View Full Version : Keep Old Furnace & Condenser?

Charles Li
05-14-2015, 12:46 PM
Getting a new furnace and condenser today. I'm guessing they just throw out the old one. Motors run fine (had different problems that led to the replacement). Should I keep parts (almost 20 years old)? Worth selling parts on CL? I'll be honest, I know next to nothing about motors and still learning woodworking. But, I just wonder if years from now I'll wish I hung on to parts. As of now all I'd think of is a home made dust collector to make out of it. Thanks for any thoughts :)

Morey St. Denis
05-14-2015, 3:05 PM
Doubtful you've provided enough information to render useful advice... Circulating pumps & motors are usually separate plumbing components and wouldn't necessarily need to be replaced if still serviceable. An "AquaStat" thermostatic regulator control will interface with the new furnace and may need replacement, else at least a new thermal probe inserted if you heat with circulating water. You've used the word "motors" plural, so I'm assuming these drive some pumps, otherwise it's called a "blower" for furnace air handling and there's often only one employed indoors for both central heating and AC. What fuel does your existing furnace burn, gas or oil? Was it a reputable brand known for providing reliable service? There's also some recycling value in the boiler metals, but would you want to lug this out yourself?

I'd gather you're staying with R-22 refrigerant for the new compressor/condenser as you're apparently planning to keep the existing evaporator coil and air handler? What is the range of BTU output ratings you're looking at for these HVAC components, refrigerant condenser and furnace? Is this for your home or a separate workshop? What SEER rating will the new condenser provide? Sounds as if you may already have central AC... Will your existing evaporator and fan system fully realize the anticipated performance? Unless you're already set up for heating with natural gas, have you given due consideration to an electrical heat pump system for providing a portion of your heating needs until external temperatures drop below about thirty degrees F? You will find substantial recyclable value in the copper and aluminum components of the AC condenser, once that system is properly pumped down, recovered and purged. These would need to go to a specialty metals recycling yard in your nearby area.

Morey St. Denis
05-14-2015, 4:18 PM
Focusing just on your notion: "all I'd think of is a home made dust collector to make out of it"...

Blower motors are usually fractional horsepower devices and may also turn at lower speed for noise reduction concerns. The cage impeller of your furnace air handler blower is likely too delicate for wood shavings and saw cut-offs without an in-line cyclone separator first. That usually takes it out of the realm of average DIY fabricating skills; also you'd likely be disappointed putting effort and expense into any portable shop dust collector that's under 2 HP and 3400 rpm, at a minimum. However, there are a number of useful home workshop spray booth or attic ventilation tasks a good furnace blower might eventually be suited for, with the right air handler impeller shroud. I'd suggest you might keep this, if so inclined.

As for condenser motors, these are hermetically sealed within the compressor body and fairly useless for any function other than metal recyclable content. The outdoor condenser fan typically gets fully exposed to all weather and frequent spells of 100% moisture; so your vertical fan blade, motor windings and shaft bearings suffer failure at much higher rates than their indoor colleagues. Unless it's under three years old, not a keeper, with very little resale value as these tend to be quite brand specific as to operating specifications and mountings; not readily cross-compatible. Any residual value would mostly be in the copper motor windings.

Charles Li
05-14-2015, 6:02 PM
Thanks for the replies everyone. Clearly this is over my head and not worth keeping anything. It was a complete replacement, furnace, coil, condenser, blower. All almost 20 years old but the motors still ran fine. I just always see people talk about trying to find motors and figure there's one in the condenser and furnace and thought it could be useful. They'll haul it out at the end of the day thankfully :).

Brian Cole
05-14-2015, 9:39 PM
Furnace blower motors can be used to make a great air filter - which is different than a dust collector. There are lots of posts and plans here on SMC about making a air filter from a recycled squirrel cage blower typical of those found in a furnace. I made one and am happy with it. It's no substitute for a dust collector that collects chips and dust at the source, but does a good job collecting airborne dust that your collector doesn't get. Search SMC and you'll find some good info on how to make one.