Question about the hydronic formula

BigErl

When using the hydronic formula, which BTU value do you use? Input, DOE, net, or the value the heatloss tells you.

One more question. Does anyone have a chart or know where I can find EDR values for blackpipe?

jimg

If by "the hydronic formula" you mean Q=GPM x 500 x dT, the BTU you get is the output. This formula assumes you know the GPM and the change in water temperature. The Q is the number of BTUs that the water has lost given the GPM and the dT.

If you have the heat loss of the space and the water temperature drop that you want across your heat exchanger (typically 20F), then you can use this formula to figure out how much water you must circulate.

Hope that helps...

Jim.

Jamie Hall

If you are talking about a boiler -- which it sounds as though you might be -- the Q -- BTU -- which you are interested in is the net.

You can flip the formula around in a lot of different ways. As long as you know two of the three variables, you can figure out what the third will be.

BigErl

Thank you guys. Yes, I was referring to the universal hydronic formula.