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# pipe size question.

Member Posts: 6
I'm ready to run my underground pipe from my tarm boiler to the heat storage tank in the basement, they will be 130 feet apart. My Question is the boiler outlet is one inch and a quarter dia. the heat exchange coils are three quarter inch dia. what size a pipe can I install based on the distance. Is bigger better or will I have alot of hot water slowly moving through the pipe losing heat underground. I'm also thinking about an emmersion heater to put in the heat storage tank as a back up heat source in case we are not home to feed the boiler. any suggestions will be appreciated about back up heat

• Member Posts: 3

Pipe sizing is uasaly based on flow rate. Given the pipe sizes of the connections, I will give you some sizes, these sizes are based on 300 to 400 millinches per foot of head loss in new copper pipe. All velocities are less than 6 fpm.

3/4"-3.0 gpm

1"-6.5 gpm

1-1/4"-11 gpm

There is real "speed limit" to how fast you can pump water is the speed of sound, but you will noise problems, pipe errosion problems, and huge head requirements long befroe you get that fast.

I hope this helps.
• Member Posts: 3

I would run a 1 1/4" pipe minimum, the one we hooked up had two of these heat exchangers for heating the storage tank and one for heating the doemestic hot water, read your installation manual they tell you alot, the exchangers if two are used ask for a one inch pipe to penetrate the tank the upsize to 1 1/4", also a 1 1/4" copper pipe will carry approx. 160,000 btu, see what btu the tarm boiler you have is
• Member Posts: 6,106
A lot depends on the delta t you chose

to run the system at.

At a 20° delta t you could move 80,000 btu/ hr 8 gpm thru 1" pex at a 4.3 fps velocity with 3.1 feet of head per 100 feet of tube.

At 30° move 120,000 btu/ hr. 8.1 gpm, 4.4fps, 3.1 feet of head per 100 feet of 1" pex

If Tarm is comfortable with a 40° delta tee (150- 190° my choice) move 150,000 btu/hr with 7.6 gpm, 4.1 fps, 2.8 feet of head/ 100 feet of 1" pex

What is the BTU output of the Tarm, and the total distance to and from the boiler locationf? Start with this and build you pipe size to the spec above.

Be sure to provide boiler return protection with any gasification boilers to assure they run hot. I believe Tarm supplies an ESBE 3 way thermostatic valve to pipe in. Be sure to do this!

hot rod

• Member Posts: 414

> There is real "speed limit" to how fast

> you can pump water is the speed of sound, but you

> will noise problems, pipe errosion problems, and

> huge head requirements long befroe you get that

> fast.

The rough speed of sound in water is 5000 f/s, so this isn't much of a limitation. It's going to take a whole lot of power to push 2500GPM (if my math is right) though a 3/4" pipe! I'll leave the non-cavitating pump design as an exercise for the reader.

If you neck down to a pinhole orifice you can get supersonic jets, but the orifice isn't going to stay small very long. I used to walk by the huge storage tanks for the supersonic wind tunnels at NASA Ames. Many 30' diameter spheres feeding to a chamber who's cross section was less that a brick on end. They had signs, lights and sirens for when they dumped the tanks through the chamber.

More fun to pump the system down to a deep vacuum and be able to outwalk the speed of sound.

you can ignore the silly physics now.

jerry
• Member Posts: 6,232
use a system bybass or station bypass....

out on the end of the chosen pipe two "T's" with a few L's and a ball valve will see to it that you have HEAT right at the far end of the tubing at all times. Insulate the lines well.and the transistion from the tarn to the point of use will be negligble coupled with the esbe valve previously refered to you will have a responsive system with a a fair amount of protection of the boiler and the transmission lines to the "Field".
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