Installing a Furnace

[Rich Riddle]

We have an old gentleman who belongs to the VFW who has limited funds. He replaced his central A/C in 2009 and was told his 23 year old furnace doesn't have much life left in it. The folks who want to replace the furnace for him now want him to replace the 2009 central A/C. Doesn't quite make sense to me since he has no problems with it. Can one pair a new furnace with an old coil and A/C system? Thanks.

[Dick Strauss]

Yes. It makes it easier for the install team and they make more money without worrying about interfacing old and new parts if they seell you both. They did a new furnace with old AC for our house with no issues. Both parts have to be sized appropriately and the fan speed for the AC needs to be set right to achieve the right delta temperature drop. Other than that, it should work fine if they know what they are doing.

[John Goodin]

I see it frequently. At most the installers may have to move the components a little ( inches) and build a connector out of insulation board if the components are sized differently. Definitely cheaper that replacing the whole system.

[Lee Schierer]

Size of components can complicate the install o a new furnace to older A/C and duct work. However, the desire to keep the old system should have been stated when the bid was requested. Personally, I would look for additional quotes on the same work and also check with the local utility providers as there are lots of rebates out there for installing high efficiency HVAC systems. He may qualify for help paying for the updated system.

[Rich Riddle]

He is in his late eighties and has led a simple life, so many things concerning this situation escape his experiences. Even with rebates, I doubt he could afford both the new air and furnace. The old furnace is a 75,000 BTU 80% efficient one from 1990.

[Matt Meiser]

Every one I've owned they were done separately by those before me and/or by the contractor's I've hired. Furnaces replaced when needed, AC's replaced when needed. If its too hard for whoever looked at it, find someone else.

[Rich Riddle]

Matt,

That seems like sound advice. They are trying to scare him with all the efficiency statistics and asking for about $10k he doesn't have to purchase a "complete" and "compatible" system.

[Lee Schierer]

Even if he just purchases the furnace, many utility companies are offering rebates for newer units. Someone should look into what is available in his state for him. For example. New Jersey offers interest free loans to home owners that upgrade HVAC equipment.

[Jerome Stanek]

Does he really need a new unit

[roger wiegand]

"Doesn't have much life in it" sounds like a red herring. If it is broken and cannot be repaired then he needs a new furnace (but not a new AC, that's just job inflation for the installer), if it is still working and money is a concern I wouldn't touch it. He'll have to live a very long time to save $10K worth of energy. Upgrading to a 95% efficient furnace is worthwhile for most people, but is certainly not necessary.

[Morey St. Denis]

It is expedient for the "professional" installer to replace the AC evaporator coil immediately downstream of the furnace blower / air handler unit. Many older heating systems were never planned for central AC, so the coil enclosure may have had to later been "shoe-horned" in place and may be almost entirely built into existing duct work and barely serviceable. That's the way it is here, according to my experience; with a house built in 1952... What I'd vigorously object to is their attitude of "why should we forego all this potential revenue by not also unnecessarily replacing an outdoor compressor/condenser unit while on the furnace job"?.. These HVAC installers typically take a considerable mark-up on any hardware sold, in addition to service and labor charges for what actually is required on a job.

Find out the original SEER rating of the existing compressor; most decently performing R-22 units of similar condenser area can be made to out-perform many of the more recently mandated R-410a refrigerant systems. If the furnace contractor is competent enough to also do the work of an AC technician, have them measure & record the operating pressure differential across compressor refrigerant taps (highly suggest its while under observation)... If the system can still maintain a substantial pressure differential across the compressor (compared to original specs) then its got plenty of useful life left and only a suitable R-22 coil, perhaps a matching TXV (if presently in use) need be replaced and the system recharged at the worst. If the pressure differential being developed is much below about 225 psig during steady-state operation after a spell, then internal compressor vanes are excessively worn and both units of the split system could well need replacement.

Being told something "doesn't have much life left in it" is ridiculous and intended merely to instill dread and foreboding without facts and measured figures to back it up. When faced with an AC failure this past summer, my solution was to replace only the compressor/condenser unit with a similarly rated, high performing, Used R-22 unit manufactured in 2009!.. Unless it can be shown to be clogged with dust, otherwise occluded, corroded or leaking, the evaporator coil may not need replacement, just a good cleaning or refurbished in place. Get several other opinions before making a decision if those pressure readings look at all to be questionable. Kindly let us know how this develops.

[Rich Riddle]

Just to go over information in case it was incorrectly written. The "new" house on the property was built in 1992 and this is the original furnace for that home. The "new" house had its air conditioner replaced in 2009 with a new one with new A-coil on top of the 1992 furnace. I will keep you updated. Thanks.

[Barry McFadden]

Just to go over information in case it was incorrectly written. The "new" house on the property was built in 1992 and this is the original furnace for that home. The "new" house had its air conditioner replaced in 2009 with a new one with new A-coil on top of the 1992 furnace. I will keep you updated. Thanks.


Almost the same situation here...house built in 1992... we added A/C about 2 years ago to the existing furnace. Had the hot water heater replaced last year (leak,rental).. and the installers were saying the furnace should be replaced because they don't last much more than 20 years...never even considered replacing it till it breaks and it's still going strong..

[Morey St. Denis]

With a build date in 1992, it's not likely a low ceiling basement with coal-fired original furnace and no central AC intended... Even more suspect that their demand to replace an existing coil in known working condition, might save on longer-term expense. Placing an imaginary expiration date on equipment without including details on the brand & model reputation along with readily measured performance figures as compared against original specs is an entirely invalid excuse! There is tremendous variability in service life of HVAC systems based upon installation and operating conditions. Present performance parameters can be readily gauged by an experienced professional. I've seen AC and heat pump systems perform adequately for over 30 years when properly maintained. Also bears considering that healthy seniors generally may prefer warmer temps or higher humidity due to somewhat reduced metabolism concurrent with age. With adequate insulation expected of homes by the 90s, they may not even be working the equipment all that hard during peak seasonal demand. The 2009 AC equipment could reasonably have a lot more life in it if properly handled. Make them produce some verifiable data that shows just how much the existing system may be under-performing.

[Jerome Stanek]

Add to the fact that it is in KY where the heating season is mild compared to further north.

[cody michael]

my furnace was older then that I think 86? I replaced it this year because the fuel oil tank it ran off of was leaking, and I was converting to propane when furnace died, so it was not worth buying a new tank, if the tank would have not been leaking I would still be using that furnace today....