Furnace replacement, what would you do?
 

I have a Trane VX90 furnace in one end of my house. It is at least 16 years old, maybe more. The control board is apparently failing. The inducer motor runs constantly, for one thing. Also, the igniter and gas won't come on until I shut the power off to the furnace for 30 seconds and turn it back on. ie, thermostat set at 68 degrees, room temp is 64, the inducer motor is running, but no gas and no ignition. Turn the power off, then on, the igniter lights, gas comes on, room heats up to 68. Then the thermostat turns the system off. The inducer motor stays on and will run for hours until I go down and turn the power off and on. Repeat every few hours.
HVAC guy says he can replace the board for $500, but recommends a new furnace. Fine. But the new furnaces are not compatible with old AC system, R-22 is going away, etc so he recommends replacing the whole thing. It COULD cost as much $10k depending on the furnace and AC I choose. Ouch!
I'm torn. $500 to repair an old system or $6,000 to $10,000 for a new system? What would you do?

I'd gamble the $500 and see if that fixes it for awhile.

My last Trane lasted 25 years...called my trustworthy HVAC guy....new Rheem ;).

No way will it last as long...new Tranes probably won't either :(. Shop around....mine was around 4500....others would have easily been double that. I've had Rheems in two of my rentals for years. You will pay whatever "they" think you will...hide yer Porch ;)

Not much good money after bad, especially if the fix lasts a while. I'd suggest a second opinion from a well regarded HVAC guy.

Leave the A/C, replace the furnace. The new furnace is absolutely compatible with the old system. I'll shoot you my phone number if you'd like to discuss. I think you're being sold a line of bs. I just installed a 95% efficient single stage furnace with my parents 24 year old heat pump system. I don't do installs for people other than my immediate family anymore or I'd hook you up. It's normally about a five or six hour swap.

Did the HVAC guy provide you the part number for the control board ? Or can you see the part number on the existing board ? I ask because generally you can purchase one online for much less than what is quoted . Our previous house had an issue that I diagnosed to a faulty control board , I was able to purchase online for less than 200.00 . I pulled one wire/connector at a time from old and transferred to new . Worked like a champ . This of course assumes that the control board is the only issue .

My Trane was a Nat. gas/AC unit...self-contained, completely outside...fwiw.

For your inducer fan issue, it's possible if someone changed the thermostat that it has a power scavenging feature that uses 24 volts from the furnace to power the back light or memory of the thermostat. I have a White Rogers with that feature. It is possible for this feature to cause the inducer fan to run constantly. Don't know when the problem started but might be worth a look.
When you turn the power off and then back on you're performing a "hard reset" of the circuit board. This hard reset clears the codes that prevent the furnace from lighting. Typically there is a light that will flash a code that tells you why the system is locked out.

Type your model number for the furnace into a search bar and include "circuit board" and you'll probably find your board for much less than the tech quoted. You can figure the cost is about half of the quoted price.

Well they don't call it the heating and stealing industry for nothing....

Yes, I looked it up. On this model, the kit involves a new board, new igniter, and a wiring harness. $495. I read the HVAC forum that the new igniter is a different material, the new board only supports the different igniter. :rolleyes:
The single speed version of this model is $195 new, with rebuilds available for less than $100. :(
I'm getting the sense that I'm effed every way I look.

Is your furnace a 2 stage heat with a DC drive blower?

I'm with craigster replace the board first. I have had two different heaters have the board fail. The AC people want the mark up on the new unit. They make more oney.

How long ago did you buy that house? Did it come with a home warranty?

Thanks. You might be getting a PM. He's coming out tomorrow to show me the furnace options. The physical size of the new Trane furnaces is the issue.
There might be a furnace of a different brand/different specs that is physically a direct replacement for this old one. We'll see.

I'd look up the board that is in your furnace. You might find a NOS board rather than the updated board that requires the newer HSI.
Also, I'd like you to clarify one thing, you say the inducer fan is running. Just want to make sure we're talking about the same thing here. The inducer fan is the small purge fan that typically runs prior to the furnace igniting. Is this the fan that is running constantly?

Ha! Yes! I have a home warranty, it's with Old Republic. I called them once. The lowest bidder for the job came from 50 miles away, took him 10 days to finally show up. I paid Old Republic the $100 per visit fee so they could tell me "we don't cover that." I'll never call the worthless SOBs again.

Yes, it's running and it makes a clicking sound when it starts up. This just started happening last week, when I began using the wood stove. It worked fine all last winter.

Normally it's the height as the newer units are shorter than the old ones. When I got into HVAC the "shorty 40's" were the small size units. The newer furnaces are only about 36" tall. Don't let that scare you. If you want to, give me the dimensions and I can tell you what will match. Very few today will match height but the cabinets are either 17.5 or 21 wide. The height only matters when it comes to what has to be done to connect the old return air duct to the shorter furnace.

You're in this place for the long haul...

Replace it now or replace it in a few years...imo.

But I don't know squat about this stuff :).

Take a look at the burners and other parts and see if they would likely last for a few more years. If so, fix what's broken and don't look back.

If you buy a new furnace and it's physical size is different then the air-conditioning plenum, have the contractor make a short transition piece to get from one size to the other and don't look back.