btu calc

John H.

> how do you determin btu with a 120 deg water and <BR>
> a 0 deg delta t in a radiant system <BR>
<BR>

gino_2

btu calc

how do you determin btu with a 120 deg water and a 0 deg delta t in a radiant system

Terry

BTU = GPM (flow) x Delta-T (temp diff) x 500.72 (480 for glycol)

Flow rate unknown, but since delta T is 0, BTU = 0

there you go.

John H.

Are you saying

the delta t from the supply to the return is 0? If yes your btu output is 0

gino_2

i understand that calc but if the water is constant at a 120 deg with no way to shut off the radiant loops would you not have a very warm floor

Eugene Silberstein 3

How can you have...

One Quick Question Gino.

If you have a zero-degree delta-t across your radiant loop, that means that the temperature of the water leaving the loop is the same as the temperature of the water entering the loop.

I am suspecting that there is some miscommunication here or, at best, we need a new thermometer. At any rate, your heat transfer will be zero since there is no change in temperature.

Mike T., Swampeast MO

As others mentioned, with zero drop in temp from supply to return there is zero energy leaving the system. With 120F water the ONLY way this could happen is if EVERYTHING in the system is also 120F.

If this is a functioning heating system then you may be measuring at inappropriate locations: e.g. the actual supply to the loop (after the boiler circuit) but the return measured after mixing back into the boiler circuit.

There could also be a small drop in temperature within the accuracy range of whatever device you're using to measure temperature. In that case, the flow rate is likely much greater than necessary. If this emitter circuit is actually heating the space in moderately cold weather with such low temperature drop then the flow rate is likely so high noise and/or velocity-induced erosion will be problems.

Terry

if delta T is nil.
water temp can be 50F or 200F. BTU is still 0 (NIL)

Kniggit

yes, but why are you designing with any thermostatic control?

Somethiing Else

0deg. delta T

If the delta T is 0, than that means you r heating loop is not giving up any heat. Maybe your heating loop is 100% insulated, and you have the wrong pump sized for the system. How and where are you measuring the delta T?

Unknown

yes, if the flow rate were very high you'd have a very low delta T... maybe, in some theoretical world, a fraction of a degree even... but the flow rate times that delta T (with the constants) would determine what the BTU transfer is.

If BTUs are transferred out of the pipe, you have a Delta T. You may have a hard time measuring it, but it would be there

Kniggit

that should say without... not with oops