radiant storage

Erich Ruger

Is there a ratio for feet of pex tubing to gallons of water storage.

I have a wood stove I use to heat water for a radiant application. It works great but I want to know if I have enought storage.

Thanks.

KCA_2

It's more a matter of


The size of the storage tank The temp of the stored water and the BTU's that you're attempting to store..

The more BTU's you store the more down time that you can afford for the Fire place..

Rule of thumb... Not that I know of. What temps are you running in the system?

:-) Ken

Erich Ruger

I have 80 gallons of water for a 300 ft loop of pex. I can get it up to about 160 deg and it drops down to about 115.
If I add more storage I can go longer between firings

or maybe another loop. I love the radiant.

Next house all radiant, all v-joint knotty pine, and no sheetrock.

Erich.

hr

The data you need is

length of burn cycle T

output of heat source in BTU/hr Qh

load of the building in BTU/hr Ql

temperature rise of tank from fire on to fire off DT

Lets use a 120 minute burn time. Assume a 100,000 BTU/hr boiler. A load of 10,000 BTU/hr. Run the buffer tank from 130- 190.

Volume= 120 times Qh-Ql divided by 500 times 190-130
I get 360 gallons to fit this example. Well insulated, of course.

Coast time would be 8.33 times volume times delta t divided by building load. So about 18 hours on that 360 gallon tank with a 10,000 BTU/ hr load.

Your 80 gallon tank would be about 4 hours with my assumed load number.

You need some solid data to get a good answer. Your boiler size (output) and building load are a must know. The other number you select.

This is a Siggy formula, he has a nice buffer tank menu on his HDS software for plugging numbers into for quick crunching.

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Erich Ruger

Thanks thats just waht I am looking for . Thanks again for the help.

Erich.