What is the recommendation for PEX loop spacing when using a ground source water to water heat pump. I've been told that because the geothermal water source is a lower temperature (max 100 to120) then the spacing should be 6" on center throughout rather only around the perimeter. Any help greatly appreciated as I do not want to oversize the system.

That depends on the Btu requirements for each room at design temperature and what types of floor covering wiil be used.

Bergy

Definitely take a whole system design approach. No one parameter (tube spacing, water temperature) suffices to design a system. Room by room and whole house load analysis coupled with careful consideration of floor coverings are all required to ensure an efficient and effective system design.

Selecting geo for radiant can be an excellent marriage, but special care must be paid to design water temperature to make the marriage work.

The house is 5300 sq. Ft 2600 on each floor. Lower floor will have a concrete over-pour to embed the 1/2' pex. Upper floor, most likely gypcrete or similar product. All floors will be tiled. Approximately 50% of each floor will be an open flow (no doors) although each floor will be separated by doors. An initial Heat Loss calculation came back at 81,000 per hour, lots of windows on top of a hill.!!!!

Rovic

Where is this particular hill located?

Nova Scotia Canada

I'm a little suss about the heat loss ( only one so far ) as the house has all new Double pane, Low E, Argon gassed windows with 4" ridged Blue poly in all cavities as well as the ceilings. I'm being quoted on 2 GHP's to cover the heat loss. Makes it expensive.!!!!!

Rovic

For $50 US you can obtain a 60 day license to use HVAC-calc and run your own load calc.

81 kbtuh is a fairly high heat load, but that's a big house in a cold place, and so far north it'll take a big loop system to keep entering water temp at 30 or so; while units will run below that temp, capacity falls off.

Thanks for your reply Curt. What do you think about my initial question about the spacing of the Pex Pipe, is 6" OC alright or is that oversizing things.

Rovic

I am also using 300' circuits with 6 zones, 3 on each floor. Another question, when a pipe is described as 1/2" is that outside or inside and if outside what is the actual dimension. If I am buying 1/2" PEX is that osd or isd.???
Rovic

Sorry, I meant " if inside what is the actual dimension "