CVHE oil sump pressure

[duke of earl]

Anyone know what oil sump pressure should be relative to evaporator pressure on a R-123 machine (1987 but converted in 94)? Looking for thoughts on what could contribute to overpressurization of the sump. Thanks.

[absrbrtek]

Was the vent line size increased? Is your vent line solenoid valve working properly?

[Healey Nut]

The oil sump pressure should be the same or even slightly lower than evap pressure . is the vent line solonoid working correctly and is it installed correctly the flow should be to the sution cover NOT to the oil sump as some people think .Graham .

[duke of earl]

Vent line is 1-1/8 in. and flows from sump to suction. Sump pressure is 6" above evap pressure on two identical machines. It has been like this as long as I have been in the building (2 yrs).

[Healey Nut]

are the vent line solonoids working correctly they should close{energize}at start up the open{de_energize }after about three minutes.Did the solonoids come from Trane they are not just a regular solonoid they are OEM to Trane because of the bleed port inside them.

[duke of earl]

The solenoid valves were installed by Trane (I used to work there) when they converted the machine in 94. I believe they are the corrrect valves, the ones with the bleed port. I verified the vent line is functioning and the timing is correct.

[Healey Nut]

Is the chiller losing oil ????? Are you reading actual gauge pressure or is it from the transducer

[duke of earl]

One of the chillers is losing oil, the other is not.I'm reading gage pressure (low oil pressure gage) the gages are fairly new.

[Healey Nut]

I would be checking the gauges for accuracy . if the evap pressure was lets say 18" and the sump pressure at 12" then you better have a truck load of oil ready to put in cause its going to lose oil in a hurry ?????

[98ta]

The sump is vented to lowest pressure in the chiller, the 1st stage wheel eye!
If the vent is working properly sump pressure should easily be reduced to
below evap especially when IGV' s are closed.Are you sure these are OEM N.O. solenoids and was the Vent line size increased to 1 1/8"???

[duke of earl]

Running pressures are 18" evap and sump pressure 12".

[Healey Nut]

Think about this for a minute the evap is at 18" the sump is at 12" .the pressure at the vent line inlet to the suction cover is probably at 20-22" theres no way that chiller can not loose oil under those conditions .

[duke of earl]

It doesn't add up to me either. Both chillers are running the same pressures when in tandem. One loses oil and the other doesn't. This particular chiller ran most of the summer with no problem. I will trace out the line going to the gage tomorrow and see where it is connected.

[jayguy]

kind of a basic thought but...some of the original chillers (without vent line solenoid) had an angle valve on the suction cover, between the suction cover and the oil sump in the vent line to act as a restrictor. when these units were converted, was the angle valve removed? if it is still there, it needs to be removed, but fully opened at the very least. i would tend to believe that the vent line solenoid (or some part of it) is at issue. oil sump should be the lowest pressure in the system.

are you losing oil? or is the sump just getting pressurized and you are looking into why?

good luck.

[r404a]

Duke,
Are we getting the oil tank pressure reading on the oil charging port? Copuld we have a "Head" on that giving us a false reading? Graham,
concerning the built in orifice on the new vent valves, I remembre some valves had a stem for adjusting bleed, but I saw a new one with no stem recently. Are all of these "created equal" without regards to size of machine? What I mean is, is there just a little pilot hole in the new valve W/O any adjustment and one valve fits all?
I have heard of guys getting the wrong vent valve (N.C.) but Duke has had this machine in operation for a while, almost 2 years.

r404a

[jimactech]

did u actually check the oil pressure with your own gauges or have you relied on the panel gaugesand Tracer readings? Is it possible the line which feeds both of these is the same place you tied the oil scavenger to? Is it possible that a leak is providing a higher than actual low side pressure? This could lower the pressure differental to the oil saftey and cause nuisance trip. Are you haveing air problems with this machine? Have you checked your connections?
:rolleyes:

[duke of earl]

Duke of Oil? Hmmm sounds catchy. The oil scavenger is connected to the oil charging port on the sump(pump end). The gage line connects in the rear just above where the oil return from the eductors is connected.

[jimactech]

Duke of Oil? Hmmm sounds catchy. The oil scavenger is connected to the oil charging port on the sump(pump end). The gage line connects in the rear just above where the oil return from the eductors is connected.
Im not real fimiliar with centrifugals but after reading the info from all your post, i just thought it mite be a plausible scenareo.Good luck.

[stickerhead]

Am I reading this correct? The scavanged line off the suction cover is returned to the charging valve? That will not work. On the older CVHE's, there was a 1/2" plug on the rear of the sump. That is were we piped them to. Also, on the converted machines to R-123, we added a scavenger line to the 1/4" valve on the bottom (side) of the evaporator. I agree, the sump pressure is not correct if you guage is accurate. The sump must be lower than evaporator. This indicates a vent line solenoid problem. I have seen these valves stick closed and only vent through the small drilled orifice. If you can pressurize the chiller to 0 PSIG with hot water, you can pop the guts out of the solenoid, then see what happens.

[nun]

Has the solenoid been rebuilt? OEM gaskets used? If not there will be no bleed port on gasket.