C.L Bryant model 140A gas conversion

farroutman2003

Looking for a manual, or any help with a C.L. Bryant Model 140A gas conversion for a Delco Model DB4W furnace. The pilot light is lit. When i turn the switch on to run the pump, i believe it should also turn on the furnace, but doesn't seem like it's firing the actual furnace. I'd like to check for power to the gas regulator, make sure that's working properly, just not sure what kind of voltage i'm working with here, and a wiring schematic or manual would be very helpful.

farroutman2003

Steamhead

@Tim McElwain ?

EdTheHeaterMan

I doubt very much if there is anyone with a wiring diagram for that system AND if there is, You will not likely find them. But there are some basics that must be understood and followed in order to get something like that approved for use in someone's home.. even back when that was built.

Look at the information on this identification plate. (Red arrow) This is the gas valve that opens and closes based on the thermostat call for heat
You will get 24 volts from a transformer R (upper right of the picture) that will connect to the thermostat then the limit then any other safety device like a rollout fuse or switch, then to the gas valve and from the gas valve back to the source... the transformer C.

Depending on the age, there may be a constant pilot that is controlled by a manual valve only. Not up to code by today's standards, but that will not automatically stop the flow of pilot gas if the flame gets blown out. Since it is pilot gas only and it is vented to a chimney, the thought was that there is not enough gas from a pilot to build up and explode… back in the day. We know that is not altogether true now, so those pilots are no longer offered on appliances like furnaces and cooking stoves.

The main burner safety control is the thermocouple. The end of the thermocouple is in the path of the pilot flame. If the pilot flame blows out, the thermocouple will not sense the heat of the pilot flame. No flame >>> no main burner gas. So you may have 24 volts to the gas valve but a bad thermocouple, so the gas valve will not open.

But it is really time to get a new furnace installed next summer.

The files below are what you might find as the wiring diagram, if there was one to be had. One is a boiler the other is a furnace

farroutman2003

Thank you, i'll give those a look. That info is enough to get me started though so much appreciated. So from what i'm seeing in that diagram, i have hot, neutral and ground on the 120v, that feeds into the transformer, that supplies my 24 volts that should go to the rest of the controlling system elements, thermostat, safety measures etc...

mattmia2

can you take a picture of the rest of the gas train? is there a safety valve just out of frame at the lower right of your picture? is there a rest button on it?

farroutman2003

i'll be going over tomorrow morning to do more checking. I've never been over there with actual tools so i haven't gotten to really look inside the main housing or check the severely old wiring. Now that i know the voltages i'm working with though, i'm good to do some further investigating, so more pics will be coming.

mattmia2

I think there is a safety valve at the lower right before the regulator that is only powered by the thermocouple. If it is what i think it is there is a button on it that has to be pressed to open it after the pilot is lit. the way it is positioned the button may be facing the floor. If it won't stay reset the thermocouple may be bad or not positioned correctly in the pilot flame or the pilot burner might not be burning correctly.

farroutman2003

so with some clever timing and live picture, the after shot i was able to capture a little more of the gas line assembly.

mattmia2

What we need to see is like here

farroutman2003

Soooo... it was the reset switch for the thermocouple. I forgot about those and since it was on the bottom, i didn't see it. out of site, out of mind. The gas had been turned off, and pilot light restarted, i'm guessing gas companies will only light a pilot light so they can't be held liable for anything else.
That all being said, many thanks for the responses and the diagram. Being an information site, the only way i can think of to properly repay is to end this with the pictures. Hopefully they'll help someone else some day.

farroutman2003

farroutman2003

farroutman2003

farroutman2003

mattmia2

farroutman2003 said:

The gas had been turned off, and pilot light restarted, i'm guessing gas companies will only light a pilot light so they can't be held liable for anything else.

When I had a furnace with controls like that the gas company tech absolutely knew how to reset the Baso switch.


You know how to drain the compression tank, right?


What is that pump on the floor for?

EdTheHeaterMan

In the diagram I offered you, the gas valve has a pilot safety that will turn off the pilot gas and the main burner gas if the pilot flame goes out. The thermocouple generates electricity from the heat of the pilot flame. Just enough electricity to keep the pilot safety from dropping out. But not enough to open it on its own. That is why you need to push the valve open and wait until the thermocouple gets hot.



In your Bryant, the pilot safety RED ARROW is separate from the main valve GREEN ARROW that operates on 24 volts. So the idea of the limit controls in series still holds to be true.

EdTheHeaterMan

WOW... You have a Honeywell series 10 (3 wire) switching relay to operate the circulator. R132A Series 10 controls employed a holding circuit in order to get a long enough differential from the Bimetal thermostats. W>B would pull in the relay. Since the Bimetal quickly warmed up and the contact opened there was a second contact connected to W>R that held the circuit for more temperature range, in order to eliminate short cycling. This is a classic control.

See the holding circuit in the Red oval

Although difficult to see, this might be the diagram used to originally connect your heating system's controls



What does the thermostat look like?

farroutman2003

upright thermostat, half dial at top. temp guage is in the center of housing running top to bottom. about an 1.5 in x6 inches tall. I believe... not positive.. the pump runs or ran to a radiator on the 3rd floor. I noticed when i was checking them all for heat that it was a different style radiator, thin finned as opposed to regular looking radiators. When following the line from that pump, it runs to a place in the basement ceiling that would really only make sense to be for that radiator. i'm guessing the pump would be to assist in the extra floor climb? about all i can think of. I like how simple things were back then, on or off. working or not. The problem with that simplicity is, it's no longer available. My dad kept this alive for years.

EdTheHeaterMan

Sounds like you may have the original Series 10 thermostat. Art Deco period. kind of reminds you of the Chrysler building in NYC

EdTheHeaterMan

The Round Aquastat appears to be a Honeywell series 40 control. That means it was designed for line voltage control circuits.

As I Recall
Series 10 controls were low voltage (24 VAC) with a holding circuit W was common R was holding and W was starting. (the way to remember series 10 was Will Begin for the starting circuit and Will Run for the holding circuit

Series 20 controls were poser open and power close type devices. R was common and R>B contacts made on temperature rise and R>W contacts were made on temperature fall

Series 40 controls were line voltage controls. They were not as accurate for thermostats, but for Fan, Limit and Circulator controls they were the go to choice.

Series 80 were 2 wire controls. R and W for heating. would be connected to W and B on the Series 10 controls.

But that is more information than you really need. You have the Series 10 controls from the thermostat to the switching relay. 3 wire R W B. The Series 40 aquastat and the strap-on (probably a L406A or L406B) can be used on line voltage or low voltage is operating the burner to maintain a minimum temperature for Domestic Hot Water coil. Even if it was disconnected years ago, unless someone rewired and re controlled it when the coil for DHW was abandoned, the boiler does not know how to stop making DHW. That could be a possible energy saving project.

EdTheHeaterMan

So step 1 is to see if you push the button on the Pilot Safety valve when the pilot is lit and see if it stays open I think it is on the bottom.
Or does it just pop back to closed?

If it does not stay open, then try to replace the thermocouple
https://www.supplyhouse.com/Resideo-Q390A1061-36-Thermocouple?_br_psugg_q=36+inch+thermocouple. It is available locally at most Plumbing Supply Companies. It is the copper wire looking thing in this picture the goes into the fire box.

farroutman2003

Sorry if you missed it, and appreciate the extra information. Definitely screen shots. Before the pictures i mentioned that the thermal couple hadn't been reset. All working fine now. Going back in the morning to get some readings, bleed the radiators of air. I remember doing all that as a kid. My problem was really i could see that 120 was going into it, and i suspected it ran thru the interior of the unit to that transformer, but can't take that panel off to see as the gas pipe runs thru it. That is pretty much the thermostat you posted in the picture. Fun to look back and see how things were done back then.

mattmia2

The rest of that system is gravity. that circulator was added to use a different type of emitter with forced circulation.