Quote:
Originally Posted by Hv23t
I used the formula that AChacker gave me to figure out COP.
The COP Changes over time with temp so I just did it for total at each hour.
1 HR. COP=3.16
2 HR. COP=2.65
3 HR. COP=2.69
4 HR. COP=2.32
5 HR. COP=2.10
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The reason your COP declines is because the temperature difference between your HX in the water tank and the water gets smaller as the water gets hotter... quite normal.
You are totally successful! For making a heat pump water heater out of junk that you dragged back from the jaws of hell, COP=2.1 is nothing to be ashamed of... and when you average them up, you certainly have genuine bragging rights!
It's possible that you could improve on the performance by using a larger evaporator HX... That just might mean another trip to the dump... maybe a re-design of the basic layout.
But if you built that car that's in your garage, you are no stranger to changing things around.
On the timer thing, you might watch and time the frost build up and melt down. I would suspect that night time would be the worst frost conditions. Then plan your on & off cycles accordingly.
BTW, if you're gonna run your unit with R-290, be sure that the area where it is located has the possibility of ventilation... I'm just thinking about the safety thing. The volume of propane in your unit is pretty small, but best to be safe.
Congratulations on a great job.
Best,
-AC