You need to check that gas valve model. 1 went to the dungs website for that valve. Its listed as a 24 volt gas valve. Never been crazy about Burnham tech support.

108882-01 It's for the 80b and 150b converts to dungs #gb-wnd-055. you can clearly see the voltage on the valve. its marked as 24 volts AC. Here is the page i referenced. you can get a pic of the tag up close.

http://bostonheatingsupply.com/108882-01.aspx

Jamie Hall

Unless that gas valve is really really strange and has some solid state components built into the valve -- which I would find odd -- it should work equally well on either 24 volts AC or DC. I'd love to see a circuit diagram of that harness plug which is claimed to convert AC to DC, though, if you would post it

Boilershepherd

I don't have any circuit diagrams for the valve.
I do appreciate the support but I cant get drawn into a discussion on whether or not the gas valve is AC or DC. All I can tell you is that I measured DC volts at the valve. Tech support advised me it was DC.
I can repost the tech support phone number and I'm sure they'll be willing to discuss it.

I was also informed that the lightoff fan speed has been updated from 3000RPM to 4000RPM for the newer control setup.

Here's an image of the gas valve.


I described above, the manipulation of the throttle screw did not change the results. Nor manipulating the air inlet to limit the air drawn in. As for 'what I have to do', I've done. I've run in the screw and counted rev's opening. Not a small amount of time was spent working on this.

I reviewed the link for the gas valve at boston heating supply. It would appear that the valve is compatible with the MCBA control. That control is not part of the controls in this specific boiler. This boiler uses the Sage 2 control.

The boiler is presently operational and being observed for malfunctions by the home owner.

I may not come back to this discussion to reply to further comments. Thanks again for the curiosity and thoughtful discussion.

Stay Warm.

Peterug13

We bought dozens of alpine boilers and i went thru the same thing with one of them. There is a diode in that gas valve cable. After a few hours of troubleshooting it was in fact that stupid cable