View Full Version : Original compressor replaced with smaller size

16-05-2017, 01:35 AM
Hello, I am currently working on a small island in the middle of the pacific with very limited resources.

My question is this, would it be ok to, let say, replace a 38000 BTUH R410a compressor with and smaller 32000 BTUH compressor of similar characteristics and voltage. I am an HVAC professional and have always just replaced compressors with the correct size when needed. In my mind this should work ok under low load conditions but fail to work correctly when things get hot.

I know this is highly unadvisable but as I said, I'm in the middle of the pacific with a 1 month delivery time minimum! The poor chef in the kitchen is literally melting and looking for any answer.

Your thoughts and concerns would be most appreciated by Pedro in the kitchen.

16-05-2017, 04:08 AM
It will struggle, but better than nothing at all. Limp you through till you get the correct compressor delivered?

The Viking
16-05-2017, 01:20 PM
As Goober said, it will struggle.
Depending on your expansion/metering device it will struggle in different ways.
- If you got a capillary or fixed orifice device then your smaller compressor will not be able to reach the target evaporator temperature, the superheat will become high and you might overheat the compressor.
- If you got an expansion valve that can cope with the varied capacity the superheat should be regulated but the system will not cope with the same load as it did before.
In both cases, depending on pipework and layout, oil return might also be an issue.

What's the worst that could happen? The system still doesn't work but you gained some experience...

16-05-2017, 03:18 PM
With the potentially high evaporator load that will be present when the kitchen is busy and given the 16% capacity reduction, you may need to reduce the quantity of the refrigerant slightly to prevent excessive pressures etc. You will probably have to nurse-made the system until you get the trim charge correct.

16-05-2017, 03:59 PM
I thank you all for your quick advice. You have confirmed and added to my own thoughts. I manly needed to know what to warn the customer about so they would be educated on the problems with this set up. I think we are going to try it for now at least and see how it goes.

This forum has been a great resource for me over the years. I just have never posted since I've always been around knowledgeable people that answered all my questions while I worked in Canada. I find myself now, all alone in foreign land and this forum to be my savior. Thank you all again!!