Boiler not firing (Happy Thanksgiving!)

matt9090

I thought a “lamp” was some fancy electronics thing. Not an actual lamp haha. Whoops. Anyway, I connected the lamp to B1 and B2 and it did not illuminate but the damper spun around. When I jumped the damper line to bypass it, the lamp illuminated. 

matt9090

Curious about what the lamp test revealed. Meanwhile I figured out that S8610U is a valid replacement for my S8600M1013 and since mine is probably 24 years old it’s worth the $160 on Amazon to replace it - especially if it keeps messing with the Aquastat. 

Manual for reference:

https://documents.alpinehomeair.com/product/S8610U3009%20Installation%20Instructions.pdf

matt9090

One additional thing - I just went and measured the voltage of B1 and B2. When the damper is bypassed/jumped I get 26VAC. With the damper connected and spinning I get 4.5VAC. Not sure what this might mean. 

109A_5

Hello @matt9090,
Using the light bulb as a substitute load, basically replacing the igniter control module (S8600) and Gas valve. The Aquastat and Damper should have worked normally.
Thermostat call for heat
Aquastat relay energizes
Damper turns and stops when open
Damper End switch closes
Light bulb glows constantly (dimly) (simulating constant power to the S8600 to operate the Gas valve and provide ignition)

It appears from here that the S8600 has been drawing excessive current (for a while now), it beat up and damaged the End switch in the Damper and the Solder joint in the Aquastat and maybe the old failed transformer.

If VR1 in the S8600 (a power input protection diode) failed as @Peter_26 suggests the rest of the S8600 may be fine it just draws too much current (because of VR1) damaging the other devices.

I'm guessing your wired in transformer is a higher VA rating and it tolerated the abuse better that the original transformer in the Aquastat.

Sadly by design there is no protection fuse on the secondary of the Aquastat's transformer (you could add one with your wired in transformer setup, 3 amp is common (or a much lower current fuse on the primary side).

Also if you want to just leave the Damper open or remove it you could replace the Pico Fuse in your present Aquastat for a few $ and use the factory Damper bypass jumper and not replace the whole Aquastat. You would have to remove (desolder) the Green Pico Fuse from the Aquastat and verify its rating, maybe 3 Amps and replace it.
One source of 3 Amp Pico fuses for example.
https://www.digikey.com/en/products/detail/littelfuse-inc/0251003-MXL/700737

The S8610U would probably work too it just has extra features you probably don't need.

matt9090

Thanks. After all of this I’ve convinced myself it’s time for an overhaul. I am going to replace the S8600 and get a replacement damper board and motor. $260 for both components. I am then going to follow the diagram and fix B1 and B2 to the controller. At this point I’m even thinking about just doing the aquastat. Basically a clean slate assuming the gas valve and limiters are still fine. Just under $600 and hopefully headache-free for a lot of years. 

EdTheHeaterMan

And if you find all those parts don't solve the problem, where will you look next?

matt9090

Good question. I guess I’m hoping for the best. At that point there isn’t much left unless I’m missing something. Not sure how to get past where I am without at least swapping the control unit. 

EdTheHeaterMan

I would use "Known Good" components to test all the other components.
For example. You have a working 24V transformer. When 24 Volts is applied to 24V and 24V GND on the S8600, the ignition control and gas valve should operate. I wonder if that test was performed? I tried to look at all the comments and did not see that it was done.

Of course this is only a test and can not be left that way. Because there are no safety features in place with this test. No temperature limits on the water, flue gas, or flame rollout. But it does verify that the ignition control is not at fault and the gas valve is not at fault.

There is a lot of theory being discussed about possible bad solder joints on different components. if resisters, fuses and diodes are within expected parameters. But the bottom line is, does the ~24 VAC get from the transformer to the gas valve? That answer is NO. So use the process of elimination to find out what is stopping it.

Try my test and then we can go to the next step.

As a precaution, I might add this to the transformer to protect it and keep all the smoke from getting out



There are 3 amp circuit breakers available to do testing like this.

matt9090

I appreciate that and can definitely give that a shot. That is something I haven’t tried. 

109A_5

Functionally that test was done, (the wire from B1 going to the S8600 connected to Z) @matt9090 claimed it made something Hum louder, I assume the transformer.

Basically the only fundamental test that was not done is to apply 24 VAC directly to the Gas Valves and verify Gas Valves functionality with no ill effects.

matt9090

I thought about that and realized I connected B1 which was the ground. I need to try B2. You suggested B1 before I confirmed my wiring doesn’t match the schematic. 

EdTheHeaterMan

109A_5 said:

Functionally that test was done, (the wire from B1 going to the S8600 connected to Z) @matt9090 claimed it made something Hum louder, I assume the transformer.

Basically the only fundamental test that was not done is to apply 24 VAC directly to the Gas Valves and verify Gas Valves functionality with no ill effects.

Functionally and actually may not be the same.

The test should be done with no other wires connected to 24V and 24V Gnd.

EdTheHeaterMan

Try this.

matt9090

Ok I did this and the controller just started buzzing. No ignition. 

EdTheHeaterMan

Sounds like the controller is bad. unless the 24 volts is backwards and there is a short circuit happening. Try reversing the R and the C. with no other wires connected to the transformer R and C

matt9090

Same result. I think it’s the original from when the boiler was installed in the late 90’s. I’ll feel comfortable replacing it regardless!

EdTheHeaterMan

There is a remote possibility that something zapped the boiler and caused the damper and the ignition to fail. If that is the case, the gas valve and aquastat relay may also be damaged. Was there any power outages, lightning strikes close by, or other power irregularity on thanksgiving?

109A_5

Hello @matt9090,

matt9090 said:

I thought about that and realized I connected B1 which was the ground. I need to try B2. You suggested B1 before I confirmed my wiring doesn’t match the schematic. 

That does not matter since the 'Ground' is bonded through the S8600 via the green wire to the gas valve. So every thing else is 'Floating'. Connecting the wire that was on B1 to Z just bypasses the Aquastat's and Damper's controls applying 24 VAC directly to the S8600. There is no controls or switches in-between B2 and the transformer.
In this case the 'Ground' really does not matter except if the wires from the Aquastat to the S8600 were compromised to the jacket of the boiler or another grounded metal piece, and you inspected the wires and the limit switches and found no defects. The 'Ground' bonding is needed for the Flame Detection functionality.

Switching the wires B1 and B2 probably does not matter much as for the actual electrical operation. It just makes it more confusing since it does not match the wiring diagram.

HomerJSmith

Boiler not firing (Happy Thanksgiving!

Looks like you got a turkey. Sorry for the joke, I couldn't help it.
Lightening strikes can be 1/4 mile away and still do a number on electrical component in the house. Anything else in the house, electrical, fail? I always put a computer grade surge protector on Mod/Cons.
In my experience, I have come across solder breaks on the back of the boards in ignition modules and aquastats relay connection to the board. The aquastat has 24Vac and a 115Vac circuitry in it which must be separated, it is with fish paper (insulative cardboard). If you decide to take the board out of the aquastat, disconnect power from the boiler, to check the relay solder joints, remember the fish paper and be careful you don't ground the capillary tube to the temp bulb in the well to the 115Vac connections when putting it all together. A grounding will blow the whole capillary tube open.
The relay has 2 poles, one for the circulator and one for the 24V thermostat boiler safety circuit of which the damper and igniter are a part.

matt9090

Well, after the insane amount of troubleshooting and suggestions I tested the gas valve which worked great, replaced the aquastat, controller, and damper and everything is working beautifully. I didn’t connect the damper yet but at least wanted to have the option to connect it up. I know it will blow the fuse on the aquastat so didn’t want to commit right away. The controller and aquastat are Resideo brand and I hope they hold up. They were all I could get quickly on Amazon. 

Anyway, I cannot thank you all enough. I especially want to thank @109A_5 who spent an inordinate amount of time working with me, even on thanksgiving. Also @EdTheHeaterMan for pushing me to do extra tests. 

I’m amazed by the amount of voluntary support on here and wish I could buy you guys a beer. I also want to say I learned a ton about my system and about electronics which will only help me on so many things in the future. 

Many thanks and I hope to not have to bug you about anything any time soon (at least related to my boiler!!)

109A_5

Glad you are up and running, it's getting cold out.