I can kinda agree with your Dad but it is not just furnaces but all HVAC equipment. Now before we go on with this discussion I need to make a clarification.

What I am talking about is the difference between fixed and repaired, and maybe those aren't even the right words but for now will go with them.

What I am talking about is say a limit goes bad. You can replace the limit and it works so it is fixed. But wait a minute a limit is a safety control, it should never operate, so if it goes bad there is more wrong than just the limit.

This is where repaired comes in. If you find the cause of the failure and fix that now it is repaired. In the case of the limit increase air flow to proper levels and the new limit may last the life of the furnace. Leave it as is and it may fail again in 5 years of less.

So, how many are fixed and how many are repaired?

 

Everything within reason can be repaired or replaced. No furnace can run forever w/o something going wrong though some do really well.
Some flat rate companies might charge enough that you think replacing would be cheaper. But not if they do it for sure.

You could ask if that advice also applies to cars.

 

It's rare in my area to ever replace a gas furnace unless the AC is getting replaced and we put a new furnace in with it. The only part I have never replaced is a heat exchanger and I will likely never replace a heat exchanger unless I move to a northern climate where they actually go bad. Now this year was a very abnormal year I replaced a furnace because the crappy smart valve went out but most of the time we'd even replace a smart valve.

 

By the way expedite it are you getting any closer to getting back into the trade?

 

Not really.

 

Oversize units cause short cycling resulting in cracked heat exchangers & corrosion failure.

Low air flow results in high dt causing cracked heat exchangers.

High limits, flame sensors, gas valves, inducer wheels….
Package units more likely to have heat exchangers replaced.

 

I have replaced everything on a furnace other then the cabinet.

Only replace heat exchangers under recall/warranty.

Replace entire furnace if old exchanger is rusted or plugged.

But like R600 said if new AC then new furnace because of larger coil requirements.

Used to change outside unit only and use old coil, back in the days of R-22.
It was always a mis-match and most likely not very efficient, but people just wanted to be cool. Short 2-3 month cooling season here.

Did you figure out the "Ohms" question you had in your other posting?

 

I had a Trane XE90 for 23 years. Furnace was still good to go but the AC side crapped the bed and replaced everything.

In 23 years of use the parts I replaced on my Trane XE was a gas solenoid valve ( sticky ) , flame sensor that after several cleanings died , gas ignitor.
Pretty solid furnace.

 

Yes Sir, I've checked the problem with your furnace. It's a broken knuten valve.
The valve costs $2 but we are replacing the furnace instead. The charge is $6400. Will that be check, cash, or credit card?

 

I’d say there is only 4 issues I’d recommend furnace replacement on.

Variable speed inducer.
Variable speed blower.
Failed heat exchanger.

Those are only relevant to age. I’m not including the insanely old equipment, that has unavailable parts.

Failed or improperly vented chimney, changing to a direct vent.


Maybe, maybe, a board, depending on how expensive it is.

 

A heat exchanger is the only issue that I recommend replacement on. After that it is a matter of looking at the cost of the repair and the condition of the unit, then lay it at the customers feet.

 

This is how we do it. Not everyone can afford a replacement and need to wait. I still make good money on the repair, customer trusts me more because i didn’t just come in and say replacement is the only option and I probably get their replacement business in 2 years.

I like using the old car analogy; It’s kinda like an old car. We can try to keep it running but you need to be prepared for more surprise breakdowns and lower efficiency. Just like an old car, It probably doesn’t have the same power and gas mileage as it did when it was new but we may get another year or 2 out of it.

 

I fix it if it can be fixed... and it's in line with what the customer wants and can afford. the repair needs to be safe and OEM/trade approved.

ah the good old days of Pulse pineapple exchanger replacements...

 

Ditto

And...my favorite residential furnace of all time. You could diagnose it by listening to it. The Pulse was a beast!

 

To keep it simple a gas furnace is only replaced when they can afford it...there are tv ads in my area showing free furnace with every new A/C system replacement...(ironically it’s a packaged air handler that the new evap coil is already in)

 

I've replaced almost everything, just depends on the job, the cost, the customer. I have replaced heat exchangers on package units that we thought the cost was economical, ie $900 for exh and $4K for package unit in a place that was hard to access and there has never been any problems with the a/c, everything looked in really good shape, so I let the church make the decision, after giving them proper info. Have only replaced one hx on a standard furnace in the last several years, it was a commercial building, and it was a fairly new unit and the furnace was in excellent shape, and they decided it was what they wanted to do.

 

Unfortunately your father is right about part of it - gas furnaces are replaced instead of being repaired. With the exceptions of a few parts already listed (variable speed inducers, ECM motors,heat exchangers,etc.) it's almost always cheaper to repair a furnace than it is to replace one. It really just depends on the culture of the company doing the pricing of the repair and the budget of the person getting the repair done. Some people want the peace of mind of a new shiny warranty and some people are trying to get by and still pay the grocery bill after they get the furnace fixed.

 

pressure switch