Can't get any sub-cooling

[lexscripta]

Hi Guys,

A 3/4 hp 404A medium temp walkin system rated at about 7500 BTU, @ 90 Ambient.

So, I realized that my actual ambient is rarely less than 100 degrees, and often hovers in the 110 -115 range. Looking at the charts reduces capacity down to around 3500 BTU at that temp.

Lots of bubbles in the site glass = NO subcooling.

Anyhow the thing was adjusted by someone by reducing the refrigerant, 'cuz if you charge it up, we see in excess of 375 PSI liquid line pressure. On occasion the HP Cut out trips.

To keep SOME cooling, its apparent that the refrigerant was bled off on purpose because of the High ambient. However, low refrigerant means high compressor temps and poor oil flow. Consequestly, the compressor trips off once in awhile.

Can't install a condenser outside, no place for AC. So, heres the question. Anyone have any ideas on how to go about installing a subcooler? Or maybe the best question is who has something like that for a system this small? Has anyone put in a Sub Cooler of their own making? I was thinking along the lines of something like the variety seen in Manitowoc Ice machines, but that takes a lot of water.

So there ya go. I didn't add too much in the way of measurements because with a reduced charge, SH is going to be High anyhow, and its obvious there's no SC.

[Brian_UK]

Is there anything that you can do to increase the airflow over the condenser?

Can you increase the size of the condenser or fit a second coil?

[dan247]

How bout shade for the unit that's 10-15 degrees cooler right there. And change the condensor fan motor with a higher rpm. Keep them coils clean and make sure there is enough charge for winter time.

[Toosh]

Hi Lex, Is there no room to install an exhaust fan

Norm

[chilled kiwi]

You either need to remove the excess heat from the condensr area, or increase the size of the condenser. I would look at doubling the size at least. The only other thing is a CPR valve to maintain a constant refrigeration effect. You will still only get the 3500btus as the condenser is the limiting factor. If your client doesn't want to spend any money, try winding is the suction valve to maintain a low condensing pressure, or reduce the airflow over the evaporater. Keep in mind these are only patches, not cures.

[desA]

What about a pre-cooler for the air, using the evaporation principle?

Basically a water pad which raises humidity, but lowers temp into condenser coil? If memory serves, BAC do offer something of this sort. There will be others.

[chancie owens]

you either gotta cool the air in the room or go with a water coax, it may increase the water bill but the equipment will do what it needs to.