#AskDerekCole Epsiode 46
28 Jan 2026 · 10 min
Derek Cole answers questions about a furnace that hums but won't run, thermostat delays after power loss, and why your AC efficiency drops. A dirty filter loses 21% efficiency at just 1/20 inch of buildup.
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You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, this is Derrick Cole. Welcome to episode 46 of the Ask Derrick Cole show. Answering your home energy and heating and air questions.
My furnace will start up and when it gets ready to start blowing the warm air, it turns off and doesn't blow at all. It makes a humming sound. So, you know, there is electricity to the unit. There is an off switch that I have to flip a few times and then the blower starts. This happens several times. It has an electric pilot and runs on propane.
Yeah. So you want to get that checked out because that sounds like an issue. A few things could be happening. It sounds, first thing sounds like you mentioned the pilot. So you probably have a good idea. Then it's like the flames actually lighting. So you could have. The pilot could be dirty, it might need cleaning, or could not be working at all. So you need to check that out and make sure that's happening. It does need maintenance. Now with those. Today's furnaces have glow pilots or I mean, there's not like a flame pilot anymore. It glows, gets really hot and then when it gets red, dead light, you know, ignites the gas. So you're good to go on that one. But what happens? Those get cracked. Those, they might need sanding. They might need a little maintenance as far as cleaning. And that sounds like it could be an issue as well. Or if it is lighting and then turning right off, you could be having a pressure, gas pressure problem. So when the pressure switches might be turn it back off for your safety. So a few different things could be happening with that. You need to get it checked out by a professional for sure because it does sound like you're having some issues.
All right.
Does that make sense? That makes sense. Periscope.
Okay.
Is your thing, is your mic on?
Yeah.
Okay.
Okay. Why did my unit tell me to wait when I manually lowered the thermostat and then took five minutes to turn on?
The last time I checked, I don't think there's like a wait flashing light that happens on thermostat. So I'm not really sure. No, but what happens is between the time your unit turns on and gets the call, there's usually a delay depending on the type of unit if there's a power outage. But the compressor has a built in delay in it. That way it don't start and then stop. It's for a safety protection. So you probably waited about five minutes because that compressor had the signal to Call to come on and then it was in a stage of coming on. So that was probably why that was. Now, when the power goes off, you're gonna have that five minute delay as well. So if your power goes off and then comes back on, you're like, where's the cool air out? Well, it's making sure the power is gonna stay on. Then it turns it back on because it doesn't want to turn on and then turn off. That's not good for the compressor, it's not good for the system. So you don't have that built in time delay, as they call it. See little air quotes. Time delay is built into your system, but it supports the components and for your protection because they don't want to damage any of the components.
How can you tell if your unit is still operating efficiently?
The power bill is a good way to tell if it's operating efficiently. But I would get it serviced twice a year because again, I think I've said it before, but if you go to epa.gov look it up, 1/20 of an inch of dirt, it calls up to a 21% inefficiency in your unit. So if you just bought a 13 seer base product, but you don't clean it for the next two years, it's not a 13 sear unit anymore. So it's not as efficient as it could be. So these units cost quite a bit of money. It's quite a bit of investment. So you want to keep protecting your investment by having it serviced and maintained and cleaned. Because the systems of today are not like the systems 25, 30 years ago that could withstand that kind of buildup. They had thick copper. Efficiency was not a big concern 25, 30 years ago. You can see it in the home building. I mean, the house is built 30 years ago versus the house. Houses built today. The ones today are a lot tighter, more energy efficient. The units are the same way. So any little bit of dirt, dust, debris can affect that efficiency. But if you see your power bill start creeping up, that's kind of a good indication as well as just walk on that and look at your unit. I mean, if you got grass clippings all on the coil and everything, it's not operating efficiently because it's having to overcome that dirt and debris to transfer the heat. And that is costing you more money.
Do you want to do the last one? Do you want to do it for. You're only at five minutes on the sixth one.
Yeah.
Slide your cup back.
Is it in the chat?
Nope. It was Just like the clip. Okay, this was my question. What did that metal.
We got a homemade question vent in.
My house do and should I use it? Remember the one I was talking about in the ceiling? Big old metal thing. When you turn it on, it goes. I asked you.
Yeah. So.
What does that metal fan or vent in my house do and should I use it?
She has bought an older home. Correct. Just renting it or renting an older home. Okay. So what that is, is in the old days, black and white, no color. In the old days, you would open a window or doors and. And you would turn that switch on and it would bring air into the home. So it would make it more. I don't want to say windy, but what's the term looking for windy in the house?
It, like, creates a draft.
Almost draft. Yes. It is creating a draft in your house so you can cool down. Because in those days, a lot of people didn't use air conditioning. And it kind of goes back to my first point about older homes versus new homes, because older homes are kind of built for that, you know, innate kind of breeze or draftiness. Because again, they were not really concerned about being energy efficient, as today's houses are less efficient. Today's houses are not going to have that. If you open a window, good luck. Because the breeze is not going to go through the house. It's just not going to work the same way it did 30 years ago. So that is why you have that. They also have those little switches for electric heat in the. In the older homes. If you want to talk about something to really jack up your light bill, turn that baby on. I would. Unless you want to. Unless you want to go back to colonial times. Wear the outfits, play dress up. You probably don't want to turn on.
Plus, it's very loud.
Yeah. Plus this is southeastern North Carolina. I mean, you really want humid, wet air coming through your home. No, you want the air conditioned, which is the conditioned. Air conditioned air. Dehumidified, more comfortable. So that technology is not really used anymore. That makes sense. Yeah. All right. We're black and white. Yeah. You know, if you want to dress up and do like a Colonial Day.
Like a little pilgrim dancing.
Yeah, do a little colonial day. I mean, you can turn it on. And actually, back then, they probably didn't have electricity. So if you want to be, like, really authentic, just open the windows and turn lights off and, you know, go for it. Did they have houses back then?
I'm pretty sure they did. Why are you asking me?
I don't know. So if you really want to go the extreme. I mean, stones and mud, I think. I don't know. Yeah, yeah. Go camping.
Yeah.
You know, I didn't go camping as a kid because my parents loved me. That's why I didn't go camping. I'm just kidding. For you guys that are there, I like camping. That's fine. That's your deal. That's your deal. But they asked me one day, do you go camping? I'm like, does it look like I go camping? No, not on purpose.
Breaking down outside.
All right, so this is. This has been a weird one, but episode 46 in the books. Keep asking your questions, hashtag askdericole, and we'll get him on the show.
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