Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Boiler not firing (Happy Thanksgiving!)

matt9090
matt9090 Member Posts: 11
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!

Comments

  • unclejohn
    unclejohn Member Posts: 1,778
    Does the damper just make a continuous circle. Meaning open to close. There may be a hold open switch on the damper. 
  • matt9090
    matt9090 Member Posts: 11
    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
    Dairon421 Member Posts: 68
    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.
    ScottSecor
  • Dairon421
    Dairon421 Member Posts: 68
    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
    pedmec Member Posts: 623
    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 Member Posts: 11

  • matt9090
    matt9090 Member Posts: 11
    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
    matt9090 Member Posts: 11
    Oh and by the way - thank you all so much for responding on this holiday.
  • 109A_5
    109A_5 Member Posts: 389
    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.







    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • matt9090
    matt9090 Member Posts: 11

  • matt9090
    matt9090 Member Posts: 11
    edited November 24
    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
    109A_5 Member Posts: 389
    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.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • matt9090
    matt9090 Member Posts: 11
    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
    Jamie Hall Member Posts: 19,889
    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...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SuperTech
  • matt9090
    matt9090 Member Posts: 11
    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
    Steamhead Member Posts: 15,636
    Have you checked the blocked-flue and roll-out (SSW and RSW) safeties?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • matt9090
    matt9090 Member Posts: 11
    Looks like B1 goes straight to the ignition module terminal. Not seeing anything in between. 
  • 109A_5
    109A_5 Member Posts: 389
    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).

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Steamhead
    Steamhead Member Posts: 15,636
    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.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • 109A_5
    109A_5 Member Posts: 389
    edited November 26
    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.




    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • matt9090
    matt9090 Member Posts: 11
    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
    109A_5 Member Posts: 389
    edited November 27
    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/
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System