TXV Valve

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TXV Valve

Postby Dxrocaa4 » Tue May 01, 2012 12:54 pm

Hi guys! I'm a HVAC newby----Every now & then I run in to a unit where I can't tell if it has a fixed metering device or a TXV valve---What's the quickest & best way tp determine if the unit is fixed metering or TXV---I was trained to charge either on sub-cool for TXV-----or superheat for Fixed metering device----But this HVAC pro at work said he charges everything TXV & fixed metering via superheat----he said superheat is more efficient-----So what's the truth here?
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- TXV Valve

Postby Freon » Wed May 02, 2012 11:25 am

Quickest way is to look for a thin (1/16 to 1/8") tubing going from the TXV on the high side, close to the evaporator coil, to a bulb (2"x 3/3") attached to the suction side. If it's a fixed orifice, you'll only see the high side enter the evaporator coil without anything strange in the way.

Time is money. The more you measure the more time it takes. Yes, both superheat and sub-cooling would be best. But if the manual for the condenser only has superheat values then that's what you go by. Always get the manufacturer's specs to use as a guide for your measurements.
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- TXV Valve

Postby heatseeker » Fri May 04, 2012 8:28 am

Some companys instal txv and bulb inside of coil box so you can't see it. In that case you would have to rely on suction pressure fluctuations.
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