Help! Heater comes on every few minutes

Ben2019

Hi everyone! New homeowner here. I have been having trouble with my heater. It is from 2013. Brand is Trane. A couple weeks ago in the middle of the night there was a knocking noise coming from the bathroom vent whenever the heater was on. The noise stopped within a couple hours and everything seemed fine. A few days later I noticed the heater had been constantly on so had someone over to look at it. He ended up changing the filter which was nasty dusty! Thought that was the end of my problem but the same night the blower fan stayed on pretty much the entire night. I finally got up and kind of messed with the thermostat(set it one degree lower) and it would stop for a while before it started coming on again. Had another person come and he reset the thermostat.

So this morning the temperature had dropped to 31. Kind of chilly I guess. The heater is set for 69. And I’ve noticed that it has been on every 10 minutes. I also noticed that when it comes on the thermostat says 69 on both the set and the inside temp. I guess it’s trying to keep 69 but it would be on for 10 minutes or so...

So does this sound like my heater is somehow out of order? Or is it normal? I just feel like it’s been on an awful lot. Kind of scared of our bill this month...

HVACNUT

From what you've written, it seems as if the furnace burner circuit is opening on high limit. When it does, the burners turn off and the fan comes on automatically to cool the heat exchanger.
Once the furnace temp drops, the burners will start again. And round and round she goes.

The plugged air filter will definitely contribute to that. But now its clean so there are other issues.
How often do you replace the air filter and is it a flimsy 1 inch or a decent media filter?

Did any of the techs check for debris caked on the actual fan blades?

A/C evaporator coil on the supply, above the furnace?
Could also be clogged.

How is the airflow out of the vents? Same as usual or not as strong?

The tech should take a TD (temp diff) test at the furnace, not the vents. Temperatures rise must be within manufactures specs. It's written on the inside the burner or blower compartment with model, serial and other info.

Let us know.

Edit:
Just reread your post. New owner.
If the tech seems reliable and not a salesman, ask about your concerns if any.
High efficiency air filter.
Steam humidifier.
UV light or ionization light.
A/C if not equipped.

Ben2019

Hi HvACNUT! I really appreciate your message. Neither of the guys checked any of the things you mentioned.

This being the coldest day (windy too) in a while I’m not exactly sure what to make out of it. So I guess it is definitely running too much you’d say? It comes on for around 10 minutes and stops for 10 minutes to maintain 69 with the outside temp being 31.

Jamie Hall

That may be normal for forced air. It is common for the thermostat to set for that kind of interval. If it is holding temperature OK, that's something anyway.

No harm to checking the stuff @HVACNUT mentioned, though.

Ben2019

@Jamie Hall hi Jamie thanks for the info. When you said it’s normal for thermostat to set for that kind of interval did you mean it is probably set to kick in at that interval when the temperature drops to a certain degree? Because it was definitely not doing this yesterday. Sorry this is probably a pretty “duh” question but I really don’t know much about heaters at all:(

Jamie Hall

Forced air heat is commonly set so that there it shoots for six heating cycles per hour. The idea is to maintain as even a temperature in the air in the space as possible. The cycling will depend somewhat on outside air temperature.

Ben2019

@Jamie Hall I see. Guess I’ll wait till it gets a little warmer and see what happens. It’s reassuring enough to know that it DOES turn off after a few minutes whereas a couple days ago it was running constantly for like 30 minutes. Thanks!

HVACNUT

Apologies. I misread. I thought the space wasn't maintaining the 69° set point.
10 on, 10 off isn't too bad.
Could be oversized though.

What model Trane?
Over 90% efficiency?
What model thermostat and is it configured correctly?

Ben2019

@HVACNUT thanks for updating! Any idea what the noise might be about? It never came back though. Just those couple hours.

Jon_blaney

Ductwork flexing with changing pressure? Plugged system with bad filter? Was it a constant noise or a one-off?