HVAC help please!

[Steve Rozmiarek]

I've decided that I want central air and heat in the new woodshop, so started shopping for components. You guys helped me find some good sources for new stuff, but I got to wondering about used components to save money.

Long story short, I have found two used Lennox systems that look good in pictures that meet the criteria. Both are natural gas, I'll need to convert to LP, so assuming I can get that done, any advice on checking them out? I'd really like to find out if I'm going to have problems before I get it all installed.

My plan so far is to take the Fluke and check the motors, look for abuse, and just generally see how they look. Pretty primitive, but neither is installed, so I can't see them running.

[guy young]

but neither is installed, so I can't see them running.

In the motorcycle business, if it is not running I don't buy it. Else you are buying a "pig in a poke"

[Jim Rimmer]

Just my opinion and I'm no HVAC guru, but I would think that most folks don't replace that type of equipment until the repair costs start approaching cost of new. Not installed and being used, I would stay far, far away.

[John Lanciani]

One big thing I'd be worried about is a cracked heat exchanger. Unless you're tearing the furnace apart it could be difficult to spot a crack.

[Jim Neeley]

You could propose what I do when buying a used car... ask the seller if they are willing to have it go into a local repair shop for a "pre-purchase survey" that you'd pay for. If they know it's good they aren't likely to have a problem and you buy a checked out (should be safe) unit.

When dealing with flammable and toxic gasses it may provide you some comfort.

Just my $0.02.. YMMV.

Jim in Alaska

[Ken Fitzgerald]

I replaced a Lennox HVAC with another when the 30 year old AC went bad. During the install the installer pointed out and showed me where the old furnace had a crack in the heat exchanger.

As a child we had a house burn down as a result of a gas leak.

People die annually from carbon-monoxide poisoning.

In my home we have a gas water heater and furnace. I do my own carpentry, plumbing and electrical. I hire professionals to do gas anything!

While I did buy a new car for my wife in 2004, my last 3 personal vehicles I bought used.

Personally, I would buy a new HVAC system. It's worth the peace of mind knowing it's less like to have problems today or in the near future.

But that's just my opinion.

[Phil Thien]

I will be the lone dissenter, I guess. There are a number of reasons units are pulled from service. Perhaps they were relatively new when it was decided a house would be demolished or relocated, so they were pulled. Perhaps they are newer but a new owner of a building wanted something more efficient. Perhaps they are newer but the new owner of a building owns an HVAC outfit and decided to replace w/ a brand they sell/service.

There are a million reasons why they may be for sale.

I'd determine their age, and figure out whether there is any factory warranty left.

I'd ask the seller(s) why they are for sale, maybe there is a legitimate reason (other than there is a crack in a heat exchanger) for them to be available now.

[Matt Meiser]

I put a used AC system in my shop but I knew its history because we took it out of the house and installed a heat pump system. Had I not had a friend who could do the lines, evacuate, and recharge, the cost would have been pretty high to move that system because the contractor really didn't want to get involved lest he get pulled into a mess. It might be even harder to get them to install a used furnace.

Had I bought a complete new HVAC system for the house with a high-seer heat pump and ultra-high-efficiency furnace he was going to move all the stuff to the shop for free other than materials.

[Steve Milito]

The cost of installing HVAC is dependent on the labor of installing the unit, the labor for designing and installing the duct work, the line set, and the refrigerant. The refrigerants are highly regulated by the EPA, can not be discharged into the environment, and need to be installed by a licensed technician. The actual cost of the equipment is sometimes a fraction of the cost of the entire job. Faulty equipment is a nuisance to maintain and customers are never pleased with the costly service charges, costly parts, inconvenience, and discomfort of nonoperational equipment in need of repair. Thus, many HVAC contractors won't install equipment they didn't sell. Additionally, the cost savings probably aren't worth the risk of damaged equipment and the lack of a warranty. I'd look into a new second tier unit such as a Goodman, rather than a used Lennox.

[Mel Fulks]

I've got a Goodman bought about six years ago. We have a lot of confidence in our HVAC guy who uses them in his own home. It has worked well. It replaced a Carrier AKA Bryant sold to us buy a crook who left a 2 ton air handler and 2 1/2 ton compressor ,lasted about 6 years.

[Robert Delhommer Sr]

Personally I feel you will be way ahead in the long run with a new unit unless you like to gamble. It will be a crap shoot. :)

[Jim Andrew]

I have bought a used AC unit, but bought it from a HVAC company, who removed it from a house. The furnace I would prefer to have new, but if your hvac guy has a good used unit, and will install it for a really good price, it would probably be ok.

[Steve Rozmiarek]

My HVAC designer, installer and chief blamee when the whole thing fails, is myself. I maintain and pretty much understand the pile of machine ac systems on the farm. I haven't come across many things that I can't figure out how to do myself, and HVAC doesn't look like the rocket science they charge for. With that bias, I guess it's safe to say I'm a gambler who like challenges...

Will try to learn as much about the history as possible, thats good advice. Saw a bunch on the upper east coast on craigslist, wonder if Sandy swamped them. Want to avoid that sort of thing for sure.

Just talked to the seller, turns out it has a good history, he bought it used with a warranty, didn't do the project it was intended for though, so it for sale.

[Craig White]

+1 for a quality used unit for the shop. Basically buying new ductwork with a free unit. Can always replace the unit when necessary. Must have the ductwork installed before spray insulation.

Craig

[Doug Herzberg]

I put a new Lennox in a rental house 12 years ago. I replaced it 2 years ago because of repeated failures and outrageous cost for replacement parts. Lennox is not the same company it was 50 years ago. Most of the cost of HVAC is markup and labor. Because of federal regulations, you cannot work with refrigerant without a license, so you must pay someone for that part. If you don't know what you're doing, don't mess with gas, either.

I think the way to go used would be to contact an installer you trust, preferably someone you already know, and ask him to watch out for a unit that will fit your needs. His cost for the equipment might be zero and the labor doesn't have to be that much, especially if it's done on his free time.

[Marty Tippin]

If you know anyone in the HVAC business, ask them if they've got a used unit that's in good shape. Units get replaced all the time, sometimes because they're old and crapped out and sometimes because the homeowner wants something newer.

I've just installed an old but perfectly functional propane furnace in my shop, courtesy of my brother-in-law who's been in the HVAC business for years. The family connection resulted in a significant price reduction (read: $0) so I'm not out any money to speak of. If it dies, I'll replace it with another used unit either from him or some other local source. I started with just the furnace for now and will add the A/C coil and compressor next spring.

If you don't have a friend or family member, call the local company you use for your own HVAC service and ask if they have or can save an old system for you -- chances are it'll cost next to nothing and work just fine. If you're worried about things like a cracked heat exchanger, install a carbon monoxide detector close to the furnace and watch it like a hawk the first few times you use it.

Watch Craigslist also for used units - frequently those are offered by local service companies who can make a few bucks instead of hauling it to the landfill. I suppose I might be a little bit more wary of a homeowner trying to sell a unit than an HVAC service company.

The natural gas to propane conversion shouldn't be a big deal though you'll have to source the conversion parts. If it's a newer unit, that shouldn't be a problem; older ones may be a bit more difficult to turn up.

[Matt Meiser]

There's usually a small parts kit available for the conversion--a couple orifices and a spring for example. House and shop furnace and dryer were all converted to propane when installed, then back to NG when they built a pipeline down our road. Save any parts...you never know. We had them, except for the ones from the furnace that the original installers threw out. Make sure it is convertible. Not sure if this is true of some furnaces, but our water heater and propane fireplace were not and had to be replaced.