setting up txv

[frankman]

i have a split system heat pump (american) 3 ton r410a. ive installed a txv in place of the piston type metering device. can someone give me some advice on the best way to go about proper adjustment of set screw. should i start with set screw turned all way in clockwise? can someone give me step by step instructions for this. any help will be greatly appreciated.

[monkey spanners]

Hi Frankman,

Are you refering to the set screw on the txv itself?
If so there is generally no need to adjust it, it is there for the factory to adjust the valve before shipment. On very rare occasions it may need a tiny adjustment. I have never had to adjust one on a new valve with the correct orifice installed.

Ensure the bulb is installed correctly on clean pipe and insulated well and that the equalising line if fitted is also piped correctly.

[frankman]

the orifice comes out if adding external txv right?

[monkey spanners]

Yes the fixed orifice or piston as i think its know in the States is replaced by the txv.
(The orifice i was refering to in my first reply is the one that goes in some makes of txv such as danfoss to size them for various system, they might also be called a cartridge or cage).

Is this a cooling only or heat pump system? Because things get complicated in a heat pump with the need for check valves etc if my understanding is correct, we don't get those design of systems here in the UK, its mostly mini splits which designed differently.

Jon