Pennsylvania New Home in Northeast PA

I am currently building a new 2900 sq ft home in North Eastern PA just north of Allentown. The home will have R21 Batt insulation in the walls, R 38 in the ceiling, air sealing and high performance triple pane windows. The house has 9' ceilings and with a 2 story living room and foyer. The home volume is approximately 35,000 cubic ft. I had a manual j calc done and it came back with a 44,000 Btu heating load and a 22,ooo Btu cooling load. If I decide to include the 1,800 sq ft basement which is insulated with R-10 the heating load increased to 54,000Btu and the cooling load went to 22,500 BTU. I am trying to decide which unit would work best. I got quotes on everything from a 2 ton unit to a 6 ton unit. Each contractor feels they are sizing the unit properly. I would like to use Waterfurnce 5 series or 7 series . Any help would be appreciated?

 

Have you received any of the calculation program reports (like GeoDesigner or GeoAnalyst)? How many quotes did you get?

 

I did get a Geo Designer report but all it show's is a cost comparison to oil heat with a heat pump. Each contractor did there own heat calculations. Getting and apples to apples bid for geothermal may not be realistic but I was not expecting to get 3 proposals that where so different in cost and unit size. After I got the quotes back I hired an engineer to do the load calculation which I posted above. I have not gone back to the contractors yet with this information.

Contractor A
With Basement: 3 ton 5 series w/ a 400' vertical loop
Without Basement: 2 ton 5 series w/ a 300' vertical loop
Contractor B
Without Basement: 4 ton 5 series w/a 600' vertical loop
Contractor C
Without Basement: 6 ton 5 series w/ (3) 300' vertical loops or a 5 ton 7 series w/ (3) 360' vertical loops

 

Contractor M

5 ton water to water, loops to be determined on site. Radiant panels for heating. High velocity duct work for cooling. A buffering tank on the load side to control the heat pump and prevent over cooling.

Mark

 

That's funny. Now you just have to tell me that you have been in business for 30 years and know what your doing and everyone else is wrong. Than we might have a deal.

 

John:

I can do two out of three.

I started installing geothermal when Jimmy Carter added solar panels to the White House.

I think I know what I am doing, look here: lake-erie-indoor-air-service.net

Sadly at my age I know that everyone else is not wrong. There are always different ways to get to one's goal. (See Cleveland Browns)

Mark

 

You engineers calculations look very reasonable for your house description and climate zone. Thus you house performance becomes very predictable in given the standardizes insulation of your envelope.
Assuming your basement, I would get around 53,700 BTU/h for a rough quick and dirty envelope calculation.
If you look at the performances of the heat pumps, either a 4 or a 5 ton 5 series would work fine. You can dismiss the 2 ton quote, and the contractor quoting the 6 ton might not know that the efficiency of the series is significantly less than a 5 ton, and given the your 54 kbtu manual J, a 6 ton is really not needed.
If you want to do yourself a favor, you can get the 4 or 5 ton 7 series and move on. The variable speed unit does not have significant disadvantages if slightly oversized as a 5 ton, but would run amore efficient in part load (lower stages).

Radiant panels would require higher supply temperatures than radiant floors, thus making the heat pump running less efficient compared to radiant floors. Plus high velocity air ducts are also not as efficient and usually noisier, why bother in a new built with inherent deficiencies? Plus a 5 ton W-W does not have enough capacity to cover a 54 KBTU/H load with radiant.

 

I would consider higher performing insulation with vs code minimum and double pane low e windows the 3rd pane costs much and offers less than better insulation.
I don't think you require anything larger than a 4 ton. And attention to the envelope might bring it down to 3.

 

I would second Joe's comment about insulation and be very diligent on air sealing. Do a blower door test before drywall to find your leaks. The minimal cost will pay off for the life of the home. We invested in a higher cost spray foam and spent a lot of time on sealing between framing members, sills, top plates, etc. Our house tested at 1.1 ACH50 on our final test just recently. 4800 sq/ft home including basement and we could probably squeak by on a 3 ton unit. 4 ton would handle our home easily.

 

R-10 insulation seems odd for a basement unless they are gluing foam panels to the walls. Which I doubt a builder would ever do as its labor intensive. If your basement is getting finished consider having spray foam put in it will be much more comfortable. Make sure they are not using fiberglass in the basement.

 

We framed our basement then sprayed 2" of closed cell. Left us room to run electrical later. Our basement has held a steady 65 degrees all winter long without heat.

 

We also did the same thing on the South end of the basement which is our walkout garage. We opted for higher insulated garage doors and sprayed the ceiling with 5" of closed cell. The garage has maintained 55 degrees all winter long. Coldest I've seen it in zero digit weather was 50 degrees.

 

docjenser
Thank you for your input. It is always helpful to get a second opinion from someone who is in the industry who is not bidding on the project.
Joe
I would love to do the whole house in spray foam but than I would not have the money to do the Geothermal. I am going to increase the insulation in the ceiling to in the 1/2 of the house that does not have cathedral ceilings. The windows where upgraded to the highest U .17 and SHGC .29 I could find and I will be doing air sealing. The exterior walls where done the zip walls system and all the seams and corners of the sheathing are taped this is suppose to help with air infiltration as well.
moey
The basement is insulated with 2" rigid foam glued to the concrete.

Thank you

 

John I understand the tradeoffs in options and cost. We just finished our build last year and went through many of the same decisions. If anything, I would try to find the money somewhere to spray foam the cathedral ceiling. This will probably be your largest area of heat loss in the home. 3+" of closed cell will act as a vapor barrier as well.

 

I do not get why Doc thinks radiant panels need a higher delivery temp than floors. Doc, are you a RPA member? Show me.

I know you hate water to water and how I think, so we will leave that out. Prove your statement on delivery temps and why you say they do not work with GEO>

Your friend in Cleveland,

Mark

 

Drop the third pane on your windows to finance the foam.

 

I love water to water, nor do I hate the way you think, but geo looses efficiency at higher supply temperature, especially those needed for radiator, panels and fan coils. That is in contrast to efficiently designed radiant floors.
What is the supply temp of a radiant panel for a certain BTU output versus a radiant floor? Then look up the COP of a heat pump at 90F supply temperature versus the 110F and more needed for radiant panels and fan coils. It is geo 1-O-1.
So I did not say that w-w and panels and radiators do not work with geo, but you take a hit against efficiency compared to low temperature radiant floors, which sometimes is unavoidable in retrofit applications. But if you can design from scratch, like here in a new built, why would you make your radiant inherently inefficient?

John, I second Joe's suggestion. There is a point of no returns for triple pane windows. But a couple inches of foam do wonder for air infiltration sealing. Since you usually per per inch, a couple inches of foam followed by an R layer of fiberglass usually give you the biggest bang for the buck.

 

A friend of mine works for a window manufacture and I was able to buy the windows at a discount so the upgrade to the triple pane was under a thousand. I will look into foam again and see if I can get better pricing. When I originally got pricing it was 15k more. If I can go from a 4 ton to a 3 ton 7 series I would only save 3k after taxes. If I save $400 a year in heating and cooling the return would be 30 years. If I am missing something let me know.

 

Id be surprised that gluing R-10 foam in the basement is much cheaper then having it spray foamed don't forget the rim joists need to have foam panels cut out and glued up not just stuffing fiberglass up there. Also has to be covered with drywall. Lots and lots of labor. On a empty basement someone should be able to come in quickly and spray it. You may want to get a cost breakdown for spray foam some areas like the basement if your planning living space down there would really benefit. Ive glued up foam panels in my basement and rim joists. Its a lot of labor. I would have had it spray foamed but I have a lot of restrictions well pump heat pump electrical panel all making the job more difficult.

Just my 2c...

 

John even your attic was planned at code minimum see what that extra thousand gets you in extra cellulose.