Repair or replace furnace / air handler?

[soupcxan]

Live in Houston. Bought a house with a 20 year old furnace. The system has an 5 ton 8 year old AC system. The control board on the furnace just died. We only use the furnace a few months out of the year, but the furnace contains the A/C fan, so no furnace = no A/C which is death in Houston.

The AC guys replaced the board for $500. But, they said at 20 years, its only a matter of time before something else goes on the furnace. The fan motor would be another $500. They'll credit the $500 toward the cost of a new furnace, so I could get a new Trane for $2500.

Would you stick with the $500 repair and try to get a few more years out of a 20 year furnace, and maybe replace the entire system at once, or pay $2500 extra now for a new furnace and replace the AC system whenever it's due?

 

[heeyy_joe]

In Houston? Stick with the repair.

 

[Mulligan]

I will probably face the same staggered problem... A/C unit went out after 10 years damaged by running out of freon twice from poor installation and repair, so I replaced it last year. So I assume I will replace furnace before the A/C unit again. I am all about cheap but do to age and piece of mind, I would just install a new one if it was my money. If it went out next year on you on a nice August day in Houston, you might be willing to pay double the price to be put first one the installation list.


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[Rustic23]

Check this out.

Should I Replace My Heating System | Can I Repair My Heating System.

It's really up to you. Safety would be my main concern and I am not sure you can tell just by looking. I would, and do have a CO monitor in the house.

 

[Texas Proud]

I would look at a few things... age, brand, efficiency...

I think a 20 year old furnace is not going to be anywhere near as efficient as a new one... I would replace it, but I would make sure that the air handler that I had put in would work for either a two stage or variable AC unit..

I have been reading about them and think they would be better at keeping the temp in the range I would want... being in Houston you probably are like I am, with a big enough unit to keep it cool in the hottest months... well, that is too much AC for the spring and fall... so I plan to get a unit that will fix this problem the next time I need one...

My main problem is that I am the opposite of you... my AC is 15 years old and the heater is about 8 ish... so when my AC goes out I will have to replace the air handler... do not know if I have to replace the heater to get this done...

 

[ERD50]

You can probably find the control board on-line for less than $150 (sometimes much less). Pretty easy swap out.

I replaced our air handler fan for $100 (17 YO furnace).

Efficiency really isn't much of an issue if you don't use it much. And if the 20 YO furnace has a draft inducer fan, it is probably mid 80's eff% - it's kind of diminishing returns after that.

As far as safety and CO - you actually can pretty much tell by looking. Contrary to popular opinion, a rusted out or cracked heat exchanger does not cause CO to enter the house. The air in the exchanger is under blower pressure, so a crack allows air into the flame section, not the other way around. And you can see that by watching the flame, and see if it changes when the blower kicks in (usually about a minute after the flame comes on). There are safety switches to detect that, but it is a good idea to do a visual as often as you remember or is convenient, you will see a problem before it gets bad enough for switch to shut it down.

A CO detector is a good idea in any case - a blocked or leaking exhaust pipe could still cause problems.

-ERD50

 

[Rustward]

I would absolutely replace a 20 year old furnace for safety reasons. Recently replaced two of them.

 

[samclem]

In Houston---I'd probably try to get some more years out of your furnace. The minimum use it gets, and will get, might allow you to get another decade out of it, and at that point you might need to replace the AC (including the evaporator coil, and get the latest wiz-bang variable fan speed and other controls that will come with a new AC unit).
ERD50 gives some good tips on checking out the heat exchanger, and sometimes you can also see a crack by getting a bright light in there and looking at the outside of the heat exchanger in a pitch-black room. Get a CO detector regardless.
The fan motor replacement, if it becomes necessary, is an easy thing you can probably do yourself. See video here. A new motor will probably cost between $75 and $200 online.
When it's time to buy a new furnace or AC unit, consider a Goodman brand, it will be much less expensive and shares many components with more heavily advertised consumer models. Here's where you can buy them (and other brands) directly. Compare the equipment being offered by your installer to what you can buy directly there, it's a good way to get an idea of the retail markup and the included advertising costs on consumer-oriented HVAC items.

 

[aja8888]

I put a 4 ton Goodman split system in our previous house. It was a DIY project and went well. The furnace was a 30 year old unit that worked fine and was checked out to be safe. Saved a ton of money not installing a new furnace.

In Houston, the furnaces get used about 2 months out of the year and most are fired on natural gas so they spend a clean life when fired.

Have the furnace checked out and if good, I'll bet it could last a lot longer.

 

[soupcxan]

Ok. We'll fix it and let it ride.