Help design my new system please

[dhaslam]

Originally Posted by buffalobillpatrick

dhaslam,

"That doesn't sound right. I use a calculation of about 6 watts per metre which would be about 7 watts per foot pipe run. I have 1/2 mile of pipe for a 2500 sq' bungalow. Of course being close to passive standard less than half if the circuits are used normally. South facing rooms and kitchen usually have enough passive heat."

what don't sound right?

BBP

It looks like 2 x parallel loops of 250' of 3/4" pex,

with flow of 3.65 gpm in each loop
at Delta T of 20* F , (tank vs. water inside pex)
should transfer about 15 Tons of heat = 180K btus
At a head loss of 7.65'
HL = K x C x L x F^1.75
K = .0034, C = .933, L = 250, F = 3.65
Way more than enough HX for radiant floors.

There are two things 180,000 btus would be too much for a solar heated well insulated house. Also two loops of 250' pex is very little. Spacing between pipes should be no more than one foot apart and they need to be closer where there are restrictions like in bathrooms so 500 feet run covers 500 square feet maximum. The length of pipe needs to match the heat requirement of each room so the pipes may need to be closer than one foot.

[buffalobillpatrick]

dhaslam,

I was discussing the solar tank HX that will provide heat to radiant floor system, when solar tank is hotter than 80* F

The radiant floor will have 3000' of 1/2" O2 barrier pex.

"I will pull heat out via a HX of 3/4" x 500' loop of o2 barrier pex"

Sizing is difficult because I want this HX output to be as close as possible to solar tank temp. within budget.

BBP

[AC_Hacker]

What's the name of the nearest town, or what is your zip code?

-AC

[buffalobillpatrick]

80813

Teller County Co.

Zone 5/B dry

Design temp 2* F
AFI = 2500
Mean Annual Temp. 40* F

HDD 6415

Lat = 38.8*

Altitude 8,800'

Very good Solar, lots of UV, I can get a sunburn in 30 min.

BBP

[buffalobillpatrick]

The ACR tubing that I can find is 3,000psi with "Rated Internal Working Pressure" = 363psi

I don't know what "Internal Working Pressure" means?

BBP

[NiHaoMike]

Here's one good for more than 700PSI working pressure:
WP96602 Copper Coil, For Water, Type L - Grainger Industrial Supply
You'll want 1/2" OD. Note that "for water" just means that you'll have to blow out any dust with nitrogen before using it in a HVAC application. Any moisture inside would be taken care of when you pull the vacuum.

[Mikesolar]

You don't need type L tubing it is only really used for water lines underground and for commercial and resi towers.

As long as the tube meets ASTM B-280 it is good. Don't worry about the pressure rating. A general rule is that the smaller the tube diameter, the higher it pressure rating.

[Mikesolar]

Originally Posted by dhaslam

It looks like 2 x parallel loops of 250' of 3/4" pex,

with flow of 3.65 gpm in each loop
at Delta T of 20* F , (tank vs. water inside pex)
should transfer about 15 Tons of heat = 180K btus
At a head loss of 7.65'
HL = K x C x L x F^1.75
K = .0034, C = .933, L = 250, F = 3.65
Way more than enough HX for radiant floors.

There are two things 180,000 btus would be too much for a solar heated well insulated house. Also two loops of 250' pex is very little. Spacing between pipes should be no more than one foot apart and they need to be closer where there are restrictions like in bathrooms so 500 feet run covers 500 square feet maximum. The length of pipe needs to match the heat requirement of each room so the pipes may need to be closer than one foot.

3.65gpm with a 20F dT is 36,500btu x 2 loops is 73Mbtu. I don't know where 180Mbtu comes from.

[NiHaoMike]

ACR and type L are equivalent.
Copper Tube Handbook: II. Recommendations for Various Applications

Air-Conditioning and Refrigeration Systems
Copper is the preferred material for use with most refrigerants. Use Types L, ACR or as specified.

[Mikesolar]

Originally Posted by NiHaoMike

ACR and type L are equivalent.
Copper Tube Handbook: II. Recommendations for Various Applications

Having taken apart or built a lot of frig systems, I can't remember finding much type L tubing in it but, I am sure someone will use it. Depends on the manufacturer I guess.