BTU question

Tom Towne

Hello Guys

I am trying to find out why my gas useage is so high and if my water heater is functioning properly so I have a BTU question. Here is my water heater.

Bradford/white 50gal 62,000 btu 5months old

Here is my question. Lets assume that the water heater is 65% effeciant. So it is really putting out 40,300 BTU. That is 671 btu/minute. Knowing that it would take 1500 btu to raise the temperature of 50 galons up 30deg f
Shouldn't it take approx. 3 minutes to accomplish this. It actually takes 12 min. Thanks.

Jerry Boulanger_2

One BTU will raise

the temperature of one pound of water one degree F. 50 gallons of water weighs 417 pounds. So, it will take 417 BTU to raise the temperature of 50 gallons of water one degree F. If you want to accomplish that in an hour, and assuming that you don't have any other losses, you will need 417 BTU/hr. To raise the temperature of 50 gallons 30 degress in one hour will take about 12,500 BTU/hour.

Tom Towne

Thanks Jerry

For some reason I was thinking 1BTU was heat needed to raise (1 gallon) not one pound of water. I was thinking wrong.

Robert O'Connor_7

BtU?

You say you have a 50 gal. hwh @ 62 thou btu. What's the incoming water temp?? very important! And why is it only raising the temp 30 degrees? On a standard eff model @ 40f (it is winter) to raise it to 120 or(140) gotta take 20 to 40 min unless it's high recovery, even so, I'd check your math or your watch.