Air Conditioning - New Evaporator Coil With New Furnace: Good Idea ?
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Robert111
05-07-05, 09:27 AM
Hello:
Have a 25 year old 3 ton A/C unit (the split type)that has the evaporator section as part of my gas, forced hot air furnace. It does work, sort of, and would like to put off replacing it for another few years, probably.
Will be replacing the furnace now however, with a new Trane unit.
The HVAC contractor suggested, strongly, that we replace the evaporator section now when he replaces the furnace.
Have several questions, please:
a. is this in general a good idea ?
b. some time in the near future, we will, probably, be replacing the outside A/C condenser. Might be replaced with another 3 ton unit, or perhaps a 3.5 ton unit-hard to know or guess at this point.
What potential problems would I be letting myself in for in trying to mesh a new condenser with an already installed evaporator coil in the new furnace ?
c. Best, in your opinions, to do the whole thing at once, and not replace the evaporator coil now ? The cooling produced now is marginal; would be nice if a new evaporator coil would improve the present situation;
is it "likely" to ?
d. Also, would there likely be Brand incompatibilities, or is one evaporator coil like the next, etc.
What else should I be asking about this ?
Much thanks,
Bob
Have a 25 year old 3 ton A/C unit (the split type)that has the evaporator section as part of my gas, forced hot air furnace. It does work, sort of, and would like to put off replacing it for another few years, probably.
Will be replacing the furnace now however, with a new Trane unit.
The HVAC contractor suggested, strongly, that we replace the evaporator section now when he replaces the furnace.
Have several questions, please:
a. is this in general a good idea ?
b. some time in the near future, we will, probably, be replacing the outside A/C condenser. Might be replaced with another 3 ton unit, or perhaps a 3.5 ton unit-hard to know or guess at this point.
What potential problems would I be letting myself in for in trying to mesh a new condenser with an already installed evaporator coil in the new furnace ?
c. Best, in your opinions, to do the whole thing at once, and not replace the evaporator coil now ? The cooling produced now is marginal; would be nice if a new evaporator coil would improve the present situation;
is it "likely" to ?
d. Also, would there likely be Brand incompatibilities, or is one evaporator coil like the next, etc.
What else should I be asking about this ?
Much thanks,
Bob
Ed Imeduc
05-07-05, 09:56 AM
At 25 years old on that AC get a new one now. If you get the furnace and full AC now with Trane you can get a 10 warranty on it all . Stay with one brand for sure dont mix them. This way you can get a higher SEER on the AC if you go all new
ED ;) .
ED ;) .
TigerDunes
05-08-05, 07:51 AM
First of all, I agree with Ed. Now is the time to get a matched complete system of the same manufacturer. Besides the better operating efficiency and comfort, you get the better warranty. And I suspect overall pricing for a complete system would be better all at once rather than purchasing part now, part later.
Now if this is not possible to replace the AC condenser at this time due to budget or some other reason, then yes, I would strongly consider replacing the evaporator section now with a new model. I don't think I would want to reinstall a 25 yr old evaporator coil on a new high efficient gas furnace and then later have it removed(old coil probably is in poor operating state anyway and might fall apart). I suspect if you look at old evap coil and opened it up, your decision would be very easy. If you decide to go in this direction and replace evap coil, you should definitely have in mind the time period that the outside condenser would be replaced along with the type of refrigerant selected so the new evaporator coil and new condenser are compatible. By any standard, you are well past the average life of your existing condenser. You should definitely get a written Manual J heat/cool load calculation so that condenser and evaporator coil are properly sized and matched whether installed now or later.
I personally would not mix an AC condenser and evaporator coil of one manufacturer with a gas furnace of another manufacturer. I know this is done all the time but this is done either due to poor decision making, budget reasons, or perhaps an HVAC emergency.
If you replaced the evaporator coil only and placed on new furnace, I suspect your cooling would be improved but obviously your operating efficiency would be the same with the old condenser.
Regarding evaporator coils, your choices are endless and while there are differences in construction,types, open or closed, they basically perform the same function. Again, I recommend matching the evaporator coil and AC condenser for best results both in comfort and SEER or in the case of a heat pump SEER and HSPF. Purchase a closed high efficient unit. Again, I would not want an evaporator coil of one manufacturer, an AC condenser of another, and a gas furnace of another.
If your intention is to purchase a Trane Var Speed furnace, you will not get the full added benefit of their "Comfort R" feature which increases dehumdification in the cooling process unless you have a properly matched AC condenser with evaporator coil.
My opinion. Hope this is helpful. Good Luck!
Now if this is not possible to replace the AC condenser at this time due to budget or some other reason, then yes, I would strongly consider replacing the evaporator section now with a new model. I don't think I would want to reinstall a 25 yr old evaporator coil on a new high efficient gas furnace and then later have it removed(old coil probably is in poor operating state anyway and might fall apart). I suspect if you look at old evap coil and opened it up, your decision would be very easy. If you decide to go in this direction and replace evap coil, you should definitely have in mind the time period that the outside condenser would be replaced along with the type of refrigerant selected so the new evaporator coil and new condenser are compatible. By any standard, you are well past the average life of your existing condenser. You should definitely get a written Manual J heat/cool load calculation so that condenser and evaporator coil are properly sized and matched whether installed now or later.
I personally would not mix an AC condenser and evaporator coil of one manufacturer with a gas furnace of another manufacturer. I know this is done all the time but this is done either due to poor decision making, budget reasons, or perhaps an HVAC emergency.
If you replaced the evaporator coil only and placed on new furnace, I suspect your cooling would be improved but obviously your operating efficiency would be the same with the old condenser.
Regarding evaporator coils, your choices are endless and while there are differences in construction,types, open or closed, they basically perform the same function. Again, I recommend matching the evaporator coil and AC condenser for best results both in comfort and SEER or in the case of a heat pump SEER and HSPF. Purchase a closed high efficient unit. Again, I would not want an evaporator coil of one manufacturer, an AC condenser of another, and a gas furnace of another.
If your intention is to purchase a Trane Var Speed furnace, you will not get the full added benefit of their "Comfort R" feature which increases dehumdification in the cooling process unless you have a properly matched AC condenser with evaporator coil.
My opinion. Hope this is helpful. Good Luck!
scottg
05-08-05, 01:35 PM
Most of the time when I replace a furnace the evaporator is dirty and needs some good cleaning. With that being said with the labor that would be involved in cleaning and reinstallation there would be just a small charge to replace the coil compared to the labor and chemical charge to clean.