System replacement advice

chitown_frankNovember 14, 2011

Hello All:

Long time lurker; first time poster.

Redoing the basement of my Chicago brick two flat, and tearing out the heat/AC/trunk & ducts. Wife and I live in first floor unit, renter upstairs. Last winter, I blew in R-30 cellulose between our unit and upstairs. When the basement's finished, we'll have 1800 ft2 in our unit. I have three quotes for system replacement (20+ year old system was 100K btu/2.5 ton)

Quote 1

Rheem RGRM07EAMAES 95% variable speed 75K btu

Rheem RASL024JEC 18 seer 2 stage condensing unit with matching coil 2 ton I think

HW 2 stage therm

New trunk and duct work


Quote 2

Heil H9MVX80F12A 95% 80K btu

Heil 2.5 ton 16 seer 2 stage

HW 2 stage therm

New trunk and duct work


Quote 3

American Standard AS-ADHMC100ACV4VA Platinum ZV Modulating 100K BTU

American Standard 4A7A6048E1000A Platinum XM 4 ton 16 SEER

AS two stage therm

Honeywell HNY F300E1035 electronic air cleaner

New trunk and ducts


I like the third quote, not just for price but the gear looks pretty top notch and includes whole house air cleaner. No one's performed a Manual J though, and I'm concerned about three quotes/three sizes for furnaces and ACs.

I've been reading in other posts that heat pump systems might be a good call, but our electric rate is high compared to national averages, whereas gas rate is low.

Any thoughts would be much appreciated. Thanks!

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Just to be clear, this system will serve 1800 sq ft on main floor plus finished area in basement. And the upstairs rental unit has it's own separate HVAC?

I like the AmStd HVAc best as well but have zero confidence that the size of the furnace and AC are correct. Too large!

I prefer the AS perfect fit media cabinet over an EAC. If you do elect an EAC, you want to thoroughly understand the cleaning/maintenance schedule.

You need the AS communicating thermostat for the AS modulating furnace. no substitutes allowed. Don't believe dealer quoted you correctly on the thermostat control.

Of course R8 insulation on ductwork both supply and return. I prefer metal trunk lines, flex OK for runs. What was quoted? If you have any existing hot/cold spots in your home, usually this is poor ductwork sizing and design. This should be pointed out to dealer.

You might want to list your electric and nat gas rate if you want an informed answer about HP viability. Personally, I think it would be overkill with a modulating furnace like the AS quoted.

Those are my initial thoughts and observations.


    Bookmark   November 15, 2011 at 9:48AM
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Hey Tiger, thanks for your observations.

My unit's main floor is 900 sq ft, and basement will be 900 for 1800 sq ft total. Upstairs has its own HVAC and is not contemplated in this job.

I will ask about the AS media cab.

The therm in the AS quote is the AS-ACONT803AS32DA. Sorry for the imprecision.

The ductwork spec'd are metal -- no flex. I have Reflectix double sided (R6) and was going to hit the new ductwork myself after install. One reason we decided to tear out the old ductwork was how poorly sized they were, and my AS guy pointed out several weak points I didn't know about.

Regarding HP, 7.7c KWh electric, 40-50c per Therm NG. Probably won't go with HP, but wanted to throw it out there.

    Bookmark   November 15, 2011 at 11:02AM
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Homeowners do not realize that basement finished areas even with average insulation properties carry small heating and cooling loads if basement is at or partially below grade.

I would want to see a load calc both heating and cooling but my initial thought is to drop to the 60 KBTU mod furnace.

And of course you want damper control on ductwork to balance air flow between the main area and basement.

The 803 while a nice stat is simply wrong for that furnace. You want the communicating stat plain and simple. Again no substitutes allowed if you want full functionality out of that nice furnace.

And I would consider the AS Perfect Fit media cabinet over any EAC!

R8 insulation on ductwork. Where will furnace be located?

That's both cheap electric and nat gas.


    Bookmark   November 15, 2011 at 11:19AM
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I doubt your paying 7.7 cents per KW total price. If you are then upgrade to a heatpump. Often the heatpump model version of the outdoor A/C only costs a few hundered dollars more than the regular A/C model. When an installer is willing to do the upgrade for little or no extra cost above the extra cost in the equipment its always worth it.

Often installers want to charge extra profit for this and it becomes expensive. You would also need an upgraded t-stat if you want to go dual-fuel.

    Bookmark   November 15, 2011 at 11:33AM
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