HVAC Repair and Advice Thread

[Clark Addison]

I figure with as many engineers as we have here, someone should be able to help me with my HVAC question.

Our upstairs system has an issue. When the inside tempreature hits the thermostat level, the A/C unit outside turns on, as it should, and then, 30 seconds or so later, the blower turns on, as it should.

Unfortunately, what often happens if it stays on for more than a few hours is that the blower will stop blowing, but the A/C unit will stay on. If you turn it off, leave it off for just a few minutes, then turn it back on, the blower still will not work. If you leave it off for a while, however (30-60 minutes), it will usually start working again.

Is there any chance that this is a problem with the thermostat, and if I go and get a new thermostat everything will start working correctly? That would be nice, as I know how to do that myself.

The entire system is about 14 years old, so I am a little nervous that it is running up against it's expected life.

[Uncle Ted]

I figure with as many engineers as we have here, someone should be able to help me with my HVAC question.

Our upstairs system has an issue. When the inside tempreature hits the thermostat level, the A/C unit outside turns on, as it should, and then, 30 seconds or so later, the blower turns on, as it should.

Unfortunately, what often happens if it stays on for more than a few hours is that the blower will stop blowing, but the A/C unit will stay on. If you turn it off, leave it off for just a few minutes, then turn it back on, the blower still will not work. If you leave it off for a while, however (30-60 minutes), it will usually start working again.

Is there any chance that this is a problem with the thermostat, and if I go and get a new thermostat everything will start working correctly? That would be nice, as I know how to do that myself.

The entire system is about 14 years old, so I am a little nervous that it is running up against it's expected life.

It could be your blower motor is overheating and the overheat protection is kicking it off. This would explain why if you leave it off for a while it will start working again.

If you do end up replacing the thermostat consider getting one of these...

http://www.radiothermostat.com/filtrete/

They sell them at home depot for about $100. I got them on sale for $75.

The cool thing about these is that you can control them using your iPhone from anywhere. Like when you leave for a trip and can't remember if you left the heat turned up or not. Also, there is a free web service that you can use to program it. Note that these thermostats do require that you have a 24v DC power feed coming down from your A/C unit and a wifi connection.

[thesaint258]

Our vents are located in the ceiling, so I had to take the registers down to paint the ceiling. When I did, I found that they were barely screwed into anything because the builder wasn't very precise when cutting the holes in the sheetrock for the vents. Now, I have several vents that have one side where the screw can go in, but empty space over the other screw. Any ideas on how to put those registers up?

[creekster]

Our vents are located in the ceiling, so I had to take the registers down to paint the ceiling. When I did, I found that they were barely screwed into anything because the builder wasn't very precise when cutting the holes in the sheetrock for the vents. Now, I have several vents that have one side where the screw can go in, but empty space over the other screw. Any ideas on how to put those registers up?

TO me it depends on the condition of the sheetrock and how much room you have between the hole and the edge of the register opening. In general, you could use a molly bolt, a toggle bolt or some other similar type of anchor. But if the sheet rock is not in good enough shape to be able to support that sort of anchor, or if the hole will be so close to the edge that the anchor would ruin the hole, they may not work.

The duct work should terminate at the register opening with a flange. I would try to locate the screw through that flange, as that would not depend on the sheet rock at all.

[hanifnoor]

Our upstairs system has an issue. When the inside tempreature hits the thermostat level, the A/C unit outside turns on, as it should, and then

[Donuthole]

Our upstairs system has an issue. When the inside tempreature hits the thermostat level, the A/C unit outside turns on, as it should, and then

the suspense is killing me.

[creekster]

...and then the Internet goes out.

[clackamascoug]

He got a little too excited on his first post, and it ended rather abruptly.

It happens.

[Scott R Nelson]

Why is it that the air conditioner only goes out on 100 degree days and the heat only goes out on the 10 degree days?

Woke up this morning to a bit cooler than usual, 64 degrees inside. Sometime in the night the furnace decided to stop working. I already checked all of the easy stuff like the thermostats, circuit breakers, etc. Have a call in to Capital City Heating and Air (yeah, that's how they spell it). They'll send somebody by sometime this morning.

I should be thankful that it's something that won't take long to fix. My son, who lives in Truckee, had the power out for multiple days with only their fireplace for heat and way colder temperatures than here.

It seemed like a good time to turn on the self cleaning oven, since that generates a bit of heat. Our "fireplace" is one of those with a light switch to turn on and off. The gas heat for that doesn't heat much more than a few feet out.

Just griping here, it's not really a big deal, just a minor inconvenience.

[Bo Diddley]

Why is it that the air conditioner only goes out on 100 degree days and the heat only goes out on the 10 degree days?

Woke up this morning to a bit cooler than usual, 64 degrees inside. Sometime in the night the furnace decided to stop working. I already checked all of the easy stuff like the thermostats, circuit breakers, etc. Have a call in to Capital City Heating and Air (yeah, that's how they spell it). They'll send somebody by sometime this morning.

I should be thankful that it's something that won't take long to fix. My son, who lives in Truckee, had the power out for multiple days with only their fireplace for heat and way colder temperatures than here.

It seemed like a good time to turn on the self cleaning oven, since that generates a bit of heat. Our "fireplace" is one of those with a light switch to turn on and off. The gas heat for that doesn't heat much more than a few feet out.

Just griping here, it's not really a big deal, just a minor inconvenience.

That's funny, our heat went out yesterday. The missus told me it wasn't working right and the thermostat was showing 63. I couldn't tell because she keeps it cold in the house. I guess I can't tell the difference between 63 and 70.

The furnace was throwing an error code, and I think the ac/heat pump outside was actually putting out some heat, but not eniugh and the furnace wouldn't kick on. I'm well overdue to put a new filter in, so I vacuumed it out and turned it all on again. The furnace worked after that,, so we're still in business.

[Scott R Nelson]

I find it interesting that after the guy showed up to fix things, after fiddling with a few things in the same way I had, the furnace started to run. That maybe could have gotten me through a few more weeks, maybe.

I had him do a full service anyway. It looked to me like the cause of the issue was some sort of heat sensor that is an L-shaped wire about the diameter of a wire coat hanger that sits in the flame. He had to take it out and use some emery cloth to clean the flame residue off of it and make it shiny again. If there is a next time while I can still remember this, I'll open it up and clean that part before calling anybody. I should probably do that every couple of years anyway.

I appreciate having a warm house, even more now.

I also learned that a self cleaning oven does a credible job of heating a house for the three hours or so that it takes to do it's thing.

[Pelado]

Why is it that the air conditioner only goes out on 100 degree days and the heat only goes out on the 10 degree days?

Woke up this morning to a bit cooler than usual, 64 degrees inside. Sometime in the night the furnace decided to stop working. I already checked all of the easy stuff like the thermostats, circuit breakers, etc. Have a call in to Capital City Heating and Air (yeah, that's how they spell it). They'll send somebody by sometime this morning.

I should be thankful that it's something that won't take long to fix. My son, who lives in Truckee, had the power out for multiple days with only their fireplace for heat and way colder temperatures than here.

It seemed like a good time to turn on the self cleaning oven, since that generates a bit of heat. Our "fireplace" is one of those with a light switch to turn on and off. The gas heat for that doesn't heat much more than a few feet out.

Just griping here, it's not really a big deal, just a minor inconvenience.

Capital City is who I've used for things - they were much less expensive for a new furnace in my old rental than the other quote I got. They've always seemed to do a good job.

I got a call from my wife a few weeks ago saying that the heat was out. I went home expecting that she had messed something up with the thermostat, but it seemed to be set properly. The fan would kick on, but no heat would come out.

So I started poking around on the furnace, removing a couple of panels and seeing that the fire would ignite but then shut off just as the fan was turning on. I did a Google search that indicated that the heat sensor may have needed cleaning. So I removed what looked like it could be the sensor and cleaned it as best I could and then replaced it. I also cleaned off some areas that looked a little corroded. After I put everything back together, I realized that the part I had removed and cleaned was the piezo-style spark system, and not the heat sensor. And when testing it, I found that now the fire wouldn't start at all (even though I did still see it sparking).

I eventually identified what I think was the actual heat sensor, but I don't think I was able to remove and clean it. I kept testing it and finally got the flame to ignite and stay on. Had it gone much longer, I was preparing myself to call Capital City in spite of it being after hours and/or a weekend.

Haven't had any problems since then, but I probably should get it scheduled for a full service.

[chrisrenrut]

I find it interesting that after the guy showed up to fix things, after fiddling with a few things in the same way I had, the furnace started to run. That maybe could have gotten me through a few more weeks, maybe.

I had him do a full service anyway. It looked to me like the cause of the issue was some sort of heat sensor that is an L-shaped wire about the diameter of a wire coat hanger that sits in the flame. He had to take it out and use some emery cloth to clean the flame residue off of it and make it shiny again. If there is a next time while I can still remember this, I'll open it up and clean that part before calling anybody. I should probably do that every couple of years anyway.

I appreciate having a warm house, even more now.

I also learned that a self cleaning oven does a credible job of heating a house for the three hours or so that it takes to do it's thing.

Flame sensor. I has to clean that at least once a year on our old furnace.

we replaced our furnace almost 2 years ago. It seems much more complicated, I’m. It sure I’ll be able to do any self service on this one.

[Pelado]

Capital City is who I've used for things - they were much less expensive for a new furnace in my old rental than the other quote I got. They've always seemed to do a good job.

I got a call from my wife a few weeks ago saying that the heat was out. I went home expecting that she had messed something up with the thermostat, but it seemed to be set properly. The fan would kick on, but no heat would come out.

So I started poking around on the furnace, removing a couple of panels and seeing that the fire would ignite but then shut off just as the fan was turning on. I did a Google search that indicated that the heat sensor may have needed cleaning. So I removed what looked like it could be the sensor and cleaned it as best I could and then replaced it. I also cleaned off some areas that looked a little corroded. After I put everything back together, I realized that the part I had removed and cleaned was the piezo-style spark system, and not the heat sensor. And when testing it, I found that now the fire wouldn't start at all (even though I did still see it sparking).

I eventually identified what I think was the actual heat sensor, but I don't think I was able to remove and clean it. I kept testing it and finally got the flame to ignite and stay on. Had it gone much longer, I was preparing myself to call Capital City in spite of it being after hours and/or a weekend.

Haven't had any problems since then, but I probably should get it scheduled for a full service.

My wife and I were out of town earlier this week. My sister-in-law came and stayed at our place to protect against the kids killing each other.

Upon our return, she apologized for messing up the thermostat. She said it was cold in the house the previous night and so she tried to adjust the thermostat to be a few degrees warmer, but that she must have accidentally turned it to cool since it dropped a few degrees.

The thermostat was actually fine, and I found that the furnace was having the same issue as a few weeks before. After fiddling with a few things, I called Capital City and the tech talked me through how to remove and clean the flame sensor. With my son's help, we removed it, cleaned it, and replaced it. And the furnace started working just fine.

But that working state didn't last. I tried a few other things that night, including another round of cleaning the flame sensor, but nothing worked. I got the gas fireplace fired up for the first time since before we moved into the house 15+ years ago. It was kind of entertaining to watch the significant quantity of dust go up in flames. But I'm going to have to agree with Scott - the fireplace did not produce nearly as much heat in the house as I was hoping for.

I called Capital City again and the technician came by that morning. He identified a few issues with the furnace, but the proximate cause of the problem seemed to be that the control board was faulty. He didn't have a replacement control board on hand. And there were some additional parts that could have also been an issue. And, since the furnace was 23+ years old, it didn't seem wise to put a lot of money into repairing it.

So I had them come by that evening and install a new furnace. The old one had been a Rheem 90% efficient model. The new one, a Goodman 96% efficient model, was a lot less expensive than I was expecting - about $3,500. I was expecting it to cost much more since the less efficient Goodman I had them put into my rental several years back had run $6,000 (if I remember correctly).

So now we have as much warmth as we need.

[Bo Diddley]

Awesome.