My 2 stage gas furnace is nearly 23 yrs old, I put new filter in every month to 6 wks. Keep heat set 72 yr round . Had earlier yrs alot parts an blower motor put in. Not a one problem in at least 5-6 yrs. No rivets in bottom furnace a yr ago. That would indicate a heat exchanger fail. I was told. See no rivers from it lay on bottom furnace . Got appliance repair protection plan now an got free annual HVAC next week. Well not free as I pay for it every month . Anyone know on how u know heat exchanger crack ? My windows in house always fog up moisture alot an lately when furnace on but I think do that for many yrs . I hear if they find bad heat exchanger they shut ur gas off right now, I have CO2 detector upstairs

Put a carbon monoxide detector in your basement.

Turn on the fan only. Take a bbq lighter and put it in front of the burner tube, if the bbq lighter blows out or dances lots its cracked. There's lots of good videos on you tube about how to test it. And yes if they find it they will disable your furnace immediately.

There a cover on furnace . If take off. Safety switch is released an won't run..I guess find out . I would think there be other symptoms . I rember when they put new gasline in. A technician had go house an look at anything do with gas. He couldn't figure out there safety switch on front panel an kept screw around furnace. Has show him how lite water heater. He wasn't who is come out though . Furnace pretty pricey . There lot different furnaces can buy. Some cheaper but installation is the thing. I read it smell.like formaldehyde . If crack heat exchanger . The windows sometime fog at nite. Something do with dry out an inside not. All I know is I heard rivots on heat exchanger fall down an u see them if shot. No rivots lay around . Some tech was say my furnace last 30 or more yrs. If we're cracked, I have to see them myself

CO detector not CO2 big difference

Installing a furnace isn't rocket surgery. I replaced the gas furnace and central air unit in our home myself. I had a licensed HVAC person inspect my work after I installed it and it was good to go. Ordered my furnace from Alpine Air in Colorado. I think I paid about $2800 for furnace, A/C unit and all the parts to install, delivered to my door. About $10,000 less than a couple of HVAC companies wanted.

How many people have the equipment to braze the line set or vacuum the lines?

Make the door switch then start the furnace and watch for flame roll out,

You're right, I had the fella who checked my work do that part and charge the A/C. The bill from him was $160.

Beware of performing tasks requiring a license. If your house burns down, your homeowner policy may not pay. On the application that you signed, there is a question regarding HVAC, electrical, and plumbing done by a licensed contractor.

When I was in the insurance business, an applicant bragged during a telephone call by an underwriter about all the work he had done himself. His application for insurance was promptly denied.

Had another client that did some electrical work himself. House burned down and his wife was killed. The company cancelled his coverage on his renewal date, a few months before the fire.

Our windows used to get condensation on them. Turned out to be a mostly clogged chimney.

Exactly the reason I've never had nor intend to have homeowner's insurance. It's supposed to be homeowner, not insurancecompanyowner. If I can't fix the AC in my house, or heat my house with wood.... is it really even my house?

I'm a bit confused about all the comments about windows with condensation on them. Is having condensation on the inside of your windows in cold weather NOT normal??

So older furnaces are likely to have crack heat exchangers ? They shut it furnace down if so ?

A little moisture is one thing, but excess Condensation on your windows is not normal, unless the heated area’s windows are single pane. Condensation forms due to the products of combustion not ventilating properly. Cracked exchanger or blocked chimney are two causes. This moisture also is a sign of higher than normal CO levels which could be dangerous and/or lethal.

Do you have a mortgage? If we don't get insurance or let it lapse, the lein holder will put it on at our cost. Usually more than what we pay.

In my case yotetrapper the condensation wasn’t the typical you sometimes see, it was heavy at the bottom of the glass and not foggy, just drops of water. Hadn’t lived here long and just assumed that’s how this house was and I used to just wipe it up. One morning I noticed the furnace would turn off and on much quicker than normal. Short cycling I believe the furnace guy said. He found the clogged chimney and that was the issue. Then he told me to get a carbon monoxide detector in there somewhere close to the furnace. Also don’t get me started on homeowners insurance lol

Just see condensation on windows sometimes in morning. Later in day..nothing . I take the detecter down by furnace but probly most detectors don't go off, unless quite bad

Can't bad leaking windows have condensation too?

Actually, those detectors are very sensitive.