Air Source Heat Pump Project! - Page 2

WyrTwister · 09-28-13, 02:20 PM

I am lost and confused . Why is a reversing valve and a defrost cycle needed , if it is not a Heat Pump ? If it is cool only ?

I am thinking , if you get it to work , there was most likely a remote control that originally came with it ?

God bless
Wyr

hikerjohnson · 10-23-13, 11:40 AM

Wow, I must have missed this message. I am not completely sure why there is a defrost valve, except, I suppose, that it might have been intended to address the possible freezing of the indoor unit in really humid weather.

Either way, the fate of this unit is now sealed - it will be the chiller unit for the girlfriend's flower storage room that I will be building in the basement this winter.

That means I will be stretching the abilities of this unit, as flowers want to be stored at 36F, plus or minus about 2 degrees F. Now, I have had good luck in the past controlling freezers and fridges with a cheap bang-bang type controller off of eBay, called an STC-1000. I think I will be able to hotwire the unit, but will need to come up with a solution to address defrost cycles.

****FEEDBACK REQUESTED ON THE FOLLOWING*****

NOTE: Though I wish I had m@d programming skillz, I just don’t. I have an Arduino, and even after several years of on and off fiddling, I still can’t program my way out of a wet paper sack. With that in mind, I’m trying to stick to off-the-shelf and electromechanical solutions that I understand fully.

I think that a bright idea for a simple and functional defrost cycle might be a light flap that is blown out of the way by the circulator fan, such that when the coil frosts over, and air flow is diminished, the flap falls and makes a connection in a small reed or magnet switch, which then would trigger the defrost cycle (simply operate the reversing valve).

Now, the second part of that is to decide whether just the return of airflow is adequate for terminating the defrost cycle, or if there ought to be a little lag time to ensure complete defrosting.

Any thoughts?

AC_Hacker · 10-23-13, 01:38 PM

Quote:

Originally Posted by WyrTwister

...Why is a reversing valve and a defrost cycle needed , if it is not a Heat Pump ? If it is cool only ?...

Both 'heat pumps' and air conditioners have a hot HX and a cold HX...

Under most conditions, the cold HX will eventually frost up. One way to deal with this is to turn the compressor off for a time period that is estimated to allow the frost to melt, the other way is to activate the reversing valve, which will very quickly melt the frost.

-AC

09-28-13, 02:20 PM	#11
WyrTwister Master EcoRenovator Join Date: Jun 2013 Location: USA Posts: 543 Thanks: 6 Thanked 44 Times in 38 Posts	I am lost and confused . Why is a reversing valve and a defrost cycle needed , if it is not a Heat Pump ? If it is cool only ? I am thinking , if you get it to work , there was most likely a remote control that originally came with it ? God bless Wyr

10-23-13, 11:40 AM	#12
hikerjohnson Submarine Renovator Join Date: Jul 2013 Location: Southern Maine Posts: 35 Thanks: 4 Thanked 5 Times in 5 Posts	Wow, I must have missed this message. I am not completely sure why there is a defrost valve, except, I suppose, that it might have been intended to address the possible freezing of the indoor unit in really humid weather. Either way, the fate of this unit is now sealed - it will be the chiller unit for the girlfriend's flower storage room that I will be building in the basement this winter. That means I will be stretching the abilities of this unit, as flowers want to be stored at 36F, plus or minus about 2 degrees F. Now, I have had good luck in the past controlling freezers and fridges with a cheap bang-bang type controller off of eBay, called an STC-1000. I think I will be able to hotwire the unit, but will need to come up with a solution to address defrost cycles. **FEEDBACK REQUESTED ON THE FOLLOWING*** NOTE: Though I wish I had m@d programming skillz, I just don’t. I have an Arduino, and even after several years of on and off fiddling, I still can’t program my way out of a wet paper sack. With that in mind, I’m trying to stick to off-the-shelf and electromechanical solutions that I understand fully. I think that a bright idea for a simple and functional defrost cycle might be a light flap that is blown out of the way by the circulator fan, such that when the coil frosts over, and air flow is diminished, the flap falls and makes a connection in a small reed or magnet switch, which then would trigger the defrost cycle (simply operate the reversing valve). Now, the second part of that is to decide whether just the return of airflow is adequate for terminating the defrost cycle, or if there ought to be a little lag time to ensure complete defrosting. Any thoughts?