Burner clicking on and off rapidly when reaching restart temp.

How many degrees before it reaches desired temp, does it shut off? A thermostat is designed to shut the furnace off a couple/ few degrees before it reaches set temp. It has what is called a heat anticipater, which shuts the burner down, and lets the blower use the remaining heat from the heat exchanger to bring it up to desired temp making it more efficient. If it is more than a few degrees, replace the thermostat. You can jump out the red and white wires to confirm the faulty thermostat. If by doing this, the furnace never shuts down, until you separate the red and white wires. That confirms a faulty thermostat. Hope this helps someone.

It sounds to me like your thermostat may be bad. I would check power incoming to t-stat then turn temp. setting up and down to see if it is switching on and off. If not then replace. If it does then I would check all wiring to gas valve and if power is shutting off to valve but burner continues then replace gas valve. Thank you.

No I do not believe it is your thermocouple, as that only detects heat from the pilot light and permits the gas valve to open and have main flame ignition. I would be looking at thermostat placement, and safety limits built in to the heater. Making sure that the thermostat is not getting a straight on blast of hot air from the heater is my first guess. Try jumping out the thermostat by first removing the thermostat from it's housing and placing a jumper between the red and white wires as they are usually the control for heat. If your heater stays running it is the thermostat. If not you now have to trouble shoot all safety limits one at a time with a volt ohm meter and run continuity tests the limits should read closed except for the fan high limit it should read open until the temperature of the heat exchanger reaches it's set temperature. Remember to power down your unit when trouble shooting please.

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

Hi blow heater out with air line flame sensor could be dirty check out pressure switch jump this out see if it lights

This is a good application of this type of heater. There are many things to consider as you size the heater though. Insulation, 1,2,3-car garage, insulated garage door, average ambient temp. etc. In most cases of garage heaters, they are used to temper the air from cold to a workable temperature. If this is the case, I'm sure this would take care of most applications of garage heating.

That's the fan switch. It's a thermostat that controls the fan coming on and off, it's probably failed and needs to be replaced. You can see it if you take the front off the furnace, the wires come off it and go to the fan motor.

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These heaters are the same as the marley heater, the element never gets red hot. the unit is set up so the fan kicks on after the element has heated to a certain temp and turns off after the element has cooled. It is common for these heater fans to cycle on and off quite often untill the air temp reaches about 55 degrees and then will operate normaly. If the fan still cycles too often you may have to replace the fan control and high limit switch. These are not very expensive and easy to replace yourself. they arte usualy attached to the back of the element with clips. The luke warm air is what these units put out. I have an equivelent to the dayton G73 and it heats a 24' X 30' garrage all winter in central Minnesota.

The sensor for the thermostat is probably going bad or has bad connections. It is (or thinks it is) heating up fast and therefore shuts of the heater.