I have an old Tappan model SGUF140D48E7, s/n 77 19739 140,000 gas furnace. I'm having trouble finding the furnace high limit setting, and fan on/off settings. The range of the old high limit was 170-210 F, and the fan range was 80-120 F. Can you tell me what the correct high limit and fan on/off settings should be? The manufacturers plate indicates temperature rise is 70-100 F
Most high temp limits, gas fired, are a 195°f. Most fan on, gas fired, are 100-120°f. We allow the heat exchanger to warm to a temp before allowing the blower to operate. This prevents "cool" air from blowing upon initial start up, so that 100-120 is a variable. The 195° is a safety factor, but I've seen some at 215° due to improper ductwork/air restrictions. 195° is a factory setting.
Possibly it had the 70 on it and someone bumped it up already. I'm uncertain, I'm a straight cool/ minimal heat pump tech in SWFL. I am certain 10 degrees isn't hurting anything, replace with what is in there.
If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79
SOURCE: MHU 75 Model Mr. Heater
The roll out switch is a small disc shaped part about the size of a nickle. There may be more than one. anyway there is a button shaped like a small peg in the center if it, push it in and it should stay in. You may need to re examine the limit switch, because this is what it sounds like. they are rated for a set temperature, so your application may need a higher temp. A simple way to check parts like these is to by-pass them by taking the wires off the part and connecting them together. If this solves the problem, that it. My only concern is that this is a new installation, and maybe its not venting adequately or its burning up all the usable air in the room. That's why most of these parts are on the equipment.
SOURCE: Fan switch will not make (limit switch).
If the snap switch is not located close enough to the plenum, this can be problem. The other option would be to cover the switch area with a metal shield or liatherm paper (fire rtardant paper).
SOURCE: Have an older model Tappan furnace. I have
they make a specific one for this unit,but first check and make sure its not being blown out by too much down draft from the exhaust stack or a fan on the unit,watch it when it shuts down and see if the flame gets blown out or just goes out by itself
SOURCE: i have an olsen oil furnace, the problem is the
Hello A couple of things.If burner is cycling on high limit ,it can be a air flow problem.Change the air filter.Check the blower wheel that is reasonbaly clear/clean.Also check the intake grille that it is not blocked and all the supply grilles are open.Also mabey the nozzle size can be steped down if the input is too high(a slightly smaller fire).If the blower fan on/off is the problem (as the burner is seperate) raise the 120*f pin to 130*f but hold the wheel disc steady during adjustment.Leave the 90*f at 90*f.
SOURCE: With the Dometic 3106995.032 thermostat fan switch
Hi, the wiring terminations are near consistent with a 24 volt ac furnace and I will tell you how a 24 volt stat is terminated. RC= 24 volts jumped to RH for red wire only. This would be for a central system with air and heat. W=white for heat, G= Green for Fan, and Y = yellow for cooling. I do believe it is wired correctly for your application. Please verify your units model and serial number and give me a clue as to what is taking place, and did you change the thermostat or make a part change?
Sincerely,
Shastalaker7
A/C, & Heating Contractor.
121 views
Usually answered in minutes!
×