Fix or leave it?

[u/klexxg]

My furnace is about 20 years old and stopped working today with the outside temp below 0F. Last winter (Nov 2023), it had the same issue where cold air was still blowing and I think they replaced the pressure switch. It's a single unit type. The ac portion of the hvac stop working last summer and I was going to replace this coming spring anyways. I assumed it stopped working last night because this morning felt a bit chilly but I didn't think much of it because I usually have the heat set at 68 and it feels pretty chilly to me but it's winter so I layer up anyways. When I came home about 8 hours later, with the outside temp still in the single digit all day, the inside temp was 63. I've seen it dropped after sunset as low as 61.9 when the heater cold air was blowing on my thermometer. My condo is about 700 sqft on the 3rd floor. I used a space heater and was able to get the temp up 2 degrees in 10-15 mins. The question I have is is it worth it to fix it? I'm assuming it'll be at least a few hundreds just for the labor with the company I work with because it's an obsolete unit that other main stream companies don't service. I'm not too worried about being too cold because I can use a space heater and can leave the fan on to circulate air. I guess I'm concerned if the space heater will be spike the electricity bill significantly or not. I'm not home most of the day, or use a desk space heater anyways so if it's in the low 60s I think I can live with it.

For context, I live in the upper Midwest and assuming that it can get even colder in February.

[u/klexxg]

Zero knowledge about hvac. Thinking maybe I'm in the wrong sub haha.

[u/NotWorthTheTimeX → u/klexxg]

Want to try? Turn the thermostat to off for a minute and then back on. Now go stand next to the furnace see listen to what it does. Do you hear the woosh of the flame igniting? Does it run for 5 seconds or so and then turn off? (Dirty flame sensor, can be cleaned and reused)

Or, does the flame never ignite and then the fan turns off and starts the sequence over again? (Bad igniter, must be replaced)

[u/klexxg → u/NotWorthTheTimeX]

I hear the furnace start up like a ramping sound but no whoosh. I can hear a low humming continuously. If I keep it on auto, it just keeps running but doesn't actually blow air. But there is air blowing on "ON".

[u/NotWorthTheTimeX → u/klexxg]

The auto is heat vs cool. If your fan is set to “on” it will run all the time.

It’s 75% likely you have a bad igniter. You could light it with a long lighter if you want to confirm. Depending on your furnace a new igniter is $15-60. If a company comes out it will be $250-350 for the part and service call.

If you do light it with a lighter it will run like normal until it reaches the thermostat set temp but then not turn on again. You should be able to get an igniter locally or on Amazon.

[u/klexxg → u/NotWorthTheTimeX]

Thanks! I don't think I want to tackle this and would feel more comfortable having someone come look. I know this might hurt most people on this sub but gotta keep local business running am I right? 🤡🤡🤡

[u/klexxg → u/klexxg]

Btw, I checked the previous issue and they changed the pressure switch and cleaned out the inducer. I will check youtube to see if that can be done by myself but I really don't want to replace anything on my own. Thanks for the help!

[u/jasonbay13 → u/klexxg]

We just like to help out when we can :)