Refrigeration 101

[Deniver45]

Gary,

When you say "Generally speaking, a freezer should have 6-8F/3.5-4.5K superheat, a cooler should have 8-10F/4.5-5.5K superheat, and an A/C should have 12-16F/6.5-9K superheat."

At what abient temp are we talking here?

75 degree's?

[Gary]

Gary,

When you say "Generally speaking, a freezer should have 6-8F/3.5-4.5K superheat, a cooler should have 8-10F/4.5-5.5K superheat, and an A/C should have 12-16F/6.5-9K superheat."

At what abient temp are we talking here?

75 degree's?

Normally, the ambient temp would have relatively little effect on the superheat.

[desA]

Normally, the ambient temp would have relatively little effect on the superheat.

In my heat-pump trials, I have observed an influence on evaporator SH, due to ambient air temperature movements.

If Ta,in falls during the range of test, SH will roll down a little more than if Ta,in is constant.

If Ta,in rises during the range of test, SH can often end up being almost constant over the test duration.

The influence can be in the range of ~ 1-3K, depending on the operating SH of the machine.

[Gary]

In my heat-pump trials, I have observed an influence on evaporator SH, due to ambient air temperature movements.

If Ta,in falls during the range of test, SH will roll down a little more than if Ta,in is constant.

If Ta,in rises during the range of test, SH can often end up being almost constant over the test duration.

The influence can be in the range of ~ 1-3K, depending on the operating SH of the machine.

In your heat pumps, the ambient air would be the air entering the evaporator. As I interpreted the posters question, I believe he was referring to the air entering the condenser.

[desA]

Gary,

When you say "Generally speaking, a freezer should have 6-8F/3.5-4.5K superheat, a cooler should have 8-10F/4.5-5.5K superheat, and an A/C should have 12-16F/6.5-9K superheat."

At what abient temp are we talking here?

75 degree's?

This is the post I was referring to, Gary. There is a mix of applications & conditions here.

It could be useful to split the air-breathing evaps from the closed-space evaps, in regards to the SH question - it will be less confusing.

[Gary]

This is the post I was referring to, Gary. There is a mix of applications & conditions here.

It could be useful to split the air-breathing evaps from the closed-space evaps, in regards to the SH question - it will be less confusing.

I agree... both the question and the answer could have been more specific.