need advice on choosing a new system

mip6July 29, 2011

Lots of great info on the forum. The more I read the more questions I have.

Currently have a 14 year old York gas furnace with 3 ton ac. Located in attic and supplies our second floor. We are in Maryland. The coil is on its last legs so looking to replace the entire system.

Have had many different quotes & options for many brands and have narrowed it down to 2 different proposals from 2 different contractors.

Option 1:

Carrier infinity 17 2 stage ac 16.7 seer 13eer

Carrier infinity 80% efficient 2 stage variable speed fan 58CVA070-1-12

Carrier coil CNPVP3717a-a

Infinity controller

Aprilaire 2410 filter

10 year Parts & Labor

They also suggested standing it up vertical instead of laying down like the York currently is to help improve airlflow to the opposite side of the house that is always colder due to high ceilings and being over the garage.

One of the other guys suggested using a performance ac instead of the infinity since the performance is similar, infinity compatible and costs less. Does this make sense???

Option 2:

Rheem furnace RGTM07ERBGS 2 stage 95% efficiency

Rheem ac RAPM036JEZ single stage 3 ton 14.5 seer

Rheem coil RCFLHM3621CC

Rheem controller model unknown

10 yr Parts & Labor

I've had several guys say not to put a 95% efficient in the attic due to possible freezing temp's but this guy and several others have said it's not a concern???

He also wants to put the pvc intake and exhaust pipes up into the steel vent currently in place so as not to require any roof/flashing work. Is this okay to do?

They are two different approaches and just not sure which one makes sense...Any feedback would be greatly appreciated.

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The Carrier Infinity 24ana736 and the Performance 24apa736 are equivalent as far as I know. I think the 24ana7 series is being phased out. I don't see any down side of getting the Performance model. I believe the Performance model gets a higher SEER rating.

Is the labor warranty directly from Carrier?

I would be concerned about putting a 95% AFUE furnace in an attic. I have no experience with this, but I have read about problems with condensate lines freezing in the winter. A electric wrap tape can be used to prevent freezing. I am not sure what the contractor proposing for the PVC intake and exhaust will result in a proper installation. I am not sure if I do this if it were my house.

    Bookmark   July 29, 2011 at 10:16PM
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Both of these are very nice systems.

Like the previous poster said, depending on location and winter climate, you do not place a condensing furnace in the attic unless it is heavily insulated. Maryland is probably borderline though.

How is the pricing between the two different systems?

On the Carrier quote, it could be improved if you upgraded to the heat pump model assuming you have reasonable electric rate.


    Bookmark   July 30, 2011 at 9:53AM
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Thanks for all the great feedback.

Installed cost is almost the same, so basically comparing 95% furnace 2 stage fan with single stage ac VS 80% furnace variable speed fan with 2 stage ac...

From an overall energy cost point of view is one better than the other???

    Bookmark   July 30, 2011 at 2:09PM
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The 95% AFUE furnace is more efficient than the 80%.

The Carrier 2 stage has a rating of 16.7 SEER vs. the Trane single stage 14.5 SEER. In terms of the ratings the Carrier is more efficient.

Having two stage vs. a single stage in itelf does not increase the efficiency. However the two stage does improve comfort and help to control humidity. It is possible you will find yourself comfortable at 77 degrees an 40% humidity with a two stage system, vs. 75 degrees and 50% humidity with the single stage. This is where you may see some lower costs.

I have the Carrier two stage Infinity AC. I really like how well it works.

    Bookmark   July 30, 2011 at 3:52PM
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let's look at the numbers.

4647830 Active Systems INFINITY 17 PURON AC CARRIER AIR CONDITIONING 24ANB736A**30 CNPV*3717A**+UI 58CV(A,X)070-12 36600 13.00 16.70

3806719 Active Systems RHEEM RAPM SERIES RHEEM MANUFACTURING COMPANY RAPM-036JEZ RCFL-H*3621 RGTM-07?RBG? 35800 12.50 15.10 1

Rheem has the edge on heating, Carrier on AC.

On overall operating costs, I would expect the Rheem to have the lead because of the 80% eff Carrier vs 95% eff Rheem. However, the Carrier is a nicer system.


    Bookmark   July 30, 2011 at 6:33PM
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