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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8386
Experience:  Furnace, A/C and heat pump specialist.
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I have a Gaffers and Sattler S80FDF furnace that all of a sudden

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I have a Gaffers and Sattler S80FDF furnace that all of a sudden stopped working. Replaced the thermostat since it was real old anyway and still nothing? Any advice???
graphicHello.Sorry you are having problems. My name is XXXXX XXXXX I will do my best to help.Please wait to leave rating until we are finished.It may be difficult to find a manual on the furnace but I will try to help.If I can not help, I will open to other experts. First can you do some hands on troubleshooting and do you happen to have a voltmeter for troubleshooting?
Customer: replied 4 years ago.

Yes I do.

OK good. Now let me get a bit more info. Does your thermostat have FAN /ON or AC ? And if so will either of them come on or do e get nothing at all?
Customer: replied 4 years ago.

It has fan/on and getting nothing at all. Pilot is lit and the fan is working when I manually turn on the fan switch at the furnace.

OK lets do this. Remove wires from thermostat and twist R and W together or loosen R wire and slide W wire in same terminal so R and W are connected and see if we get anything.
Customer: replied 4 years ago.

Did that...still nothing

Ok, now remember I don't have a manual, so I am going to be doing some of this as general troubleshooting. To start with, How old would you say the furnace is and does it have a control board on it? If so any led lights that might give us a flash code(error code)?

Customer: replied 4 years ago.

It is real old so no led lights. I would say it is from the sixties.

Yeah, that is about age I expected it to be. So we just have to go a step at a time. Lets go to the furnace and locate the transformer.graphicOn low voltage side we will have two wires. One is common and goes straight to the gas valve, fan relays, etc. The other goes to R at thermostat and comes back from thermostat on W when thermostat calls for heat. So lets start by making sure we have a circuit closed to that point. In other words determine which is COMMON. Put one meter lead on it. The put the other meter lead on the white wire coming back from thermostat and on call for heat we should read 24 volts between common and white. We will go from here.

Customer: replied 4 years ago.

Just to confirm what setting should the multimeter be on... DCV 20?

No we need to be on ACV 200
Customer: replied 4 years ago.

ok put it on ACV200 and it is reading between 25.8 and 25.9

Excellent great job. Now we know that transformer is good and thermostat is doing what we want. The issue has to be between here and the gas valve.Trace where that white wire goes to next and whatever component is there, we need to check on the terminal out of that component to see if that is where we are losing voltage.Where does white wire go next? Maybe a limit?graphic
Customer: replied 4 years ago.

Yes...I put one meter lead on the component (blk wire) and one on wht wire and it is reading 26.4. P.S. the gas valve where the other wire goes to is really hot.

Does this unit have a standing pilot(Stays lit) ? And is on if so? If you have 24v (the 26.4 is ok). the gas valve should be opening .
Customer: replied 4 years ago.

Yes, has a standing pilot and it is lit.

This is pointing to a defective valve. Do you have a combination fan/limit control like this with a dial?graphicAlso how many terminals are used on the gas valve?

Customer: replied 4 years ago.

It is quite a bit different but yes and the fan control is set at 110.

You don't have a dial on it that you can gently turn to see if blower will energize do you
Customer: replied 4 years ago.

There is a dial that says "fan off temp" and goes from 60-130. I tried to turn it both ways and nothing happened.

Yes, that one doesn't quiet work the same as the picture I sent. Now back to the valve.Are there only 2 terminals used?
Customer: replied 4 years ago.

Yes 2 terminals

ok. At this point I am going to diagnose as being defective. If we are getting 24 volts to valve, it should be opening
Customer: replied 4 years ago.

So it is a defective gas valve??? Also can I replace it myself and do you know the price range for a new one?

If you can get the model off of the valve, we can Google it to locate one

Customer: replied 4 years ago.

McCorkle 24v 60cycle .42amp 1/2 psi Model#V472. That sound right?

OMG. You will probably not be able to find a MCCorkle valve.The best thing to do is going to be to remove the valve and take it to a local hvac or appliance parts house along with the input rating of the furnace and get them to match it with a universal replacement Robertshaw .Honeywell or White Rogers valve.
Customer: replied 4 years ago.

ok thanks for all your help.



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