Building a new home..2 units OR 1 unit with zoning? Newbie needs help..

[lithnights]

First off, I am an HVAC newbie so forgive me if I don't use the correct terminology below. Here we go..

I am having a home built this spring. The home is about 3200 sq ft. 1600 on each floor. Attached floorplans. It will have an electric heat pump with propane backup. I am in southeast PA. I also plan to run a wood burning stove to supplement heat in the winter, although I know this shouldn't affect the HVAC design.

I'm wondering if such a house needs 2 different heating/cooling units (I assume one in basement and one in attic) or does it just need one bigger unit, but with some kind of zone setup where dampers open and close the ductworks based on different thermostats?

My understanding is that the builder will send the houseplans to the HVAC folks (he says he sends them to York) and they will come up with the best HVAC plan. I know they should use a manual J to figure things out, but how do I know that their decision is the right one? i.e. how do I know the builder doesn't say to use just one unit b/c he wants to save money?

So my questions are:
1. For such a home, just looking at the floorplans, does it appear I would need 2 units or just 1 unit with zoning?
2. How does one make sure the builder's decision is the right one? I plan to be in the home for the long haul, and I've heard over and over to make sure they get the HVAC and ducting done right.

Thanks in advance!

[NY2GA01]

So my questions are:
Q1. For such a home, just looking at the floorplans, does it appear I would need 2 units or just 1 unit with zoning?
Q2. How does one make sure the builder's decision is the right one? I plan to be in the home for the long haul, and I've heard over and over to make sure they get the HVAC and ducting done right.

Thanks in advance!

A1: I would venture to say that you would get two systems, and two would be the better design than one system for a few reasons.

A2: NOT ONLY YES, BUT HELL YES!

Just like anything else, get a second opinion (and maybe a third), and see if you can get two (or may three) matching designs.

There is a lot that goes in to a system to make sure you achieve optimum comfort control.

When building, the biggest thing you can do to ensure you achieve optimum comfort control is: don't skimp on the insulation, and windows and doors.

I don't care how great your system is, with out proper insulation, and good window and doors you are pissing in the wind.

Please watch this video, one of the best ones out there imo. http://www.youtube.com/watch?v=g37riSkyZzM

[George2]

I would probably opt for 2 separate systems to keep the air noise down (two 3 ton vs one 5 ton blower). I like geothermal system(s) but I also like the foam insulation. I would do some load calculations (to find the payback) as to the best bang for the buck.

Remember, the better insulated home requires smaller HVAC. So the extra money spent on insulation saves on the cost of the HVAC equipment.

[George2]

One other thought........I would keep all a the HVAC out of the attic. Equipment and ductwork.

[teddy bear]

I would probably opt for 2 separate systems to keep the air noise down (two 3 ton vs one 5 ton blower). I like geothermal system(s) but I also like the foam insulation. I would do some load calculations (to find the payback) as to the best bang for the buck.

Remember, the better insulated home requires smaller HVAC. So the extra money spent on insulation saves on the cost of the HVAC equipment.

If you put a system in the attic, the attic roof must be insulated to avoid condensation problems with ducts winter and summer.
Also fresh air ventilation is a must. YOu need a fresh air change in 4-5 hours when occupied to purge indoor pollutants and renew oxygen. A simple reliable device for thiw is a whole house ventilating dehumidifier like the ULtra-Aire. This will provide filtered fresh air to the whole house and maintain <50%RH during wet times of the year.
Regards TB

[dan sw fl]

FIRST
Thermal Envelop Spec

Ceiling R-45 ... spray foam on underside of roof ... ALL ducts in conditioned space
Walls R-16
Windows U < 0.3
Air Change per Hour (A.C.H.) < 0.25
MAX flex duct length 9 feet


ACCA Manuals J & D -
-- approved by PA Professional Mechanical Engineer (ME)
-- thermal envelop, HVAC equipment and duct work inspected and accepted by PA ME

HRV at ~ 60 CFM per floor
http://www.broan.com/products/lifest...f-d721c95ad1a0

Builder needs to Guarantee performance < 16,000 BTU/Hr @ 10'F per floor.
Strip emergency heat - 2 kW [2]/ Floor
Operating cost of strips to be paid by builder - part of the performance Guarantee

SECOND
2 Units
Page 42
http://www.upgnet.com/PdfFileRedirec...ytg-a-0410.pdf

http://www.paelectricrates.com/cityp...ntown&state=PA

http://www.climate-zone.com/climate/...nia/allentown/

[dan sw fl]

i.e. PECO $0.096 / kW-Hr after 1Apr13

http://www.papowerswitch.com/shop-fo...eco-energy/rh/

Builder and mechanical contractor/HVAC should pay any electric cost for heating > $600 / year for 10 years
( pro-rated to $0.096 / kW and 5,000 Heating Degree Days [ HDD])

If there are only 4,000 HDD in a Winter season, any annual electric heat cost > $480 to be paid by builder/ HVAC installer.
........................6,000 HDD .................................................. ..................> $720 ........."....... " .......... "...............

[garyed]

If it were my house I would not even consider having one system zoned. Two systems is the way to go. The only reason to put in one system would be to save on the initial cost of installation. Compared to the cost of building the whole house it is a minimal savings with much more possible negative consequences than positive.

[dan sw fl]

For any additional ventilation needs, make Sure your installer is Fully qualified.

http://blip.tv/eyehandy/how-to-insta...vannah-5471801

[jacob-k]

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[dan sw fl]

If it were my house I would not even consider having one system zoned. Two systems is the way to go. The only reason to put in one system would be to save on the initial cost of installation. Compared to the cost of building the whole house it is a minimal savings with much more possible negative consequences than positive.

Zoning co$t is NOT Negligible. I am not a contractor, but - one might guess that zoning $$$ might be 'in the range
of half' of a second system. So, ... where's the Real savings __ only 'A FEW $$$'s' in the builder's pocket.?!

How many actually know how to install & set-up properly.
How much tweaking is generally done ( + paid by HomeOwner $$$) to satisfy the customer's comfort level over the first few years of operation?!

[jpsmith1cm]

jacob-k

This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

You can find the rules for posting and qualifications here.

Additional infractions may result in loss of posting privileges.

[arc8]

I vote for one system.
If you know how to design, then it should not be a problem with only one system, especially when you mentioned a dual-fuel set up... you have your backup already built-in!
Why two, it's not very green or cost effective? More energy is used up and each system will probably be oversized a bit due to the equipment limited small sizes manufactured.

If your serious, then forget the equipment in the attic idea. Sized the duct/s correctly, never ovesize, and seal everything: ducts, house etc...
and don't forget a good fresh-air system....

Note: the only time I would install two systems is when they need more than 5 tons of cooling.

[George2]

I vote for one system.
If you know how to design, then it should not be a problem with only one system, especially when you mentioned a dual-fuel set up... you have your backup already built-in!
Why two, it's not very green or cost effective? More energy is used up and each system will probably be oversized a bit due to the equipment limited small sizes manufactured.

If your serious, then forget the equipment in the attic idea. Sized the duct/s correctly, never ovesize, and seal everything: ducts, house etc...
and don't forget a good fresh-air system....

Note: the only time I would install two systems is when they need more than 5 tons of cooling.

Normally I would go with one system except he's thinking of using heat pump(s). One (1) five ton (approx. 45,000 Btus) HP won't do him much good. He'll be on back up (electric) heat all the time.

[garyed]

Zoning co$t is NOT Negligible. I am not a contractor, but - one might guess that zoning $$$ might be 'in the range
of half' of a second system. So, ... where's the Real savings __ only 'A FEW $$$'s' in the builder's pocket.?! ...................

When I said the savings is minimal I was comparing it to the cost of buildning a whole house. If it costs 20% less to do a zone sytem & the HVAC costs afre 5% of the cost of building the house then we're only talking about 1% of the total cost & probably even less than that. The only reason builders like to do one zone system is so they can cut costs plain & simple. It has nothing to do with what is best for the house. If the HVAC guy told them it would cost more to do one zone system then the builder would recommend two separate systems.

[dan sw fl]

The only reason builders like to do one zone system is so they can cut costs plain & simple. It has nothing to do with what is best for the house. If the HVAC guy told them it would cost more to do one zone system then the builder would recommend two separate systems.

LESSON LEARNED ... ALWAYS TELL BUILDER a single system With Zoning
is MORE expensive due to planning, dampers, EXTRA Ducting + amount of labor.

[lithnights]

A1: I would venture to say that you would get two systems, and two would be the better design than one system for a few reasons.

A2: NOT ONLY YES, BUT HELL YES!

Just like anything else, get a second opinion (and maybe a third), and see if you can get two (or may three) matching designs.

There is a lot that goes in to a system to make sure you achieve optimum comfort control.

When building, the biggest thing you can do to ensure you achieve optimum comfort control is: don't skimp on the insulation, and windows and doors.

I don't care how great your system is, with out proper insulation, and good window and doors you are pissing in the wind.

Please watch this video, one of the best ones out there imo. http://www.youtube.com/watch?v=g37riSkyZzM

So when you say 2 would be better for a number of reasons, what would they be?

Regarding the 2nd/3rd opinions, how would one do that if the builder is in charge of the HVAC and uses a certain HVAC sub? Does one ask them to go out and get a 2nd opinion, or does the homeowner find that 2nd opinion?

I agree, insulation is key. I am upgrading the Silverline (by Andersen) windows to Andersen 200 series. I am planning on doing 2 inches of spray foam throughout the exterior and attic floor. The house is 2x6 (not 2x4). I am planning on having R50 or so in the attic.

[lithnights]

I would probably opt for 2 separate systems to keep the air noise down (two 3 ton vs one 5 ton blower). I like geothermal system(s) but I also like the foam insulation. I would do some load calculations (to find the payback) as to the best bang for the buck.

Remember, the better insulated home requires smaller HVAC. So the extra money spent on insulation saves on the cost of the HVAC equipment.

I looked into geothermal but I simply can't afford it (even with the federal tax credit and the long term savings). Doing the spray foam based on the builder's cost estimates.

[lithnights]

One other thought........I would keep all a the HVAC out of the attic. Equipment and ductwork.

If not in the attic, then both units in the basement?

[lithnights]

I vote for one system.
If you know how to design, then it should not be a problem with only one system, especially when you mentioned a dual-fuel set up... you have your backup already built-in!
Why two, it's not very green or cost effective? More energy is used up and each system will probably be oversized a bit due to the equipment limited small sizes manufactured.

If your serious, then forget the equipment in the attic idea. Sized the duct/s correctly, never ovesize, and seal everything: ducts, house etc...
and don't forget a good fresh-air system....

Note: the only time I would install two systems is when they need more than 5 tons of cooling.

I agree, if one knows how to design.. unfortunately I don't, so I'm dependent on the HVAC feedback to the builder. : )

I guess we'll soon find out if I need more than 5 tons of cooling..