Sizeing copper pipe Heat Exchanger

[ErikAkia]

Hello,
I have been trying to figure out how to size the copper pipe loop that I need to run through my storage tank.
I had the house radiant floor system designed and it specs at 66K BTU at 13.6 GPM and a 3.8 head loss
I am also planning on running another zone to my DH HX tank that would be additional.
Is there a rule of thumb for BTU load on a the DH?
I have been reading the posts and it seems that there is an excel spreadsheet that can help size the copper pipe needed? Can someone send me a copy?
Or is there a simple surface area of pipe number that I am missing?

Thanks
Erik

Edit:
I forgot to add that I plan on keeping the tank at least 160 degrees F and that the radiant floor needs 134 degree F water.

 

[Hunderliggur]

Erik,

Sorry you didn't get any replies - probably missed in the Thanksgiving rush.

I am not a coil sizer, but STSS tanks do sell a coil and it has specs (size, btu, etc.). That would be a start. I would not worry about your radiant floor needing "135F" water. I can see "not greater than 134F" to protect the flooring. I have 3/4" bamboo over 5/8 ply and run my system at 135F or less. It works fine down to about 100-110 temps but the higher temps give more BTUs/hr.

Maybe this will bring your thread back to life. A system diagram would help too so we can all comment on another installation ;-)

Good luck!

 

[dswitham]

I can't answer about the coils for the radiant heat, but I can tell you what we did for our DHW. We took 100' of 5/8" refrigeration copper coil and formed a 16" diameter coil with it and put that in the top of our tank. It has worked beautifully for us. Where it comes out of the tank we put a mixing valve so the water would be a safe temp. Our water heater was an on demand tankless electric. After we put the coil in the tank, we shut the electric heater off and we have had hot water from the storage tank since. Even with three showers in a row we didn't run out of hot water. I was amazed how well it worked. When it came time to fill our hot tub, I turned down the mixing valve to get 100 degree water out of it and filled the tub with hot water, all 450 gallons. Eventually I will get the tub heated by the boiler with a heat exchanger, but for now at least I can fill it with hot water and save that much electric.

 

[ISeeDeadBTUs]

No idea.

Read this book http://www.heatinghelp.com/products...Practical-Guide-for-the-Nonengineer-Installer

 

[ErikAkia]

I will look into getting that book.
I did read Modern Hydronic Heating (Second Edition) by John Siegenthaler several years ago before my house burned to the ground and I no longer have access to it.
I do not remember a lot of it since I never put it into practice.

Thanks
Erik

 

[ErikAkia]

I am going to start a new thread with more introduction, info and of course questions.

Thanks
Erik

 

[bigburner]

"I had the house radiant floor system designed and it specs at 66K BTU at 13.6 GPM and a 3.8 head loss"

Please include the rest of your math in the new thread

 

[ErikAkia]

I found this chart that I think would help but I am not sure what they mean by Friction Head and the unit milli-inches.
http://www.engineeringtoolbox.com/copper-tubes-heat-capacity-d_476.html
Any ideas?

I found a good deal for 100' of 1" soft copper and was going to use is it as one loop of 100' and had figured that since that was 1" then it would make sense to use 1" manifolds to the 3/4" zone valves but now I am a bit worried that it is not big enough for the flow of 14 GPM.
Would it be better to make two parallel runs of 50'?
I also got a 40' role of type K 1-1/2"
I had planned on using it for the boiler piping but could switch that to black iron and use the 1-1/2" on the demand side.
Thoughts?

Thanks
Erik

 

[bigburner]

10 gals per minute = 6.71 friction loss ft. per 100 ft of copper pipe

20 degree delta - T @ 10 GPM = 100 MBH