EcoRenovator - View Single Post - Help in hooking up geowater water heater?

jeff5may · 04-09-17, 09:22 AM

Here come some answers:

1. Compressor discharge to top of water heater tank. Liquid (and oil) falls to bottom. Superheat is gobbled up quickly at the top, refrigerant condenses slowly and should start to subcool down low. With the outlet at the bottom, the coolest water will be there to ensure adequate subcooling. Whether or not there is enough condenser tubing depends on your efficiency expectations.

2. Cap tube should connect between bottom of condenser and bottom of evaporator. Liquid enters bottom of evaporator and quickly expands, causing oily froth/foam to travel quickly through. By the time all liquid has evaporated, oil has been carried close to end of evap tube. With the configuration you are running, it makes more sense to put the cap tube up high on the vertical path, rather than down low. This ensures some subcooling in the bottom of the condenser, due to a standing liquid column in your liquid line. If left exposed to ambient air, the small amount of escaping heat would keep flash gas out of the liquid line (window air conditioners run the liquid line through the drain pan for added subcooling).

3. The sight glass should be installed directly upstream from the cap tube, then the filter dryer and liquid line tap (I use a SUPCO copper drier- SUD 111 and SUD 115 have charging valves attached) if installed. This will allow you to see if there is any gas making its way into the cap tube.

Plan on having to adjust the size of your cap tube to make this unit operate correctly... with a modified evaporator, the cap tube is no longer the correct length. Too long a cap tube, and the unit will take forever to heat water and try to freeze your evaporator. Too short a cap tube, and the evaporator will try to feed your compressor liquid. Either leave extra tubing in that can be cut and spliced or install some flare fittings on both sides of the cap tube assembly. I like the ball valves with flares on both sides for obvious reasons.

4. The muffler that is built into the compressor inlet also acts as a suction line accumulator. When the unit first starts, the bulk of the refrigerant lies in the evaporator as liquid. The accumulator catches this liquid before it has a chance to enter the compressor. Once sufficient vacuum is pulled, the refrigerant boils off and is pumped to the high side. The screen on the suction line in the muffler is not considered a filter, it is there just to catch any coarse particles that would cause damage to the compressor. Leave it as-is, let it do its job. If you are concerned about contamination, install a liquid line filter drier in the liquid line near the cap tube.

Since you are using a digital controller, why not add some extra sensors to the unit when you build it? Thermistors and digital thermometer sensors are cheap, and will enable you to log whatever data you want.

Looks good so far! I wish you luck in your build.

04-09-17, 09:22 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Here come some answers: 1. Compressor discharge to top of water heater tank. Liquid (and oil) falls to bottom. Superheat is gobbled up quickly at the top, refrigerant condenses slowly and should start to subcool down low. With the outlet at the bottom, the coolest water will be there to ensure adequate subcooling. Whether or not there is enough condenser tubing depends on your efficiency expectations. 2. Cap tube should connect between bottom of condenser and bottom of evaporator. Liquid enters bottom of evaporator and quickly expands, causing oily froth/foam to travel quickly through. By the time all liquid has evaporated, oil has been carried close to end of evap tube. With the configuration you are running, it makes more sense to put the cap tube up high on the vertical path, rather than down low. This ensures some subcooling in the bottom of the condenser, due to a standing liquid column in your liquid line. If left exposed to ambient air, the small amount of escaping heat would keep flash gas out of the liquid line (window air conditioners run the liquid line through the drain pan for added subcooling). 3. The sight glass should be installed directly upstream from the cap tube, then the filter dryer and liquid line tap (I use a SUPCO copper drier- SUD 111 and SUD 115 have charging valves attached) if installed. This will allow you to see if there is any gas making its way into the cap tube. Plan on having to adjust the size of your cap tube to make this unit operate correctly... with a modified evaporator, the cap tube is no longer the correct length. Too long a cap tube, and the unit will take forever to heat water and try to freeze your evaporator. Too short a cap tube, and the evaporator will try to feed your compressor liquid. Either leave extra tubing in that can be cut and spliced or install some flare fittings on both sides of the cap tube assembly. I like the ball valves with flares on both sides for obvious reasons. 4. The muffler that is built into the compressor inlet also acts as a suction line accumulator. When the unit first starts, the bulk of the refrigerant lies in the evaporator as liquid. The accumulator catches this liquid before it has a chance to enter the compressor. Once sufficient vacuum is pulled, the refrigerant boils off and is pumped to the high side. The screen on the suction line in the muffler is not considered a filter, it is there just to catch any coarse particles that would cause damage to the compressor. Leave it as-is, let it do its job. If you are concerned about contamination, install a liquid line filter drier in the liquid line near the cap tube. Since you are using a digital controller, why not add some extra sensors to the unit when you build it? Thermistors and digital thermometer sensors are cheap, and will enable you to log whatever data you want. Looks good so far! I wish you luck in your build.