Meakoda
07-07-2010, 04:08 AM
Hello everyone,
I had an odd issues that I ran into the other day that I was looking for some insight on. A major chain customer has a W-I-F that they have had for over 3 years. I was on site servicing another piece of equipment when he mentioned issues with ice development on the TXV side of the evap. coils of his freezer.
When I inspected I saw only 1 huge block of ice encompassing the entire left panel section with none on the evaporator. The customer states he has not had any cooling issues with this freezer although I suspected possible high recovery times.
After removing the ice, found evaporator superheat extremely high (37) w/ box temp. of approx. (+20 F). Condenser coils that were 90% clogged on roof and very low pressures of 19/225-230 404a w/ ambients of approx (+78 F) after coils were cleaned. Subcooling of (6). Compressor Superheat was approx (56). NOTE: Sight glass full
Also I found out that the refrigeration system was undersized for the Box size.
Box Size = 560 cu Ft.
Evap= 7500 BTU
Cond = 1 1/2 HP
Spoke with a heat craft rep. and he said for the Box size that I should be running approx.
Evap= 9000 to 9600 BTU
Cond = 2 1/2 to 3 HP
Keep in mind, according to the owner, he has not had any service calls on this unit apparently in 3 years which I find hard to believe.
I ended up adjusting the TXV to lower both my super heats values as well as increased my over all pressures. I also, understand you cannot get a correct superheat value till the box is close to temperature due to the TXV throttling. NOTE: Bulb mounted correctly.
After I was done adjusting the TXV, w/ box temp at approx (+7 F) and ambient condenser temps of (80-82 F) I increased my pressures to 21/250 w/ compressor superheat of approx (30) and evap superheat of approx (10), Subcooling (10). I did not have further time to watch the unit as I was sent off on an emergency, I am under the assumption that the super heat values will lower a bit more as it comes down in temperature some more.
I do plan on returning throughout the week for a follow up check.
My questions are.....
1) Did I do the right thing?
2) Was the ice build up from the distribution lines a bi-product of the undersized refrigeration unit?
3) How the heck has he not had a service call from the unit being undersized?:confused:
Thanks in advance for any helpful comments.
-Meakoda
I had an odd issues that I ran into the other day that I was looking for some insight on. A major chain customer has a W-I-F that they have had for over 3 years. I was on site servicing another piece of equipment when he mentioned issues with ice development on the TXV side of the evap. coils of his freezer.
When I inspected I saw only 1 huge block of ice encompassing the entire left panel section with none on the evaporator. The customer states he has not had any cooling issues with this freezer although I suspected possible high recovery times.
After removing the ice, found evaporator superheat extremely high (37) w/ box temp. of approx. (+20 F). Condenser coils that were 90% clogged on roof and very low pressures of 19/225-230 404a w/ ambients of approx (+78 F) after coils were cleaned. Subcooling of (6). Compressor Superheat was approx (56). NOTE: Sight glass full
Also I found out that the refrigeration system was undersized for the Box size.
Box Size = 560 cu Ft.
Evap= 7500 BTU
Cond = 1 1/2 HP
Spoke with a heat craft rep. and he said for the Box size that I should be running approx.
Evap= 9000 to 9600 BTU
Cond = 2 1/2 to 3 HP
Keep in mind, according to the owner, he has not had any service calls on this unit apparently in 3 years which I find hard to believe.
I ended up adjusting the TXV to lower both my super heats values as well as increased my over all pressures. I also, understand you cannot get a correct superheat value till the box is close to temperature due to the TXV throttling. NOTE: Bulb mounted correctly.
After I was done adjusting the TXV, w/ box temp at approx (+7 F) and ambient condenser temps of (80-82 F) I increased my pressures to 21/250 w/ compressor superheat of approx (30) and evap superheat of approx (10), Subcooling (10). I did not have further time to watch the unit as I was sent off on an emergency, I am under the assumption that the super heat values will lower a bit more as it comes down in temperature some more.
I do plan on returning throughout the week for a follow up check.
My questions are.....
1) Did I do the right thing?
2) Was the ice build up from the distribution lines a bi-product of the undersized refrigeration unit?
3) How the heck has he not had a service call from the unit being undersized?:confused:
Thanks in advance for any helpful comments.
-Meakoda