need advice re HVAC system

dylan67October 2, 2013

Hello, looking for advice, as I know nothing about HVAC systems.

Due to lot size and other factors, we are building a narrow but long addition that includes a basement and two floors, with about 6 registers per floor.

Existing house - one floor, ancient A/C compressor, relatively new gas furnace
Location - MD suburbs near DC, so hot and humid summers

Builder recommended a separate HVAC for addition. I believe that the first one below was the one recommended initially. The second one was in response to our request for a system that would not break the bank due to emergency heat pump use when the winter temps dropped (and no backup heat for addition). HVAC would be in the basement. Please note that we do already have gas -- would just have to run a line to the basement.

Which one would you recommend and why, and which options? Looking for comfort and efficiency over the long run, with an eye on our growing renovation expenses. Any feedback is greatly appreciated! Thanks!

Choice 1:
� Installation of new heat pump duct system with new Carrier 2.0 ton Puron
R410a air handler model # FB4CNF024 with 8 kw heater and new Carrier
heat pump model # 25HCD324A003 rated at 13 SEER and 2.0 tons. New
programmable thermostat to be installed.
� Price includes above equipment, labor, taxes, permit, power wiring,
control wiring, slab, refrigeration piping, sheet metal work, drain piping,
registers, grilles, and warranty.
� All power wiring and gas piping by others.
� All labor and material guaranteed two full years. All parts and compressor
guaranteed ten years. total for this equipment.............$10,000.00
� Carrier 15 Seer heat pump $ 600.00 Extra.
� Carrier variable speed air handler $ 600.00 Extra.
� Carrier Infinity 2 stage heat pump wI Infinity air handler & Infinity wifi
thermostats $3000.00 Extra.

Choice 2:
. � Installation of new duct system for new addition with new Carrier 92%
efficient gas-fired warm air furnace model # 59SC2B040S14-1t0, Carrier
cooling coil model # CNPVP2414ALA and new Carrier alc model #
24ABB342A003. (13.0 SEER; Puron; 2.0 Tons; 10 year compressor
� Price includes above equipment, labor, taxes, permit, control wiring, slab,
drain piping, flue piping, refrigeration piping, registers, grilles, sheet metal
work, and warranty.
� All labor guaranteed two years. AlC compressor and parts guaranteed 10
years. Furnace heat exchangers guaranteed twenty years.
Total Cost for this equipment : $ 10,950.00
� Carrier 16 SEERAIC $ 600.00 Extra.
� Carrier Infinity 96% Efficient 2 stage gas furnace wi Carrier Infinity 2
stage Ale & Infinity wifi thermostat $3200.00 Extra.

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Pricing includes new ductwork? R8 or better insulation properties on ductwork?

What size is addition? Each floor and basement. Basement will be insulated and finished?

How will return air be filtered? You will need a return on each floor.

You need additional quotes. I don't like what's been quoted. Since you have nat gas available, I would take advantage of it.


    Bookmark   October 3, 2013 at 7:50AM
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Unless you have very low electric rates, it makes no sense to be heating the addition with a heat pump if you already using gas in the main part of the house.

General contractors know very little when it comes to HVAC. They also tend to use the low bid HVAC sub-contractor and then add their 10%+ overhead fee. My advice would be to hire your own HVAC contractor directly.

A new construction HVAC project must always start with a load calculation. Any contractor who does not want to do a load calculation should not be considered.

    Bookmark   October 3, 2013 at 8:43AM
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Agree with Mike...

    Bookmark   October 3, 2013 at 9:00AM
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Thanks, tigerdunes and mike_home.

So it sounds like you don't like either choice, but Choice 2 is better than Choice 1, since a heat pump doesn't make sense if nat gas is available.

To answer tigerdunes questions:

Yes, pricing includes new ductwork. Not sure about R8 insulation for ductwork. Do we need this if all ducts are within the insulation envelope?

basement: 454 sq ft with 8 ft ceilings, slab insulation R20, R13 in furring, blanket insulation in mechanical room, rest finished

1st floor: 501 sq ft, 8 ft ceilings, minimun R20

2nd floor: 443 sq ft, 8 ft ceilings, minimum R20

attic: R49 blown in

There are returns on each floor, but not sure how they're filtered.

Can contractors do a load calc by looking at the plans?

If I hire HVAC directly, how does the builder coordinate with him, and what about the loss of the builder's overhead fee? I don't want the process to get too complicated, and want to stay on good terms with my builder.

Could you tell me why you don't like Choice 2, and what you would suggest instead?

Thanks for your help.

    Bookmark   October 6, 2013 at 2:16PM
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Ducts inside the insulated envelope do not need to be insulated.

The contractor needs the sizes of the rooms and windows, and the insulation values of the exterior walls and ceilings to do the load calculation. If the plans has this information then there is no issue.

I would think the builder can work with any subcontractor even if you hired him. You can negotiate what the builder should be paid for working with the builder.

If you want to keep it simple tell the builder you are not impressed with the HVAC contractor and would like to get other bids. See what he says.

    Bookmark   October 6, 2013 at 9:07PM
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Thanks, mike_home. I will tell the builder that we are interested in additional bids and be sure to request a load calculation.

    Bookmark   October 8, 2013 at 10:39PM
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I happen to run across your post and it also happen that I am looking to replace my HVAC at my 2-br condo at Myrtle Beach, SC. I have been quoted for $4K to have the below done:
" removal of the existing Carrier 2 ton split system heat pump and dispose per EPA guidelines. Then install a new Carrier 25HCD324A003 2 ton 13 SEER heat pump condenser and a Carrier FB4CNF024T00 fan coil. Indoor fan coil will have a 5kW heater. " . I think it is reasonable estimate but just want to gather some opinions. Thank you in advance.

    Bookmark   November 11, 2013 at 5:27PM
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