MtnDon wrote:I ordered another IR thermometer from an ebay seller as HF wanted more than double. I should have it next week (US shipper of Chinese goods)
I can tell the return line from the radiator is cooler than the incoming line, but can't tell by how much. That raises the questions of how much cooler should we expect it to be? How much heat transfer out of the radiator would be most efficient? The shipping schedule looks like the IR therm and the temperature controller should both arrive on Thursday next. In the meantime I'll go through the plumbing adds 'n' ends and find a valve suitable for testing restricting the flow. With the IR in hand maybe I can make some sense out of it all.
So I did some math....
Assuming you want 1000 BTU per hour.( probably a little high)
1 BTU is the amount of energy to heat ( or cool) 1 lb of water 1 degree F ( its always nice when the english units work for something I'm trying to work out)
1 gallon of water = 8lbs
So assuming that the energy removed from the hot water equals the energy put into the air, then for 1000 BTU
At a flow rate of 1 gallon per minute ( 60 gallons per hour), at temp drop of 2 degrees should give you 1000 BTU per hour
at a flow rate of 2 gallons per minute you would need just a 1 degree drop
at 3 gallons per hour it would be about 0.8 degrees
From what I read online, the attwood gas water heaters are about 10K BTU, so I would adjust the flow rate to try and keep the BTUs at a rate lower than 10K.
Tom