Older Furnace Has Newer A/C - Replace Both

[ajgilbert]

I have a dilemma. I have a 32 year old Moncrief furnace (installed in 1976). It actually works fine, but it is time for a new, more efficient model. I also have a central A/C installed in 1991 (17 years old). I am trying to decide if I should keep / salvage the A/C to save cost.

Am I throwing money away by replacing the A/C when I replace the furnace?

Is it even possible to salvage an existing 17-year-old A/C when replacing the furnace?

Or, is 17 years plenty of life for an A/C? Should I bite the bullet and replace the whole system?

Any advice would be greatly appreciated. Thank you!

[skippedover]

You're throwing money away every single day so why are you concerned about the cost to replace? A gas furnace installed in 1976 is at best, 65% efficient. So assuming you spend $500/yr. on gas (adjust the actual cost yourself) you're spending about $175/yr. more than you would spend with a 95% gas furnace. So if you had replaced your Moncreif when it was 15-years old, you'd have saved $2,975 on operating costs. The same type of savings is likely to be realized on the AC system. And if you were smart, you'd have a dual fuel system installed and save even more. So why are you even questioning replacement? I'll bet you don't drive a 1976 car or truck, do you? If so, then maybe you should wait until that dies and replace the car/truck, furnace and AC unit all at one time.

[Irascible]

If you plan on staying in the home for any length of time then buy a new air conditioner if you can afford it. If you plan on getting out in the next five years then a new AC is not necessarily going to be of much benefit.

I don't know if S.O. has divined your location, but location is an important factor. Certain areas of the country do great with duel fuel. Some areas don't even know what duel fuel is because it would be absurd to install it. Some parts are hot and humid enough that payback on a new AC is as S.O. implies it might be. In certain microclimates locally it's mild enough that payback is the last reason to buy a new AC. But even in those areas I'd recommend biting the bullet if the customer can afford because if they're in the home for the long term, they'll end up biting it anyway.

If I drive a 1976 truck exactly five times a year, I just might keep the truck rather than buy a new one. I know it's a minority, but some people use their AC's exactly that often. Even if you're more often than that, if you can't afford both (and won't be able to any time soon) but can afford the furnace then just buy the furnace. It's not the end of the world if you do them separately. There's some cost overlap. But it's not for us to decide what's best for you financially.

[bobb25]

Yes, it's possible to save the air conditioning and use it with a new furnace, but it isn't worth it. It can be a lot harder to match the existing coil and plenum to the new furnace, and your current efficiency is very poor.

[ajgilbert]

Thank you for all of your advice. I will ask my contractor about dual fuel. I am not sure it is very popular here in NE Ohio.

I am still on the fence on the A/C - here's why. I am fortunate to have a shady lot and windows that work well, so my house stays cool most of the summer. I probably run my A/C three, maybe four weeks total per year. I have lived here since 1996. That means that, since the unit was five years old it has only been run about 175-200 days total.

Also, its funny that Irascible mentioning getting our the house in five years, because that is roughly my plan. (But I figure a newer system could help the resale value).

So, it has not seen much use and the new (more efficient) unit won't either.

Any additional insight from the pros would be appreciated...

[Irascible]

What I'm about to type is highly subjective and anecdotal in nature. Local markets vary greatly. And of course no one knows what the market will be like in five years.

In my experience new HVAC does little for a home's value. If it adds anything, it's only a small percentage of what you paid - just like pools. That's because most buyers are interested in all things visual. They're not smart enough to really care about the mechanical, at least not like they should. That's even true in a buyer's market. In a seller's market they really don't care. They're so desperate to get in that they blindly take the glib reassurances of their highly suspect realtor. They say: "Don't worry... the home warranty will take care of you." My @ss the warranty will take care of you.

There are good reasons to get a new AC. Home value is usually not one of them.

[bobb25]

A lot of manufacturers make what is called a "cased coil". The dimensions of the case match the dimensions of the furnace. Sometimes supporting a refrigerant coil while trying to install a heater under it, or disconnecting it and reinstalling it on top of a new furnace is more trouble than it's worth. Then you still have your old air conditioner. If you go to sell the house, buyers like to see newer equipment, and a heat pump would let you save a lot of money. It would probably pay for itself in a few years.

[Mrfixit39]

replace it

[bryn]

i would demo everything.New Equipment ups your resale value

[amd]

If the existing unit costs $300 per year or less to operate and it's in good condition, run it until it dies. (Compressor failure, refrigerant leak, or fan motor failure - more minor repairs are worth it)

SEER is a hyped up and often inaccurate indicator of cooling efficiency which doesn't always translate into real savings. (http://www.advancedenergy.org/buildi...s_bulletin.pdf) Duct leakage, quality of installation, and sizing are more important than efficiency ratings.

There are much more cost effective ways to save energy than replacing perfectly good equipment. (Shading, insulation, CFL bulbs, programmable thermostat, etc.)

The truth is that the average home buyer doesn't know **** about HVAC; if it blows cold, nothing else really matters. Same goes for everything behind the walls. (Don't worry about resale value)

[ron3637]

I had basically the same dilemma--twenty five year old gas furnace and 19 year old a/c unit. i decided to go with a new a/c and infinity furnace. What swayed me was the high probability that my old system would fail on either the hottest or coldest day of the year. By replacing the system when it was still working, i was able to shop around for a good price and pick a quality company to install it. By replacing my system in this manner i believe i saved approximately 30% off the cost of the same system if it had failed. I just did not want to be in a situation where i had to make a quick expensive choice when it was 95 degrees outside and my system was broken. Also the cost of installation with the old a/c made no sense, but I live in a warm location with hot humid summers.