<!--[if gte mso 9]> Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 I have received two very different geo quotes in terms of design and cost.

I have a 3 floor home (including walkout basement) built in 1986 located in Northern Westchester County outside of NYC.

The home is roughly 3500 sf with an additional 1000 sf finished walkout basement.

First Quote – 50k (contractor strictly does geothermal)

Unit: 4 ton climate master 2 stage water to air heat pump.  Installed with electric heater for back up. Phoenix nonpressurized flow center utilizing Wilo Stratos ECM variable speed pump.  1200 feet of 1.25 inch HDPE SDR 11 ground heat exchanger.  2 vertically drilled ground heat exchangers each 300 ft. 

Design: Unit in basement with duct in basement supplying basement and first floor.  Ducts running to attic to supply second floor.

Second Quote – 110k (HVAC contractor)

Unit: 5, 3 and 4 ton climate master units total 12 tons.   Installed with electric heat as backup. Vertical loops not specified.

Design: 5 ton unit in basement supplies first floor.  3 ton unit in basement supplies second floor.  4 ton unit in basement  is  a split unit runs to a 4 ton air handler in the attic to supply second floor.

I would appreciate any advice.  Im confused as how i could have two quotes with such wildly different requirements.  Could an almost 5000 st house only require a 4 ton unit?  

Thanks

Mark
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I would hire someone who isn't trying to sell you anything to review all of the options, including reducing the house's energy usage.

You might want to read this thread.....110k is insane!


http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/79495/afv/topic/Default.aspx

Could an almost 5000 st house only require a 4 ton unit?

Have you or any of the contractors done a heat loss analysis on your home?

That is where they look at your home design, insulation, windows, air sealing, etc. and actually figure out how much heat you will need.

Yes i did have an energy audit done by a non geo person.

He gave me some suggestions to increase the efficiency of the home but did not give me a manual J.

I wrote him last night to provide it - he should have all the info he needs.

Thanks all for the feedback.

3500 plus 1000 sqf in NYC climate built in 1986, 4 tons sounds about right.

The fact that he (#1) is including a Wilo pump with a GV flowcenter into the design indicates that he understands how to make the system very efficient. Not many people do that.

#2 is typical for an HVAC contractor (lets oversize everything!) who does not understand how geo is designed. Why would you need 7 tons for the 2nd floor? Don't walk away from him.....run away...!

What's your zip code? (for weather data/design temperature reasons) There are MANY 5000' houses in the US with heat loads in the 4-ton range, but there aren't many of those in the upper peninsula of MI. But many houses may have cooling loads that are higher than the heat loads.

Twelve tons heating would be a well sub-code and inefficient 5000' house in most of the US, but reducing the load by a good fraction would be cost effective. Twelve tons cooling might be required in a house that size if you have panoramic sunset views through a lot of square footage of clear glass (no low-E) windows, and replacing all of that glass with something better and extremely low-gain could come with a daunting price tag.

Northern Westchester is still pretty temperate compared to upstate- I'm guessing your 99% outside design temp isn't any colder than +10F (the 99% condition for White Plains is +12F). Don't let any body running a load calc use anything below +10F as a design temp- the last thing you want to do is oversize the geo, and even if your heat load is closer to 5 tons it's not clear that there's any payback in sizing the geo that high- sizing to a 95% condition is usually more than enough, with a bit of resistance-heat backup.

With 2x6 fiber insulated wall framing and double panes (and not a huge window/floor area ratio) a code-min mid-80s house could easily come in at 4 tons. If the basement has no foundation wall insulation it's worth putting up an inch or two of foam trapped to the foundation with an unfaced-batt insulated studwall, which would likely knock at least a ton off the heating load, but it probably means messing up your finished basement to get there.

If your windows are thin clear double-panes, (or single panes- were they still legal in 1986?) adding low-E storm windows could be good for as much as a ton of heating (or cooling), or at least a decent fraction thereof, for not seriously-huge money.

But hopefully your auditor figured all of that out for you.

Thanks for all the feedback.
Here is some further information.

In regards to heating and cooling loads:

Bid #1 estimated
heating load- 46,628 btu/hr
cooling load - 34,315 btu/hr
winter design temp 7 degrees F
summer design temp 90 degrees F

Separate energy auditor non geo or hvac
heating load - 87,943 btu/hr
cooling load - 63,260 btu/hr
temps not specified

My zip code is 10597 weather is no different than white plains
The auditor mentioned nothing about changing the windows i do have double pained windows
He did recommend
1 attic cellulose insulation for $12,800 (interestingly the geo contractor frim the 1st bid said he could do that for $1500
2 perimeter air sealing for $4000
3 sloped roof insulation for $5000
4 garage insulation $2600
total $24,000

Thanks for any further input.

I wonder why so much for cellulose in the attic - last I checked I can get an R19 cellulose upgrade for 50-60 cents per SF. I would expect NYC-area prices to be up to 2x mine, but that fails to come anywhere near $12.8k.

Has anyone performed a blower door whole house infiltration test? I'd want that info for the load calc since geo tonnage is quite expensive.

If project contemplates ductwork in an unconditioned attic, consider sprayfoam to seal the attic and turn it into unconditioned space. That knocks 25-30% off cooling loads here in Florida, 15-25% heating.

I don't think your energy auditor knows his job very well. Everyone thinks they are independent and unbiased.

In my experience they all sell something and many can't be persuaded to put a number on your load (man J). Those that can are often out in left field.

In mid MI our design temps are lower (1-6*) and I would guess your house around 50Kbtu.

Waccabuc averages a degree or so warmer in winter than White Plains, according to Weatherspark data sets, so +7F is fully 5F colder than the 99% design temp of +12F for White Plains NY.  With heating/cooling balance point of 65F (typical), that extra 5F adds about 10% to the calculated heat load.

That said, 46,628 btu/hr is a credible heat load at +7F for a house that size, 87,943 btu/hr is not (unless it has literally no insulation.)  With adjustment from using a +12F design temp rather than +7F, that 46.6K comes in under 43K.  If you're upgrading the insulation and air tightness it can likely be cost effectively brought well under 40K, and a 3ton system with some resistance heat backup would be reasonable.

$1500 for attic cellulose is the right ball park, $12,800 has to be a typo ($1280, mayhaps?)

$4K for air sealing is a bit on the high side unless it includes 2" closed cell foam on the entire band joist & foundation sill as well as other things.  For a 1000' basement you probably have about 150' of perimeter band joist (maybe less), and insulating & sealing it with 2" of foam would usually be well under a grand, could even be less than $500, so I'm not sure what the other $3-3.5K is buying you.

Without knowing the area and type of sloped roof insulation or garage insulation it's hard to say how resonable that is.

I just got two other quotes from HVAC contractors $130,000 and $170,000.

I pointed out to the $130,000 contractor that I would never get back my investment. He told me that people who buy geothermal dont do it for the cost savings. Thats obviously not the impression I get from reading these forums and speaking to friends with geothermal.

It seems that there are a lot of get rich quick HVAC preople out there.
Im definitely going to go with the geo only contractor - quote 1 at this point.

Does it makes sense to have a 4 ton unit in the basement with ducts running in the attic to supply the 2nd floor or to have a uniti in the basement and attic. I was told by one HVAC contractor that the first scenario would be a disaster.

Thanks

I just got two other quotes from HVAC contractors $130,000 and $170,000.

I pointed out to the $130,000 contractor that I would never get back my investment. He told me that people who buy geothermal dont do it for the cost savings. Thats obviously not the impression I get from reading these forums and speaking to friends with geothermal.

It seems that there are a lot of get rich quick HVAC preople out there.
Im definitely going to go with the geo only contractor - quote 1 at this point.

Does it makes sense to have a 4 ton unit in the basement with ducts running in the attic to supply the 2nd floor or to have a uniti in the basement and attic. I was told by one HVAC contractor that the first scenario would be a disaster.

Thanks

My 3 ton basement package unit happily pushes all the cold air needed to the top floor master suite

A project wherein we achieved a 45% overall electricity usage reduction included a master suite zone served by 50' of 16" flex duct.

Ductwork in conditioned or indirectly conditioned spaces can do a perfectly good job serving relatively distant, horizontally or vertically, zones if enough room is available to run the ducts.

Posted By jesm on 03 Oct 2012 01:57 PM

Does it makes sense to have a 4 ton unit in the basement with ducts running in the attic to supply the 2nd floor or to have a uniti in the basement and attic. I was told by one HVAC contractor that the first scenario would be a disaster.

Thanks

About 50% of the projects have a single HP in the basement feeding the 1st and 2nd floor, all doing the flawless if the ducts are nicely balanced.

I just got two other quotes from HVAC contractors $130,000 and $170,000.

$12,800 for cellulose?

$130,000 and $170,000 for geo?

The word must be out on you. Do you live in an exclusive community?

Posted By jesm on 03 Oct 2012 01:57 PM
I just got two other quotes from HVAC contractors $130,000 and $170,000.

I pointed out to the $130,000 contractor that I would never get back my investment. He told me that people who buy geothermal dont do it for the cost savings. Thats obviously not the impression I get from reading these forums and speaking to friends with geothermal.

It seems that there are a lot of get rich quick HVAC preople out there.
Im definitely going to go with the geo only contractor - quote 1 at this point.

Does it makes sense to have a 4 ton unit in the basement with ducts running in the attic to supply the 2nd floor or to have a uniti in the basement and attic. I was told by one HVAC contractor that the first scenario would be a disaster.

Thanks

The average cost of residential GSHP system in CT under a rebate program in the last year wa 5.63 tons at $9020/ton, which means the "typical" system come in a hair under $51KUSD, for a system BIGGER than appropriate for your house.  You might take a look a their eligible installers list for any that may cover your part of NY as well.

In other regions geo can be substantially cheaper than in this part of NY/NE, and I've yet to see or hear of a quote for the mythical $20K/3-ton system in MA, but I've seen/heard of several north of $30K.

It (almost) never makes sense to run ducts in an unconditioned attic, but running them up from the basement works just fine.  The HVAC contractor who considers it a disaster is probably not a real designer- and is likely a hack, to be avoided.

Four tons may still be on the high side for sizing though, especially if you're going to tighten up the place (recommended.)  If you have any heating history on this place, what was the fuel, and how much per year?  With a  mid-winter bill with meter-reading or tank-filling dates or a K-factor along with the heating equipment's nameplate efficiency would make it possible to calculate a firm upper bound for the heat load of the "before" picture on the house, independent of construction details.

I could collect one cool night's worth of data and get more accurate load numbers than these quotes.

Thanks for all the feedback.
This is my energy usage from NYSEG my electricity provider for more than a year.
I have electric radiant heat.
My house is close to 5000 sqft but in the winter i had been using approx 50% of the house.  I plan to use more of the house in the winter when i get geothermal.

Also i have wall unit air conditioning.
Does the $9000 per ton you quoted for a typical system in ct include the cost of new duct work?
If not how much in general does that add to the cost of the job?
Thanks


Electricity Usage History   

Read Date	Read Type	kwh on	kwh mid	kwh off
7/24/2012	NYSEG	400	1680.0	640
5/25/2012	NYSEG	0	3640.0	1400
3/22/2012	NYSEG	1280	2120.0	1440
1/23/2012	NYSEG	3560	6880.0	4040
11/22/2011	NYSEG	0	3840.0	1360
9/21/2011	NYSEG	400	1760.0	720
7/23/2011	NYSEG	520	1400.0	720
5/24/2011	NYSEG	0	4400.0	1920
3/22/2011	NYSEG	2360	6480.0	3840
1/29/2011	NYSEG	5120	9560.0	6080
11/20/2010	NYSEG	0	3840.0	1360

Since it's billed every two months rather than monthly it's a bit tough to find an accurate non-heating non-cooling baseline, but we can take a WAG at it. It uses on-peak/off-peak/mid-level usage spelled out separately, it's helpful to use a spreadsheet to add up the totals on each row. In very rough terms it looks like your lower-use 2-month periods run about 2600-2700kwh, and at least some of that has a heating or cooling component, so the baseline is probably something like 2400kwh over 60 days (14,600kwh/year), which is over the national average. If you don't have 3 Tivos running and use only high-efficiency lighting (LED/CFL/fluorescent) you'd probably be in the 6000-8000kwh/year range. Since we're looking for an upper bound, let's assume you're only at 20kwh/day as baseline, and subtract that from a mid-winter bill.

Between 11/22/2011 and 1/23/2012 you used 14480 kwh. That's 62 days, so subtract (20 x 62=) 1240 kwh of baseline and you ge (14,480- 1240=) 13,240 kwh for the presumed heating component of the bill.

Degreedays.net has a local weather station data (KNYWACCA2 is the station ID) but the data is incomplete the nearest one with data covering that period is at the Carpe Photon observatory in Ridgefield CT (station ID KCTRIDGE4 ) From You can download the daily-data from other nearby stations as a sanity check if you like. For the 62 days starting 11/22/11 the base-65 heating degree days adds up to 1771.5 HDD (Use a spreadsheet, clip and paste the relevant days to keep it simple.)

So per HDD you use (13,240/1771.5= ) 7.47 kwh

There are 3412 BTU in every kwh use in a resistance heater (COP=1), so that's (7.47 x 3412 =) 25,588 BTU/HDD

There are 24 hours in every day, so that's (25,488 BTU/24=) 1062 BTU per degree-hour.

Using a design temp of +10F and a heating/cooling balance base of +65F, thats (65-10=) 55F cooling degrees.

So the heat load at 10F is going to be strictly less than (55F x 1062=) 58,410 BTU /hr

Using a design temp of +12F (White Plains) thats only 53 heating degrees, which calculates out at 56,286 BTU/hr

I assume you're heating hot water with electricity, which is probably at least 10% of that (since I gave you a very low baseline, lower that what actually shows up on the bill), so 45-50K @ is truly the right ball-park, and anything over 4 tons of geo would be silly, even if you did nothing in terms of upgrading insulation or air tightness.

Running the numbers using 40kwh/day as the baseline, (since that's what the bills imply) that means you'd subtract 2480kwh from the Nov-Jan bill for

12,000 kwh of heating use over 1771.5 HDD,

which is 6.77kwh/HDD or 23,099BTU/HDD or 962.5 BTU/degee hour

x 55 heating degrees = 52,937 BTU/hr

x 53 heating degrees = 51,102 BTU/hr.

So 50K is about where it lives certainly not more, but not a whole lot less either. With some tightening and spot insulation it's probably possible to bring it down 10% without spending a lot of money.

For $130K or $170K you could buy a "Deep Energy Retrofit" (google the term with quotes for some examples) and probably bring it down to about 15-20KBTU/hr, maybe less, which would buy you more comfort than any amount of geo. NYSERDA even has subsidy money for going that route for NY residents too, but it's a daunting project, particularly if you're living in the house while it's going on. Search the NYSERDA site- it's not the simplest site to surf, but there's a lot of good stuff there.

http://www.nyserda.ny.gov/Research-and-Development/Buildings-Research/Advanced-Residential-Buildings/Deep-Retrofit.aspx?sc_database=web