if I get a new furnace, do need new AC?


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Old 05-19-09, 08:26 PM
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if I get a new furnace, do need new AC?

Hi,

My 22+ year old Rheem (RGDA-075A-CR) needs some electrical work and has a really rusty exchanger that I thinking is becoming a safety hazard. I'm thinking I should stop being cheap and replace it.

My question is do I have to also replace the A/C unit (a matching Rheem, sorry don't have any details on this right now) or can the new furnace simply slide in underneath? The old AC ain't great but it's still working and doesn't pose a safety hazard (as far as I understand).

If I should replace the AC, too, how much more (roughly) should I expect this to cost?

Also wondered if there was any freebie Manual J calculation software or web site out there. I have a rough sense of the questions I'll need to answer, but I suppose the devil's in the details...

(Denver, frame construction house, natural gas, electronic thermostat)

Thanks!
 
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Old 05-20-09, 04:24 AM
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You don't have to replace the A/C too, but, if its the original I would highly recomend you do. If you have to replace it a few years from now it will cost more then doing it now and won't be a nice matched system.

Its tough to est cost, to many variables, equipment, scope of work, geographical location, etc.

I don't know of a free manual J, I have seen them for around $50.00 - your contractor should do that for you.

After 22 years I'd say you got your $ out of that Rheem system
 
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Old 05-20-09, 12:08 PM
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I definitely agree that the gear that's in there does not owe me anything!

Just had another thought. I'm a big fan of swamp coolers (I've installed a whole house unit here in Colorado and loved it).

Would it be really bad/whacky to just leave the A/C unit in there until it dies and then just install a swamp cooler? The swamp cooler wouldn't have to use the ducting or the furnace blower and might even reduce the needed furnace size. The dead A/C unit would just sit in place (at least until I was feeling energetic).

I can get a great unit for ~ $1k and installed for about the same again (probably $300 if I did it myself again).
 
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Old 05-21-09, 04:19 AM
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I really can't say, I don't know a whole lot about swamp coolers we don't have them around here, sorry.
 
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Old 05-22-09, 04:20 PM
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I was thinking about replacing the furnace but not the A/C.

Had a sales guy come out and tell me that he thought the A/C coils were icing up and would just rust the new furnace, so I should replace that too.

Does this sound right? The outside condenser is definitely not level in either x or y dimension (doesn't seem to be on a pad). He seemed to think that this and the fact that the line was kinked (which I definitely can't see) was the cause for the ice-up.
 
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Old 05-25-09, 08:50 AM
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Sounds like the sales guy is just trying to push for a sale and trying to get you scared.

But regardless, if your system is 20+ years and you are going to make the furnace investment, you may as well replace the a.c.

Modern equipment is much, much, much more efficient. Yes, it's going to cost you more, but you'll have peace of mind for many years to come and the utility bills will be lower too.
 
 

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