R600a Fridge

[LeighC]

Hello all, I am after a bit of info on a domestic fridge Skandiluxe (Similar to Vestfrost) please?
I have fitted a new compressor & have weighed in the 35grams (on ID plate) of R600a (Isobutane) & have very high Superheat & a warm suction line when the cabinet is at its design temp of + 2°C
Test figures are-

Ambient temp 30°C Humidity 50% Compressor is only drawing 170mA which is well under the Danfoss design chart.


Evap. cabinet temp 0°C (32°F)
Low side saturation temp -19°C (-26kPa) (-7.6"hg)
Suction line temp of + 31°C (88°F)
SH 50 °K (90°R)

Condenser temp 44 °C (111°F)(outside of cabinet, inside wall condenser)
High side saturation temp. 46°C (115°F) (525kPa) ( 76psig)
Liquid line temp 43°C (109°F)
SC 3°K (5.4°R)

I am worried that the compressor may run too hot when the hot weather comes with the high SH? Can I get any expert opinions please? Do I need to add more charge?
PS it is very hard to weigh in 35grams with a STD 1/4" hose hanging on a small R600a can.
PS This section of fridge is not the freezer part. (it has completely dual systems)

Thanks in advance for your help. Leigh

[sacoolman]

Hi,try adding in a little more gas. Did you fit the same type of compressor?

[LeighC]

Thanks for your reply Sacoolman,
The new compressor was supplied by the fridge dealer for free (sort of extended warranty-customer relations) to help us out & sat around for a while, It is bit smaller (3.86cc) Danfoss TLES-4KK-2 R600a against the original VOE HYV44AA 0038 R600a (4.38cc)
I did add a few more wiffs of gas one day & it seemed to play around with the thermostat badly.
I took the suction down to -24°C (-11°F) -41kPa (-12"hg) (-0.4bar) as suggested by some old posters on a search on this forum & the suction into the compressor frosted badly & the thermostat didn't cycle properly, the cabinet went down to about -4° after an hour even with the thermostat set on low (No. 1 on the dial)
Seems very hard to get the charge & SH correct at cabinet design temp (operating) about 2°C.
This fridge appears to be too efficient & working too good.
Do we set a fridge (cooler only) different as apposed to a freezer & fridge combined?
Sorry my experience has been mainly automotive AC.
Thanks - Leigh

[seadanzig]

All the system I have looked at the comps always run hot.
If you dont think the capilary has any blockage and you changed
the drier add a few more grams and let it be.

[Adeelismail]

Hi
U have same r600a type compressor

[LeighC]

Haven't had time to get back to the fridge yet, but I will play around with charge a bit, I think the humidity may of been playing around with the frost on the suction line, & I may lag the pipe a bit.
Yes it is a R600a compressor but the one that the company supplied under a belated warranty claim for free is 13.5% smaller in capacity & after reading about capillary tubes & an inefficient compressor it seems as if the capillary may now need to be shorter or smaller to have the balance correct.
Thanks for your help - Leigh