txv

[hnil]

Could someone help me explain the difference between none-bleeding expansion valve and bleeding expansion valve and how are they connected differently?

Thanks

[kerndt]

A none bleed expansion valve is a valve that will close completely, not to allowing the systems pressures to equalize. This helps prevent flooding the evaporator on the off cycle.

A bleeding expansion valve does allow pressure equalization on the off cycle, were evaporator flooding is not a problem, and allows for a lower torque compressor for starting.

Both valves would be connected the same. Only the internal parts are differant.

These designs are for differant system applications. Changing valves on a system could cause the compressor to slug liquid, or a compressor starting problem.

Why do you ask?

[hnil]

thanks,

I often got asked and don't know

[fat eddy]

Some non bleed applicatins will use the TXV as a solenoid because it will provide 100% shut off and in place of using a large solenoid, You can use a small one on the externally equalizer line to act as a pilot duty solenoid and slam the valve shut.

[Shophound]

A non-bleed valve will do as the others say; i.e. not allow system equalization to prevent floodback to the compressor upon system startup.

It is also thought that a system that does not equalize after shutdown will spend less time coming back into its nominal operating parameters after it restarts. IOW the compressor isn't spending a lot of time pulling the evap back down to design saturated vapor temp/pressure since the pressure in the evap at startup is more or less already there.

Non-bleed TXV's will require a start cap and potential relay on a single phase compressor.