Boiler not firing (Happy Thanksgiving!)

matt9090

Good morning - my auto damper opens then closes and the boiler doesn’t fire. I’m getting 24VAC on the brown and black wire and get 24VAC on orange and black when heat is called but then that cuts off when the damper begins to close. I tried to jumper yellow and orange to close the switch but that didn’t fire the boiler. I replaced the aquastat last year and just inspected the solder connectors on the back of the board and they look fine. I’ve hit a dead end at this point other than putting a new aquastat in which would seem silly. The timing couldn’t be worse with the holiday. Any ideas? Thanks in advance!

unclejohn

Does the damper just make a continuous circle. Meaning open to close. There may be a hold open switch on the damper. 

matt9090

yes it opens and just keeps going till it closes - 180 degrees. I tried the manual hold switch when it’s open but that didn’t kick it on. 

Dairon421

Take a picture of wiring diagram and put it in thread. You may have jumped the wrong wire. You have line, load, switches and source in electrical. You already established that you have source power going to the boiler . Now check every switch inside the boiler and if you read 24v the switch is open and you need to find out why it did. If you get 0 volts across a switch it's closed. Next check power the loads . If you check the vent damper correctly than move to the next load in the sequence of operation like the gas valve (don't know what brand boiler you have). If you got power to a load and it's not coming on it's defective. If that fails you have a loose or broken wire somewhere.

Dairon421

Plus you said you getting 24v on both terminals on the vent damper when heat is call. Two wires is for the load side of the damper and the other two wires is for the switch side. If you got 24 volts across the switch side on call for heat it won't turn on because the switch is open 

pedmec

what kind of boiler steam or water. boiler make and model would help as different manufacturers use different colors on the wiring harness

matt9090

matt9090

It’s a Columbia gas boiler (water). Wiring diagram above. It might look a little jacked because the transformer went but I replaced it so the new one is mounted on the top and worked all last year like this. 

It’s an aquastat L8148 E 1265. 

Everything I’ve read on the Field control dampers has the brown and black as the line/load and yellow and orange as the switch. When I measure orange and black it reads 24 as the damper opens indicating the call for heat then cuts off when the damper starts to close.

matt9090

Oh and by the way - thank you all so much for responding on this holiday.

109A_5

Hello @matt9090,

matt9090 said:

It’s a Columbia gas boiler (water). Wiring diagram above.

That is a picture of your Acquastat wiring not a wiring diagram, the model of your Columbia gas boiler and the Damper unit might help. Below is a generalization based on limited information of your system.

Anyway blending L8148E info. and FieldControl info. I get this (pictures below). During a call for heat verify 24 VAC is constantly between TV and R and / or B2 and R. If OK verify 24 VAC is constantly between B1 and B2.

matt9090

matt9090

Sorry here’s the diagram. I’m glad y’all can read these. They confuse the heck out of me. I tested TV and R and get nothing. R appears to be ground? I also don’t get anything between B2 and R. 

Boiler is MCB125HID
Damper is RVG-PKS. 

109A_5

Hello @matt9090,

If TV to R predominantly shows 0 Volts, does the relay in the Aquastat pull in and stay engaged as long as the thermostat is calling for heat ? Since the Damper cycles and TV to R predominantly shows 0 Volts I would suspect the solder connections to the relay. May need magnification to see the solder connection defect. Flexing the circuit board with a non-metallic tool may confirm the loose or poor solder connections at the relay. The power needs to get through the Relay (at contacts 1K2) and the High Limit controller switch (B to R) for R terminal to be energized. The R then goes to the Damper to command it to open. Once the Damper opens it powers the S8600 to control the Gas valve and ignite the burner.

TV and B2 are probably referenced or bonded to ground by the S8600 and a green wire to the Gas valve.

matt9090

Turns out TV and R are at 24VAC when the damper first starts but when it is open and is 90 degrees the damper clicks and it keeps going and voltage drops to like 2-3V. Same is true for R and B2. 

Jamie Hall

I dislike those things -- for the reason you have found out: you don't save much, and when they fail, which they will, you get cold. Sounds like the switches in the damper which are supposed to stop it when it's open and then allow the boiler to fire are giving trouble. Can you lock it open manually? Some can be...

matt9090

For sure. I can keep it open with the switch but it doesn’t fire. I tried jumping orange and yellow and it didn’t fire. 

Steamhead

Have you checked the blocked-flue and roll-out (SSW and RSW) safeties?

matt9090

Looks like B1 goes straight to the ignition module terminal. Not seeing anything in between. 

109A_5

Hello @matt9090,

matt9090 said:

Turns out TV and R are at 24VAC when the damper first starts but when it is open and is 90 degrees the damper clicks and it keeps going and voltage drops to like 2-3V. Same is true for R and B2. 

You need to determine if the presents of 2-3 VAC is due to an overload of the transformer by the Damper and / or the S8600 and the Gas valve OR there is excess resistance at the Relay contacts at 1K2 and / or the High Limit controller switch (B to R).

At the point in the cycle that you measure 2-3VAC is there still 24 VAC at the transformer's secondary between TV to Z ? If there is excess resistance anywhere in the path the Voltage downstream from the resistance will be lower. If the transformer's voltage is normal I would suspect the resistance is too high at;
Relay contacts at 1K2
High Limit controller Switch (between B to R)
Bad solder joints where the relay connects to the circuit board.
I suspect the when the damper switch closes the additional load of the S8600 and the Gas valve is loading down the circuit due to excessive resistance inside the Acquastat. Which would explain when you jumper the Orange to the Yellow it still does not work.

By the way, if the transformer's secondary voltage is normal all the time, the time in the cycle when you are seeing 2-3 VAC between TV and R, the component with the excess resistance will have the balance of the transformer's voltage across it. Maybe like 21 - 22 VAC if your transformer is actually right at 24 VAC.

Or is it 2-3VAC is because the transformer is being overloaded (although in this case I would suspect the relay to buzz).

Steamhead

matt9090 said:

Looks like B1 goes straight to the ignition module terminal. Not seeing anything in between. 

Look again- you'll find those two safeties.

109A_5

Hello @matt9090,
Here is a link to the manual of your boiler, this will show you physically where the safety limit switches are located (Roll-Out Safety Switch and Blocked Vent Safety Switch). Page 18.
https://1728condo.files.wordpress.com/2016/07/columbia-boiler-operations-manual-mcb-manual.pdf
If either is open (or tripped) the boiler should not fire. They may be wired in somewhere else or just missing. Like (apparently other drawing errors) the High Limit controller micro-switch R and B terminals on the Boiler's wiring diagram seem to be labeled in reverse to the L4183E Honeywell drawing and your picture.

However (to me) those safety devices if tripped do not explain the rest of your symptoms.
In this picture the safety limits are encircled in Red and the actual defect I believe you have is encircled in Green, which may explain the 2-3 VAC when 24 VAC (Blue-ish text) should be present during a call for heat.

matt9090

You’ve given me a good bit to look at. I went back and measured a few things. The voltage from the transformer is 26.5. I replaced the original aquastat transformer last year after it went up and just bought a standard transformer (not the exact aquastat replacement cause I couldn’t find it). The boiler worked all of last year and some this year.   

The excess voltage is actually 1.88VAC after the damper begins to close. 

TV and Z are steady at 26.5

What should I see when measuring resistance at the relay and at the high limit switch?

You guys rock providing all of this info. I’m to the point where I might just drop the $300 for another aquastat. Should I stick with the same model or is there something better and more reliable? I’ve replaced the unit once and then had the transformer issue and now all of this. It’s all getting old!

109A_5

Hello @matt9090,
I prefer 'System On' Voltage testing since then you are working with the actual loads in the system and their current draw. Resistance measurements work too but the Ohmmeter is the power source and usually provides less current for the test than the circuit normally works at. This can produce confusing results for some folks.

Anyway, in this case since your Boiler is probably stone cold, turn the 120 VAC power off to the boiler !!! The resistance across the High Limit controller micro-switch R and B screw terminals should be less than an 1 Ohm or basically the same as the meter probes touching each other. Also the Relay contacts at 1K2 should be less than an 1 Ohm. You will have to manually close the relay contacts by pushing the black plastic contact mount towards to rest of the relay (near the blue spring). **** This may cause a false result since you are putting pressure on the solder connections to the Relay. **** I would measure between Z on the board and B High Limit controller micro-switch.

!!! BE Sure !!! to turn the 120 VAC power off if you are sticking your finger in there !!! The other set of contacts controls the 120 VAC Circulator. A non metallic tool would be best.

For me a better way, with the power on and a call for heat, I would just use the same two measurements just mentioned and their test points to test for the balance of the missing 24 VAC during the part of the cycle when it acts up (your Meter in AC Voltage mode). That way you don't have to stick you fingers in (since the thermostat is energizing the relay for you) and you are looking at the circuit defect happening with real loads through the contacts and the resulting Voltages.

In other words closed contacts 'On' (very low resistance) is needed to fire the boiler, you should have no Voltage across the contacts. Bad contacts with high resistance will have Voltage across them.

Also keep in mind with either method of testing the relay contacts 1K2 as I described this includes the solder connections on the circuit board for the relay. If the relay solder joints are bad they can be re-soldered. I have enhanced the Relay solder joints by removing the old solder and wrapping the Relay terminal with wire like thermostat wire and having both ends of the wire going back to the circuit board and then solder the whole joint. The wire bridges and enhances the gap the solder fills to make the connection between the relay terminals and the circuit board.

And yes, if what I believe is actually true in your case replacing the Aquastat would repair the problem. I just like to prove it first, Test don't Guess. Or just repair the bad solder connections if so (very common).

If you replace the Aquastat save the transformer, you may need it some day. There are other Aquastats, I don't know if you would like them any better, check out https://www.supplyhouse.com/

matt9090

I was away for the week so sorry for the delay. I think I found something. I measured the resistance between the closed contacts and got 13ohms. Between Z and B was 0 ohms. Voltage on the relay contacts was 150VAC and I had no voltage betweeen Z and B when it called for heat BUT when the damper hit halfway and started to close I got 16VAC. Not sure what any of this means though… 

109A_5

Hello @matt9090,

matt9090 said:

I measured the resistance between the closed contacts and got 13ohms.

Which contacts was this reading on ? 13 Ohms is way too high.

Voltage on the relay contacts was 150VAC

This sounds like you were on the circulator contacts 120 VAC + the transformers secondary voltage or at least one probe was placed wrong.

no voltage betweeen Z and B when it called for heat BUT when the damper hit halfway and started to close I got 16VAC.

Sounds like the Relay contacts 1K2 or the solder joints to the Relay 1k2 contacts are bad. Since the Aquastat is only a year old my bet would be on the solder joints.

matt9090

Just rechecked and B and Z are reading 13ohms. The 150VAC was the the contacts on what I thought was the relay (the thing with the blue spring). I’ll post a picture of that. 

matt9090

109A_5

Hello @matt9090,
The relay has two sets of independent contacts one for the 24 VAC stuff above the blue spring I believe in your original picture, and a set for the circulator 120 VAC below the blue spring. You probably can get both probes poking in where the original transformer was.

109A_5

Hello @matt9090,
Going by what you circled you were measuring two different circuits. Look at the Relay from where the original transformer was you may be able to see both contacts for the 24 VAC circuit.

matt9090

Ah whoops. Are you talking about the contact with the little red wire soldered on? I measured that and the closed contact (top) and got 2 ohms

matt9090

109A_5

Hello @matt9090,
The left circle in this picture is the two blurry contacts. The right circle is one wire to the coil of the Relay.
The blurry contacts when touching each other should be 0 Ohms assuming your Ohmmeter zeros at 0 (the probes touching each other)
During a call for heat the Relay makes these contacts touch each other and there should be no Voltage between them.

The Red arrows are the contacts. If you can I would probe at the Yellow arrows, when the Relay is energized, measure the Voltage. If the Voltage here is zero (Relay contacts) and the Voltage between B and Z is 16 VAC (or basically greater than 0) the solder joints are probably bad.

109A_5

Hello @matt9090,

matt9090 said:

Ah whoops. Are you talking about the contact with the little red wire soldered on? I measured that and the closed contact (top) and got 2 ohms

The 2 Ohms may have been the Ohmmeter seeing the secondary of the tranformer depending on where you actually had the probes. And if your Ohmmeter actually zeros at less than an Ohm.

matt9090

Yellow arrow contacts are zero volts and B and Z started at zero until the damper was open then started to close and then it was 16VAC. The contacts at the yellow arrow stayed at zero. 

Sounds like this confirms the solder joint is bad. Would that be the one the yellow arrow is point to? If so so how do I resolder them (I’ve soldered before - just want to make sure I do the right thing on the board)

109A_5

Hello @matt9090,

matt9090 said:

I replaced the aquastat last year and just inspected the solder connectors on the back of the board and they look fine.

The Yellow arrows just point to the location leaf spring that holds the contacts at the point where it goes into the plastic Relay base (for measurement purposes). I would not expect solder there. The solder would be on the solder side of the circuit board behind where those leaf springs come out as pins from the base of the Relay.
You stated you checked there, however bad solder connections may need magnification to spot sometimes. If you can I would re-flow these joints. The solder joints can be made more robust by removing the old solder then adding a small wire wrapped around the pins coming from the Relay base and extending the wire to the circuit board and soldering the whole thing.

matt9090

I resoldered those pins and now I don’t get voltage on B and Z at all which I think is good? The damper keeps spinning though. When I jumpered orange and yellow at the damper to take it out of the equation the relay started going nuts and saw a bit of a spark. 

EdTheHeaterMan

IMPORTANT EDIT
I meant to say R on the aquastat switch.

To find out if the Damper is defective and the L8148 is good, Lock the damper open, place a jumper wire between R on the limit and B1 on the board, where indicated in yellow.

This will bypass the damper end switch. If this operates the burner, then the damper is the problem. If the L8148 does not operate the burner in with the yellow jumper in place, then the L8148 is defective OR the spill switch or roll-out switch is open.

The yellow jumper is needed because once a L8148E 1265 is connected to a damper, there is an internal fuse that disconnects the R from the aquastat to the B1 on the board. A safety feature to prevent someone from operating a boiler using the plug in bypass jumper just in case they are not smart enough to lock the damper open or better yet, remove the damper.

109A_5

The Damper may have its own issues. I never assume there is only one problem, usually there is only one issue but if you rely on that mindset you will get tripped up at some point.
Sounds like you may have made a solder bridge to another part of the circuit. I would re-check the soldering job. The Relay buzzing probably means the transformer is overloaded when the relay connections close. Or the function of the Orange and Yellow wire are not what we believe them to be.

109A_5

Can you manually open the Damper and then disconnect the damper cable to the L8148E and jumper B1 to R ?
Does the boiler fire up with a call for heat ?

EdTheHeaterMan

109A_5 said:

Can you manually open the Damper and then disconnect the damper cable to the L8148E and jumper B1 to R ?
Does the boiler fire up with a call for heat ?

You can connect B1 to R on the Aquastat switch as indicated on the photo above.
Then the L8148 can be used automatically for the rest of the life of the control.

It appears that this control will have 9 lives as long as @matt9090 has a soldering iron

109A_5

EdTheHeaterMan said:

109A_5 said:

Can you manually open the Damper and then disconnect the damper cable to the L8148E and jumper B1 to R ?
Does the boiler fire up with a call for heat ?

You can connect B1 to B on the Aquastat switch as indicated on the photo above.
Then the L8148 can be used automatically for the rest of the life of the control.

It appears that this control will have 9 lives as long as @matt9090 has a soldering iron

Won't going to B instead of R bypass the High Limit Controller switch depending on which wiring diagram you believe? OK for a test but not good for normal running.