View Single Post
Old 01-30-18, 03:00 PM   #6
Super Moderator
Piwoslaw's Avatar
Join Date: May 2009
Location: Warsaw, Poland
Posts: 926
Thanks: 176
Thanked 98 Times in 80 Posts

Amazing. I mean - the math I like the depth that you are going into (I can see myself doing it exactly the same way).

The COP=2 looks OK, in the sense that 3.6 from the specs is probably a best case scenario, with everything working ideally. You are using a different setup than was used for determining the COP, and you have introduced a lot of new variables which you have not yet completely identified and quantified. But you are getting close with the methodology you are using.

I think that first you will have to find a way to better confirm your flow rates and pressures. With that you'll see much more accurate value of COP.

You can also take an approach which requires much less detailed calculations, but will show how well this setup will work in real life conditions: Test it in a wide range of conditions (low and high outdoor temp, humidity, run time up to a few hours) and see whether the heat pump is providing too much or not enough heat for the space heating needs. Monitor the temperature in the tank, if it goes too high you need more flow to the indoor fan, if it stays low then reduce flow. In this case you don't care about pressures and actual flows, only about adjusting the water pump's speed to get the end result. Of course, You won't know your actual COP, but you will know it works.
Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.
Piwoslaw is offline   Reply With Quote