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jeff5may · 08-02-16, 08:42 AM

Sorry I haven't been lurking or posting as much as usual lately. The flood gates have opened at work, and I'm on a 7 day schedule. Last day off was the 4th of July, next day off will be Labor Day. Good for the wallet, not so good for hobbies. Projects are deadlocked and just keep piling up...

Jdom,

That rig you have built looks like it should dominate and save you money on your power bills. Using the thing just like it is should work well for either heating or cooling. Setting your system charge should be done at high condenser temperature conditions. If you don't want to mess with cap tube length, make sure you have at least a few degrees of subcooling, and that the evaporator is not flooding.

I have a question: what is the silver bell-shaped thing in parallel with the cap tube? I'm envisioning it being a CPEV. If so, it can prevent freezing your evaporator BPHE, but you will need a suction line (slobber box) accumulator to keep from flooding your compressor.

Your 270V compressor should run just fine off 240V line current, but starting torque will be somewhat limited. A 2 or 3 minute short cycle timer box should be used to let pressure equalized between run cycles. That way, you won't have problems with the compressor stalling and drawing LRA current due to insufficient starting torque. In any case, a hard start kit will smooth the starting spike and provide a big jolt to kickstart the compressor if you need it.

As for reversing the cycle, I myself would accomplish this on the water side of the two heat exchangers, rather than reversing the flow of refrigerant. Those HX's run much more efficiently, with higher delta T, when they are plumbed in counterflow. Reversing the refrigerant flow means that unless you also reverse the water flow, the unit will run less efficiently in one mode than the other. Also, reversing the water flow requires less robust methods and components.

Whatever you do, make certain the evaporator HX can never freeze! Brazed plate HX's are very intolerant of Freezing conditions: they will split open like a tuna can in no time and spew their contents. Be sure to use antifreeze, and include some sort of frost sensing thermostat with flow sensing and compressor cutout control to eliminate all doubt. Other ecorenovators have been unpleasantly surprised by this event.

08-02-16, 08:42 AM	#1922
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Sorry I haven't been lurking or posting as much as usual lately. The flood gates have opened at work, and I'm on a 7 day schedule. Last day off was the 4th of July, next day off will be Labor Day. Good for the wallet, not so good for hobbies. Projects are deadlocked and just keep piling up... Jdom, That rig you have built looks like it should dominate and save you money on your power bills. Using the thing just like it is should work well for either heating or cooling. Setting your system charge should be done at high condenser temperature conditions. If you don't want to mess with cap tube length, make sure you have at least a few degrees of subcooling, and that the evaporator is not flooding. I have a question: what is the silver bell-shaped thing in parallel with the cap tube? I'm envisioning it being a CPEV. If so, it can prevent freezing your evaporator BPHE, but you will need a suction line (slobber box) accumulator to keep from flooding your compressor. Your 270V compressor should run just fine off 240V line current, but starting torque will be somewhat limited. A 2 or 3 minute short cycle timer box should be used to let pressure equalized between run cycles. That way, you won't have problems with the compressor stalling and drawing LRA current due to insufficient starting torque. In any case, a hard start kit will smooth the starting spike and provide a big jolt to kickstart the compressor if you need it. As for reversing the cycle, I myself would accomplish this on the water side of the two heat exchangers, rather than reversing the flow of refrigerant. Those HX's run much more efficiently, with higher delta T, when they are plumbed in counterflow. Reversing the refrigerant flow means that unless you also reverse the water flow, the unit will run less efficiently in one mode than the other. Also, reversing the water flow requires less robust methods and components. Whatever you do, make certain the evaporator HX can never freeze! Brazed plate HX's are very intolerant of Freezing conditions: they will split open like a tuna can in no time and spew their contents. Be sure to use antifreeze, and include some sort of frost sensing thermostat with flow sensing and compressor cutout control to eliminate all doubt. Other ecorenovators have been unpleasantly surprised by this event.