Question about Sterling RF75 Natural Gas Heater (75,000 BTU)

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The Sterling QVF 75 furnace lights and heats up, but the fan does not come on, or comes on after it heats up and shuts down. Can you help?

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Posted on Jan 02, 2017

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SOURCE: electric furnace/heater pump/fan unit won't shut off

There are dip switches on the main board.. When you remove the lower panel on the air handler there are instructions to where the dip switches should be for your units fan control. if the switches are in the correct configuration.. The Thermostat may be malfunctioning or not wired properly. and last.. and most expensive.. the motherboard may also be failing.

Posted on Jan 12, 2009

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SOURCE: M Sterling Model QVF-45 cuts out when it gets hot.

what does do / not do

Posted on Jan 29, 2010

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SOURCE: main burner comes on and

There could be a couple of different things happening...
The most likely is that the high limit switch is bad and the flame causes it to bring on the blower and then shuts the flame down also...this could be because the high limit is bad or because the vent is blocked and the flue gases are not venting...

Could also be a bad/dirty flame sensor, but that is not as likely...

I would checkout the high limit and find out what is going on there...


Posted on Feb 02, 2011

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SOURCE: sterling overhead garage furnace Main burner

you have two sencors for this heater hi limit and low limit try jumping then out one at a time see if this lights

Posted on Mar 27, 2011

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1 Answer

Where to look from here?

It sound like the limit switch is shutting off and not coming back in to play .

Mar 14, 2017 | Heating & Cooling

1 Answer

Bought a sterling 75 c garage heater burner lights but then 24 v transformer burns out

I didn't find that model but did see a pretty standard wiring schematic for Sterling garage heaters in one installation manual. I'm sure they didn't change much. I did notice they use a 50va transformer, not 40 which is likely what is getting used now. Don't think that would fix it, just an idea. Put a 5 amp fuse inline on the red side of the secondary side of the transformer. This will protect it. I'm willing to bet the ignitor section on the low voltage common is wired wrong. Remove the tstat wires, buy a resettable fuse and install it first. Then get the fan running first. If there is a g terminal jump red to green. This is fan only, start simple, hope this helps

Jun 18, 2017 | Sterling RF75 Natural Gas Heater (75,000...

1 Answer

I have a sterling overhead heater QVF-75.Pilot fires up and main burners also.Fan does not start.I took fan off and found will run with direct power.I took thermal couple off and tested and it opens and...

It's called the blower activation switch. It turns the blower on, when the heater reaches the proper temperature. The Thermocouple has nothing what-so-ever to do with the blower. It's simply a safety device for when the pilot goes out for some reason, it stops the gas from reaching the pilot. In other words, it locks up the gas control valve.

Most of the time, a "Limit Switch" stops the heater form overheating by shutting it down. However , these Sterling Heaters can be a little strange at times and what I would consider a limit switch, could be something different for Sterling. Check you Owners Manual to see what Sterling means by Limit Switch.

Hope this helps you to further troubleshoot the problem.

Apr 07, 2011 | Heating & Cooling

1 Answer

Green light flashes when i try to start my TFO 75 garage furnace

Looked at Sterling garage heaters in general. 3 blinks read pressure switch. You should have code chart on furnace door. Pressure switch symptoms are blocked vent or moisture in small hoses connected to pressure switch or bad pressure switch. If small hoses have sags take off one end and dump or both ends and blow through.

Jan 23, 2011 | Sterling RF75 Propane Gas Garage Heater

1 Answer

How do I set the heat at 75 with no fan mode. I don't want the fan to come on once the room reaches 75

Hi, there is no way that this can be done. The fan is controlled by several different parts for the furnace to run properly. If you are saying that the fan continues to run after it reaches its set point, this is normal if it only runs for about a minute and 1/2. This is to cool down the heat exchanger. If it continues to run all the time after reaching its 75 degree set-point, you have a fan relay that is sticking internally, or a high limit switch that has failed and depending on how old the unit is, it may be what is called a combination fan/limit control that has dirty or burned contacts which will keep the fan on. What I am trying to say, is when your unit reaches the temperature you want, the fan should only run a short time as the limit controls are there to shut it down from a setting on the fan control that is preset by the factory. If you can give me more information on your unit such as model, serial, name of unit, and if it is a gas fired central heat and air unit, or heat only, a heat-pump ect. would be of a big help to determine what controls you have on this unit that is keeping the fan on. Leave this info in the comment thread for my user name, and I will get back to you.
A/C, Heating, & Commercial Refrigeration Contractor

Jan 12, 2011 | Heating & Cooling

1 Answer

Furnace fires up and heats to desired heat setting and burner shuts down , but the main blower continues to run on.

its the fan control AFC not shutting off , it comes on at temp rise say 150f drops back to 130f with fan on , burner shuts off fan runs untill temp falls to 100f the fan shuts off in this case it keeps running

Nov 13, 2010 | Dayton Gas Furnace Heater

4 Answers

Thermostat seems to be working, furnace does not always turn on

Joss sounds like the anticipator setting on thermostat i would replace it with a digital it will be more actturat . The furnace has to go over temp setting to turn off

Jan 15, 2009 | Honeywell Electronic Programmable...

1 Answer

150000 1974 national gas forced air furnance does the fan come on the same time the gas comes on. ...

not familiar with that particular model but on virtually every type and style of furnace i have worked on in the last 21 years. the fan is delayed. usually the burner lights then 3 to 5 minutes later after the heat exchanger has gotten nice and hot the fan comes on and blows nice and hot air. on old furnaces there was and is a switch usually on the upper right side of the furnace bulkhead that has a spring like device that heats up and rotates till it makes a set of contacts that turn the fan on. if it gets to hot the set of contacts breaks the power to the gas valve and shuts down the burner. as the furnace cools down on shut off there is a third set of contacts that open to turn off the fan so you don't get a draft. sometimes the stat can be wired up wrong, and it will bring the fan on right away ,and air will be cool and drafty till furnace catches up.

Nov 12, 2008 | Heating & Cooling

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