over condensing..

[ah fai]

Hi all,

Any idea for ***** R22 system over condensing? over sizing for watercool condenser?
and what is the right pressure and temperature for the system?

thanks.

[monkey spanners]

I would think 30C would be a good minimum condensing temperature, though it depends on you system, expect a balanced port txv or an eev would cope better with low condensing temperatures.

Heres a vid i took of an air cooled system in winter time,

http://www.youtube.com/watch?v=l28FPhN3yY4

[martinw58]

i think water temp rise of between 5 or 10 degc condensing water temp

[ah fai]

ok, thanks for ur reply.

[BradC]

I recently replaced the air cooled condenser on my heat pump with a *big* bphx. It used to condense at abut 55-60C and now condenses at ~25C with ~1.5K subcooling. I had already replaced the fixed orifice with an EEV, so I don't know what the drop in pressure would have done to the original metering device. I can say that the capacity of the system has increased significantly.

I suspect as long as your metering device can cope with the reduced pressure differential, the lower you can condense, the better. My ground water loop is at about 20C so I can't really get it much lower than I am right now.

I'm waiting on a flow meter to arrive so I can properly quantify the heat being rejected into the water.

Overall, and taking into account replacing a 30W condenser fan with a 150W water pump, my net power consumption has dropped over 750W, but I'm also moving a *lot* more heat. My supply air temp has dropped from 17C to 13C on average.

[Magoo]

The ideal SDT for R22 is between +32 and +35 'C to maintain system balance. Use a water regulatig valve pressure controlled on outlet water on water cooled condenser, on larger systems have a minimum flow bypass to maintain flow to stop water pump dead heading with no flow

[BradC]

The ideal SDT for R22 is between +32 and +35 'C to maintain system balance.

Pardon my ignorance, but isn't that a bit of a handwaving generality? I'd have thought the ideal would be what the system was designed for as a minimum rather than some arbitrary value.