txv vs. pistons

[coco]

what are the differences between how a piston or txv modulates refrigerant flow? what are the pros and cons of both ~~just curious~~

[tecman]

Quick answers: piston is a fixed oriface which is perfectly optimized at only one set of operating conditions. TXV is a modulating valve that varies the expansion flow of the refrigerant by a balance of liquid line pressure and vapor line temperature. TXV provides a better metering of refrigerant as conditions (temperatures and heat load) vary.

TXV: more complex, can fail due to a number of reasons, better load matching, thus higher potential SEER

Piston: Simple, cheap, virtually no failures other than clogging, less than optimal mereting in varying conditions.

paul

[Mr Bill]

Hey, I like those pistons they work really well with a variable speed compressor.

[Panama]

And TXVs are far more forgiving of charging errors when Mr. Bill does it by pressures alone.

[beenthere]

Originally posted by Panama
And TXVs are far more forgiving of charging errors when Mr. Bill does it by pressures alone.

Hey!

He keeps a cold beer in his hand to double check his charge. LOL...