The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by dremd

Mad congrats on the leak free loop field!

How about hooking It up to your sanyo for temporary use?

Thanks for the congrats!

Even easier than the Sanyo is the homemade heat pump I already built...

I just need to check it to see if it is still working. I was pretty low on the learning curve when I built it, and it may need to be re-charged.

More soon...

-AC_Hacker

[Daox]

Congrats on the successful test AC Hacker! Thats a LOT of hard work validated.

[AC_Hacker]

Originally Posted by dremd

Mad congrats on the leak free loop field!

How about hooking It up to your sanyo for temporary use?

Thanks for the congrats!

Even easier than the Sanyo is the homemade heat pump I already built...

I just need to check it to see if it is still working. I was pretty low on the learning curve when I built it, and it may need to be re-charged.

More soon...

-AC_Hacker

[AC_Hacker]

Originally Posted by Daox

Congrats on the successful test AC Hacker! Thats a LOT of hard work validated.

...indeed, a lot of hard work...

And thank YOU for seeing this meandering odyssey through.

...but wait! There's more to come!

(* ...to be continued... *)

-AC_Hacker

[dremd]

But wont that require you installing pex in your floors, or am I missing something?

I sooooo appreciate your work on this project, I hope to do similar myself (but mostly for cooling)

[AC_Hacker]

Originally Posted by dremd

But wont that require you installing pex in your floors, or am I missing something?

I was initially opposed to radiant floor heating because forced air is so widespread and it works well. Then I started studying radiant floor heating and I learned that it is better for several reasons:

• Because it utilizes the principle of radiation, temperature stratification is greatly reduced. This solves the problem of too-hot air at the ceiling and too-cold air at the floor.
• Because people need more heat when they are relaxing and 'laying about', radiant-floor heat is advantageous because the heat source (the floor) is closer to where people are when they need the most heat.
• Because heat pumps reach greater efficiency when the difference (AKA: delta T) between the source temperature (ground loop) and the sink temperature (temperature of the water in the floor loop) is smaller. With a radiant floor heating system, the radiating area is very large, so the temperature of the water in the loop can be lower to achieve the required heat output. For instance, a working fluid temperature of around 90 degrees or even lower, is common for working fluid in floors, while working fluid temperatures of 120 and greater is common for working fluid temperatures in forced air heat exchangers.

The reduced delta-T issue and heat pumps is at play when you do a ground source heat pump. It is also at play when you do a radiant floor.

So, yes I have been planning to do a radiant floor all along.

It's not going to be easy, because I live in a very old house and a two-inch thick concrete suspended floor is just not in the cards. But I am looking into ways of getting a high efficiency floor that doesn't weigh as much as two inches of concrete.

Right now, I'm favoring a built-up floor made of layers of Wonderboard brand tile-backer board. I have done some preliminary tests on various materials and Wonderboard looks better than Durock and Hardybacker board.

I have also done some experiments with unusually high thermal transfer aggregate for concrete, but so far, no love. Nevertheless I still think it has promise.

AC_Hacker

[pick1e]

Originally Posted by AC_Hacker

Bathroom & kitchen remodel, it is mentioned in the thread.

I remember now, sorry. The thread is long. I thought you had your floor loops installed.

I didn't see you mention how you were calculating your CoP in that graph. Can you explain it a little more as far as where your sensors were, etc.

Also if you separated the data into different graphs I think it would be more accurate i.e. when you multiply your COP by 10 you also multiply error by 10. If you still have your original data I would be interested to see them separated and axes identified, I for one would find it much more informative.

[AC_Hacker]

Originally Posted by pick1e

I remember now, sorry. The thread is long. I thought you had your floor loops installed.

I didn't see you mention how you were calculating your CoP in that graph. Can you explain it a little more as far as where your sensors were, etc.

Also if you separated the data into different graphs I think it would be more accurate i.e. when you multiply your COP by 10 you also multiply error by 10. If you still have your original data I would be interested to see them separated and axes identified, I for one would find it much more informative.

The test and the graph produced by the test was meant as a first-pass test-of-concept. For that reason alone I'm not inclined to de-construct the entire methodology.

My burden is heavy, my dreams are beyond control.

-Bob Dylan, Dear Landlord

> ...how you were calculating your CoP...

COP is energy out divided by energy in.

You will need to capture the amount of energy going into your system.

You will also need to capture the amount of energy coming out of your system.

...then divide the latter by the former.

If you want specific assistance in setting up your own test, please tell me exactly what you need to know in order to proceed, and I'll try to assist.

I wish you the best in your own project, don't forget the photographs.

-AC_Hacker

[pick1e]

Originally Posted by AC_Hacker

The test and the graph produced by the test was meant as a first-pass test-of-concept. For that reason alone I'm not inclined to de-construct the entire methodology.



> ...how you were calculating your CoP...

COP is energy out divided by energy in.

You will need to capture the amount of energy going into your system.

You will also need to capture the amount of energy coming out of your system.

...then divide the latter by the former.

If you want specific assistance in setting up your own test, please tell me exactly what you need to know in order to proceed, and I'll try to assist.

I wish you the best in your own project, don't forget the photographs.

-AC_Hacker

Please don't be so defensive, I'm simply being curious.

I would be neat to use your test results as a baseline comparison for my setup when I get there. But it's impossible to compare when I don't know what exactly you were testing. Looking at some dots on a graph doesn't tell me a lot if I don't know what it represents.

I understand that "heat" and "chill" were temperature measurements of the two barrels. I have only guessed that "LS temp" and "HS temp" were readings at the heat exchangers, "HS press" and "LS press" were refrigerant pressures at the heat exchangers, and "super heat" and "sub cool" were measurements of the water leaving the exchangers but before mixing with the barrel water.

And for COP I assume you were using a temperature approximation (Th/(Th-Tc) and not volumetric heat gain/loss, but I have no idea whether you were using the barrel temps or the heat exchanger temps or pre-barrel output temps, etc.

If you could elucidate that would be helpful/informative.

[AC_Hacker]

Originally Posted by pick1e

I understand that "heat" and "chill" were temperature measurements of the two barrels.

That is correct, I had thermometers in the water of both barrels. Since the water was vigorously swirling, I assumed uniform temperature.

Originally Posted by pick1e

I have only guessed that "LS temp" and "HS temp" were readings at the heat exchangers

LS temp was measured on the 'Low Side' (cold side) refrigerant line coming from the evaporation heat exchanger. HS Temp was measured on the 'High Side' (hot side) refrigerant line coming from the condensing heat exchanger. These values were used to calculate Sub Cooling and Super Heating, respectively.

Originally Posted by pick1e

"HS press" and "LS press" were refrigerant pressures at the heat exchangers

Yes, I kept my manifold gauges attached when I ran the tests, and recorded the readings every five minutes.

Originally Posted by pick1e

and "super heat" and "sub cool" were measurements of the water leaving the exchangers but before mixing with the barrel water

No, this is not correct. I used the 'LS press' reading to refer to a PT chart for R-290 to see what the temperature should have been at that particular pressure (actually I did a curve fit on the PT chart for R-290 and derived the formula for the entire PT chart in order to save myself from interpolating every value). Then I subtracted the actual temperature from the calculated temperature to determine Sub Cooling.

Ditto Super Heating. I derived values for Sub Cooling and Super Heating, to be used in system tuning. Since the only fine adjustment I could make was refrigerant pressure. I used an excessively high Sub Cooling value to discover that I needed to lower my refrigerant pressure. I did adjust that, and the efficiency increased accordingly.

Originally Posted by pick1e

And for COP I assume you were using a temperature approximation (Th/(Th-Tc) and not volumetric heat gain/loss, but I have no idea whether you were using the barrel temps or the heat exchanger temps or pre-barrel output temps, etc.

Not quite. I used a power meter to determine power into the compressor for each time interval. I also knew the volume, and thus the weight of the water for each time period. Knowing this and knowing the temp change per period, I could calculate the power that was causing the change.

Then COP = power-out / power-in

I calculated this for each time interval.

-AC_Hacker