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Old Weil Mclain No Spill Switch

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Stapes
Stapes Member Posts: 9
Hello,
I have an old boiler in the house we just moved into-Weil Mclain CGM-5 Series 6 (hot water/nat gas). The system does not have a spill switch on it, never did (not on wiring diagram). I would like to put one on as a safety measure (hoping to hobble through another heating season or two while we save up some money before we have to replace this antique). I found a parts manual Mclain put out in '16 listing parts for the CG series and it looks late later models used part number 510-300-014 (still available for later CGA and CGx models). Is there any reason this wouldn't work if I installed it on this boiler? Thanks for any thoughts. Best.

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited November 2022
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    That switch will work fine. You will need to connect one of the wires from the new spill switch to the wire that feeds one side of the roll out switch on boiler. Then place the wire from the other side of the spill switch where you removed the wire from the roll out switch. This will put the roll out switch in series with the spill switch.

    Unless you already have electrical circuit wiring experience and can find a closer wire to break the safety circuit.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • mattmia2
    mattmia2 Member Posts: 9,850
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    What makes you think you need to replace it soon?
  • Stapes
    Stapes Member Posts: 9
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    Thank you Ed, I appreciate your help.
    There is no rollout switch either hehe...it's a very straight forward series loop though. Line voltage to the transformer, then out to the t-stat, back to the gas valve, spliced to the relay. On call for heat, relay activates pump and and makes for limit switch then over to gas valve other post.
    I was thinking I would just install it between the limit switch and the gas valve. Does that sound right? Thanks again for your help and advice.
    Here is the wiring diagram, my photos of the actual wiring aren't very good.




    And Matt, regarding replacement I am not looking to replace it, just preparing for the possibility that it might, after many decades of loyal service finally spring a leak in the cast.

    Best,


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited November 2022
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    WOW That is an old one... no spill switch and no rollout switch. Adding those parts would add a small increase in the safety of that heater. I guess not enough people died from carbon monoxide poisoning when that boiler was built.

    Every code requirement, every safety part added, every new feature to increase safety in the world… was discussed, analyzed and debated over by a group of professional experts because... someone got hurt, property was damaged ,or someone died. The aforementioned experts were called to find out why an insurance company needed to pay an insurance claim, resulting from those occurances. They needed to find out a way to keep that type of claim from happening again. For example: The Hartford Boiler Insurance company requires relief valves on boilers and, that is why McDonalds coffee cups have "Contents Hot" printed on the side of them.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Stapes
    Stapes Member Posts: 9
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    Thanks for your thoughts Ed. A "small increase" in safety will be better than nothing, though I am thinking it will be more than a slight improvement, no?
    Do you know of an aftermarket rollout switch that would work on this boiler?
    Thanks again
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited November 2022
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    https://www.supplyhouse.com/Weil-McLain-512-050-230-Rollout-Thermal-Fuse-Element-228-C

    If you look at this CG series 12 boiler, the access door to the burner compartment #4 has a small bend at the bottom with a cut out and screw hole to hold the roll out switch #16 in the proper location to detect unusual roll out. You may be able to modify your door to accept the rollout switch.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • gyrfalcon
    gyrfalcon Member Posts: 167
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    Not to hijack this thread but this situation touches on my boiler’s age and components.  No roll out or spill switches.  Just cleaned and serviced with a clean bill of health but the tech did note that there is a lack of safety devices. I was thinking about the feasibility of adding safeties but not sure if it’s worth it before the old Slant/Fin Galaxy is retired. 😢
    Slant Fin Galaxy GG100(1986) , 2 zone hot water baseboard, T87 Honeywell thermostats. 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited November 2022
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    gyrfalcon said:

    Not to hijack this thread but this situation touches on my boiler’s age and components.  No roll out or spill switches.  Just cleaned and serviced with a clean bill of health but the tech did note that there is a lack of safety devices. I was thinking about the feasibility of adding safeties but not sure if it’s worth it before the old Slant/Fin Galaxy is retired. 😢

    It does not hurt to add safety devices to upgrade old equipment with modern technology. That is what oil dealers across the country were doing when oil burners were placed in coal heaters in the 1940s and when those burners were replaced with more efficient burners in the 1960s.

    Is it worth it? for something like a spill switch or roll out switch, there is no manual fuel shoveling or energy savings associated with those parts. The benefit is safety. Your old boiler has not needed those parts to heat properly for years, but the thing that causes those parts to operate can happen at any time. a bird or critter can fall down a chimney and block the vent at any time regardless of the age of the equipment. an event that causes soot to form and block the heat exchanger will probably never happen to your boiler, but if it does, you would have wished there was a roll out switch added.

    So how do you measure if it is worth it? That is a personal decision. What is life worth, What is health worth, What are you paying for insurance to protect those things?

    Yea, I would add them if I lived there.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    gyrfalcon
  • Stapes
    Stapes Member Posts: 9
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    Thanks again for all your help Ed and good luck gyrfalcon.
    Best
    EdTheHeaterMan
  • iridium
    iridium Member Posts: 12
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    Hi I have this same boiler. CGM-5 Series 6 in a rental house I am at. I was looking into the fact that I have no bypass valve in a gravity fed system with big cast iron radiators.... and came across this. Might be interested in whatever you end up doing here so keep us posted?
  • gyrfalcon
    gyrfalcon Member Posts: 167
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    Here is a picture of my gas valve, boiler, wiring diagrams and gas valve manual. I am going to undo the jumper on the ECO and wire in series, a switch at the draft hood and one burner access door.  I just need to find the appropriate switches. 
    Slant Fin Galaxy GG100(1986) , 2 zone hot water baseboard, T87 Honeywell thermostats. 
  • gyrfalcon
    gyrfalcon Member Posts: 167
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    @EdTheHeaterMan,  can you confirm if my thoughts are correct on adding safeguards in this way?  Can the ECO terminals under the thermocouple be wired in with roll outs and spill switches?  
    Slant Fin Galaxy GG100(1986) , 2 zone hot water baseboard, T87 Honeywell thermostats. 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited November 2022
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    Connecting in series with ECO terminals is equivalent to a manual reset safety device. A spill switch that has an automatic reset and a roll out that has an automatic reset will be in essence a manual reset. If you decide to select the single blow roll out switch then you can place it in series with the aquastat limit and get the same results. The general idea is to make you have no heat when there is a safety issue. Once you find the reason for the limit, roll out, or spill switch, creating an open electrical circuit, and you correct the cause, then you can relight the pilot or reset the manual limit and get back in operation.
    gyrfalcon said:

    @EdTheHeaterMan,  can you confirm if my thoughts are correct on adding safeguards in this way?  Can the ECO terminals under the thermocouple be wired in with roll outs and spill switches?  

    YES. Confirmed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    gyrfalcon
  • gyrfalcon
    gyrfalcon Member Posts: 167
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    Thank you , Ed. 
    Slant Fin Galaxy GG100(1986) , 2 zone hot water baseboard, T87 Honeywell thermostats. 
  • Stapes
    Stapes Member Posts: 9
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    Thanks again to everyone for their input and support.
    In response to iridiium here's what I ended up doing:
    I installed the Field Controls GSK-3 spill switch. It seems to be designed for installation on appliances which do not have a spill switch and provides good installation instructions. It can run on either 24v or millivolt applications. They recommend installing two switches 90 degrees apart on draft hood applications. I was happy to buy two in the name of safety. This switch was recommended by their customer support, it has a 180 degree set point. I suspect it could trip on a particularly windy night causing a false negative (er... um, false positive?-a false open circuit). The Weil McLain switch had a 240 degree set point I believe. We shall see but I figured I would start here with the lower trip temp. Still planning to install a rollout switch as well. Oh and I wired it as described in my post above.
    Best,