cellar cooler fault.

[fireblade]

I have a beermaster cellar cooler running on 134a, looking at the sight glass seems the liquid level well below the line,

in the cellar, the evaporator (very old, made by delta) seems the body and outlet pipe of the expansion valve gets iced up in approx 10 minutes after switching on, and leaving the evaporator not cold enough, this tells me that the refrigerant being too low causing pressure problem leading to the expansion valve to malfunction.. hence ice build up on the valve.

AM i right ??
as dont wanna evacuate the complete system to fit new expansion valve.

Thanks

[Professor]

I have a beermaster cellar cooler running on 134a, looking at the sight glass seems the liquid level well below the line,

in the cellar, the evaporator (very old, made by delta) seems the body and outlet pipe of the expansion valve gets iced up in approx 10 minutes after switching on, and leaving the evaporator not cold enough, this tells me that the refrigerant being too low causing pressure problem leading to the expansion valve to malfunction.. hence ice build up on the valve.

AM i right ??

as dont wanna evacuate the complete system to fit new expansion valve.

Thanks

Check the superheat setting on the valve body try turning the srcew fully in then undo 2.5 turns. Check to see if the last tubes in the evaporator are not iced up.

All this is assuming the system is fully charged.

Regards, Professor

[Brian_UK]

If you suspect that the refrigerant charge is low try a leak check of the system before you touch anything.

If it came out once it will come out again.

[monkey spanners]

Has it got a condeser fan speed controler? If its set wrong/ not fitted (fan running too quick causing low head pressure) can cause bubbles in the sight glass. Is the evaporator gummed up with mold and gunge causing low air flow. Low air flow = low load = frosty valve. Or it could just have a leak somewhere.

[fireblade]

There is no fan speed controller, or defrost heaters, a very simple circuit, i will check for leaks while the system is running then i will switch the system off, wait a while then check the sight glass for correct level, as brian and monkey say, if the charge has gone, there has to be an exit.

but on the whole do expansion valves need setting regulary if there is no other fault with the circuit ??

thanks all.

fireblade

[Toosh]

Hi It seems to me you have problem of starvation to thr TX valve, if I were you check back wards from the TX valve have you checked to see if the Compressor is pumping ie. broken valve reeds. Only a thought

Regards Toosh

[fireblade]

Thanks tosh..
before the tx valve there is a solenoid valve, which is energised, i have to do a spot heat check, to ensure the valve is operating, and the temp is the same both sides if the soleniod valve,if so, then its got to be low charge, hoping its not the valves in the comp !!

thanks
fireblade

[fazzamouse]

try putting your gauges on,this normally helps

[eddiebee]

Ill have a crack at this one, why not.

From what you've said sounds like an old pump down system. The solenoid should be open. Wouldn't expect a compressor problem, no compression means no change of state and no duty from the gas - clearly if you get frost after the TEV you are getting compression and subcooling. I'd agree that it sounds like a starvation problem.

My advice would be clear the evaporator of frost, stick the gauges on and check the superheat. If it's very high this would indicate an undercharge, possibly due to gas loss. You should never need to change the TEV setting really, assuming it was set up correctly, the whole point is that it's designed to maintain a constant level of superheat through the evaporator.

Although if you like you could try winding it out to flood the evaporator. If you still get the frost, recover and check for leaks, start with the most obvious things - flared joints etc.

hope this helps

[taz24]

Wouldn't expect a compressor problem, no compression means no change of state and no duty from the gas - clearly if you get frost after the TEV you are getting compression and subcooling. I'd agree that it sounds like a starvation problem.

I don't know what the problem is with out actualy fitting gauges and seeing it run.
Your symptoms do point to lack of refrigerant though.

But as for the comp sugestion it is feasable that the comp could have valve problems.
The comp runs but gas passes back from the high side to low increasing the back pressure and reducing the discharge pressure.
The symptons then become the same as the ones you have.

taz.

[Brian_UK]

There is no fan speed controller, or defrost heaters, a very simple circuit, i will check for leaks while the system is running then i will switch the system off, wait a while then check the sight glass for correct level,

I'm a little worried here, are you using the sight glass as a liquid level indicator when the system is switched off?

[so-cold]

have you tried changing the drier .i had a problem like this a few years ago ,the drier was full of carbon ,and as soon as i replaced drier problem solved

[paul_h]

Yeah a blockage in the liquid line causes similar symptoms to a system short of refrigerant if just looking at a sightglass or pressures. Both give you a low sightglass and low suction pressure and discharge pressure.
But normally you can find a temperature difference across a blockage, if it's a blocked drier, the drier outlet temperature would be slightly cooler than the inlet.

Not to mention subcooling of the liquid line, the liquid temp after the condenser in a system short of refrigerant would be way hotter compared to the temp read off your gauge/PT chart than system with a blockage due to the backed up liquid in the coil.