Hot Gas Bypass Chiller Setup - Thoughts?

[MpSystems]

I am currently putting together a 1 1/2ton chiller unit. The design of this system encorporates a liquid line, hot gas solenoid, heat exchanger and txv. The point of the hot gas bypass is to level out the temp of the fluid being cooled through the heat exchanger as well as prevent the heat exchanger from freezing up. I'm having a problem where even when I open the hot gas bypass valve going into the inlet of the evaporator, the temp is still dropping. The txv is overcoming the hot gas coming in and still maintaining a temp drop. Any comments?

[simon@parker]

dunham bush made a chiller set with that fitted bout 30yrs old worked on it had 3 D6 carrier compressors with capacity control think only 2 of the compressors were supposed to run and 3 rd came in on heavy load there were 4 of theses in a plant room took me 3 months to get them set back to original running configeration units were on R22 set unit to run set up TEV first then i set head pressure control R22 ran it 220 to 240 hot gas was o a solanoid and then went through a capacity control evap pressure regulator the solanoid opened on a suction pressure drop when i finally had it set rite i had water inlet of 16 out of 10 deg C without hot gas it dropped to 6 water flow is important as is load all 4 of my units did one ring no buffer tanks it was a simple system but had been poorly maintained by dodgy engineers good luck with it :)

[TXiceman]

Sounds like the controls are not set up properly, the valves sized incorrectly or just the plain wrong controls.

If the leaving product temperature is critical, you may want to add a temperature compensated evaporator pressure valve along with the externally equalized hot gs control valve. Sporlan will tell you that this will not work, but I have used it many times. Contact Parker - R/S and get some help from them.

[RANGER1]

Normally I would have thought this set up has a compressor with unloading.
When compressor is fully unloaded & suction pressure drops slightly past this point then
hot gas false load valve comes on.
This stops unit from cycling if false load valve etc is sized right.
it also should be to prevent water temp getting to low.