Evaporator to air TD

[kfjoe]

Hi all

Could anyone advise me on what a low evapotaor to air TD would indicate please ?

I have a system which in normal running has an average 10 degc TD between evaportaor sat temp and air return , but on this paticular system i am getting only 5 degc TD,
I am wondering if a compressor not running at full capacity due to broken valves etc would cause this ?

any help much appreciated

thankyou

[marc5180]

If there is a lack of airflow across the evaporator then your Delta T will be large.

A fouled evaporator causes an abnormally small Delta T for the air.

[marc5180]

Sorry i read your post wrong there.

Could you provide the figures you used to work out the low TD if you have them?
Including superheat and subcoolinng

[nike123]

Are you sure in your measurements?

[D.D.KORANNE]

An evp td has a bearing on the humidity in the cold room & it varies with product . High td means low rh & viceversa

[kfjoe]

Thanks guys

I am basically asking if anything can change the TD of the Evap , ie inop fan , blockage , compressor not pumping to efficency etc.
or is this fixed ?


Thanks

[powell]

Hi all

Could anyone advise me on what a low evapotaor to air TD would indicate please ?

I have a system which in normal running has an average 10 degc TD between evaportaor sat temp and air return , but on this paticular system i am getting only 5 degc TD,
I am wondering if a compressor not running at full capacity due to broken valves etc would cause this ?

any help much appreciated

thankyou

A 5 degree TD is normally too low. A high humidity box such as a flower cooler runs around a 8 TD.

Did this system work ok in the past?

You need to note all the pertinent information such as pressures, temperatures and amperage to determine the cause.

I would suspect loss of capacity due to a compressor problem, TEV problem, a restriction, low on refrigerant or maybe a dirty evap or fan motor problems.

Get all the data and work from it.

Here's a link to some troubleshooting guidelines that might help you.

http://www.hvacrinfo.com/system_trouble.htm

[nike123]

Thanks guys

I am basically asking if anything can change the TD of the Evap , ie inop fan , blockage , compressor not pumping to efficency etc.
or is this fixed ?


Thanks

I would say that is determined by evaporator construction and materials. Since both are unchanged and air flow is probably same or lower as first day, TD could only be higher.
Are you 100% sure that your measurements and calculations is right.
Calibrate your instruments or use calibrated.