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txv too small (3 Posts)
txv too smallI was working on a carrier water source heat pump today (r410a) m#50 hq installed in april 2013.there was a certified air balance done on the unit, and airflow does not appear to be an issue.the problem is both circuits (6 ton two stage unit) are running with low suction pressure (95-100 psi) to the point where the outlet of the txv starts to ice up and the unit goes out on freeze protection. this occurs on both circuits. the charge has been removed and weighed back in to what is on the nameplate. even though this is a six ton unit with two isolated three ton circuits, the txvs are only rated at two tons each. does anyone else find this odd that you would have a six ton unit with txvs only capable of supplying four tons of refrigeration across the evaporator coil. both txvs seemed to be maintaining a good superheat (12-15 degrees) in the evaporator, it just seems that the evaporator is being starved of refrigerant, and the txvs cannot open any further
TXVWhat # are on the TXV, what brand ? Did Carrier verify the TXV #'s ? Is it a "balanced port" TXV ? What was the hiside press ? If that's low it makes the low side lower.This post was edited by an admin on August 29, 2013 7:10 AM.
N/A August 31, 2013 @ 10:44 PM
water cooled unitplease check first with carrier to verify your tx valve.I am no expert but willing to help.I read your question in a hurry, but here are a few things I wold check. If this is a water cooled 410a system sounds like you might need to check your water supply. It this a package water cooled unit? If this is please check your water volume in and out along with the temps. On a few water cooled package heat-pumps they do use two different tx valves. One for cooling and one for heating. I went too a commercial building last year to just offer some advise on why they loose so many compressors ever winter. The in house serviceman did not know that the heating tx valve and the cooling tx valves are usually two different sizes.You said you thought it was a 6 ton unit, you need about 12 -16 gallons of water an hour. I hope this helps if you need any further help just email me.
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DAVID C. BROOME