EcoRenovator - View Single Post - Evaporator sizing

mejunkhound · 12-22-13, 12:40 PM

by the question:

.. you ran air-to-refrigerant AND water-to-refrigerant concurrently in parallel?
Yes

Did you notice any "hunting" as has been suggested is the behavior of non-identical evaporators in a previous post?
Previous post mentioned 'hunting' for a system without 2 separate TXV, I had 2 separate TXV

Also, are you saying the air-to-refrigerant side shut down when it frosted up?
Yes, since that evap could boil off less refrigerant, the txv on that evap closed down

Was the water-to-refrigerant being drawn on the whole time?
This was a system I built over 30 years ago, but recall I had a tsat that turned on the water when air tem was 50F or below.

Now, having said that, the system I have now operates with 2 separate compressors, which provides redundancy in case of one system failure.
The compressor failed when I was out of town, and DW had a hard time keeping warm, so figured to have 2 separate systems.

What I have now is I replaced the 4t compressor in my air-air HP with a 2T compressor. COP increased from about 3 to 4.5 or so at 40F.
Built the 5T GSHP described in you epic thread as a stand alone system. Above 40F the 2T air-air operates and never freezes with the oversize evap as the coil temp only goes down to 32.1F. The 2T air-air is able to heat the 5300 sq ft house OK at 40F outside.

At 40F outdoor temp, and outdoor thermostat switches over to the GSHP by way of a few custom relay and FET circuits. The air-air HP blower operates for both systems, but at different speeds.

It is all also intertied with the fireplace, which has water wall pipes and 2 old car air conditioner condensers in the ductwork and a hot water circulating pump. When there is a hot enough fire, the HPs are locked out.

May have time later in the week to copy the control schematic and post in a separate thread.

12-22-13, 12:40 PM	#18
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	by the question: .. you ran air-to-refrigerant AND water-to-refrigerant concurrently in parallel? Yes Did you notice any "hunting" as has been suggested is the behavior of non-identical evaporators in a previous post? Previous post mentioned 'hunting' for a system without 2 separate TXV, I had 2 separate TXV Also, are you saying the air-to-refrigerant side shut down when it frosted up? Yes, since that evap could boil off less refrigerant, the txv on that evap closed down Was the water-to-refrigerant being drawn on the whole time? This was a system I built over 30 years ago, but recall I had a tsat that turned on the water when air tem was 50F or below. Now, having said that, the system I have now operates with 2 separate compressors, which provides redundancy in case of one system failure. The compressor failed when I was out of town, and DW had a hard time keeping warm, so figured to have 2 separate systems. What I have now is I replaced the 4t compressor in my air-air HP with a 2T compressor. COP increased from about 3 to 4.5 or so at 40F. Built the 5T GSHP described in you epic thread as a stand alone system. Above 40F the 2T air-air operates and never freezes with the oversize evap as the coil temp only goes down to 32.1F. The 2T air-air is able to heat the 5300 sq ft house OK at 40F outside. At 40F outdoor temp, and outdoor thermostat switches over to the GSHP by way of a few custom relay and FET circuits. The air-air HP blower operates for both systems, but at different speeds. It is all also intertied with the fireplace, which has water wall pipes and 2 old car air conditioner condensers in the ductwork and a hot water circulating pump. When there is a hot enough fire, the HPs are locked out. May have time later in the week to copy the control schematic and post in a separate thread.