Waeco coolmatic upgrade or not?

[razamataz]

Hi

I have a perfect working order Waeco coolmatic fridge.
during the refit i have made many improvements to various systems including adding a fan to the compressor unit that was installed in a cupboard with no ventilation and heated all the alcohol cupboard above it - now all the alcohol and more important the compressor is cool to the touch

but...i also added some insulation tube from the compressor all the way to the vaporizer/fridge box directly on the copper tubing

going on the same rational of domestic AC unit that have one cold line and one hot line, and every degree counts - BUT strangely the coolmatic only has one line from the compressor to the vaporizer\fridge box

where is the other line? the copper tube is neither warm or cool to the touch, did i do right by insulating it?
is it line inside a line? does that even make sense in terms of energy efficiency?

can someone with knowledge of this fridge unit extrapolate how this unit works?

[Bowdrie]

Originally Posted by razamataz

i also added some insulation tube from the compressor all the way to the vaporizer/fridge box directly on the copper tubing

going on the same rational of domestic AC unit that have one cold line and one hot line, and every degree counts - BUT strangely the coolmatic only has one line from the compressor to the vaporizer\fridge box

where is the other line? the copper tube is neither warm or cool to the touch, did i do right by insulating it?
is it line inside a line? does that even make sense in terms of energy efficiency?

can someone with knowledge of this fridge unit extrapolate how this unit works?

If you look at the condensing unit you will see that there are indeed two tubes connected to it, the same at the evaporator.
When the length of run allows, it is common to run a tube-in-a-tube between the two units.
Thermodynamically, (too big a word,) it allows the suction line, (the outer tube,) to function as a sub-cooler for the liquid line.
This serves a couple of functions, it removes additional heat from the liquid line, helping to prevent "change of state" gas bubbles in the liquid line in hot environments, also helping to lower the heat load on the condenser, and the suction line, (by absorbing some heat from the liquid line,) reduces the tendency of the suction line to "sweat" and drip water.
It also helps raise the pressure in the suction line a little bit and this helps promote good oil return back to the compressor.
Your adding insulation around the line does no harm, it actually allows the system to operate in a more temperature stable situation and is commonly added to many units by the installer.
No harm, no foul.

[razamataz]

Thanks Bowdrie

the compressor unit indeed has 2 lines but...one goes out from compressor to evaporator and one just loops from compressor to the condensor/radiator grill

single line goes behind the wall to fridge box - where it might split into 2 behind cold plate in an inaccessible spot to see

for thermodynamic i thought the 2 lines should be seperated as you lose efficiency no? the hot retuning gas warms the incoming cold liquid?

but if you say insulating the single line helps somewhat i will leave the insulation i did

[goeasy123]

You might also try this....


I replaced the temperature sensor with one of these. This allowed me to play around with the hysterisis and cycle time. It cut max current draw in 1/2 and consumption by 40%.



https://www.aliexpress.com/item/1005...Cquery_from%3A

[razamataz]

[QUOTE=goeasy123;3882106]You might also try this....


I replaced the temperature sensor with one of these. This allowed me to play around with the hysterisis and cycle time. It cut max current draw in 1/2 and consumption by 40%.


wow thanks! I used to install those many yrs ago in freezer rooms and never had the thought of putting one in for the boat fridge!
so I basically give the controller +- and then the disconnecting the wires that come from the inside fridge knob controller from the compressor electrical board and connecting the relay +- from the new controller
right? the compressor board shows 2 wires marked T and C and the wire goes all the way to the fridge
is the compressor reading temp or has on\off relay input from the fridge knob?

[goeasy123]

[QUOTE=razamataz;3884518]

Originally Posted by goeasy123

You might also try this....


I replaced the temperature sensor with one of these. This allowed me to play around with the hysterisis and cycle time. It cut max current draw in 1/2 and consumption by 40%.


wow thanks! I used to install those many yrs ago in freezer rooms and never had the thought of putting one in for the boat fridge!
so I basically give the controller +- and then the disconnecting the wires that come from the inside fridge knob controller from the compressor electrical board and connecting the relay +- from the new controller
right? the compressor board shows 2 wires marked T and C and the wire goes all the way to the fridge
is the compressor reading temp or has on\off relay input from the fridge knob?

Yes. The compressor just sees on/off from the thermostat. The only other function the old thermostat has is some fixed range hysterisis. With the new controller you can vary that. With this you can adjust the cycle time. I've taped the sensor in the part of the fridge I want to be warmest (where we keep stuff like lettus). I set the temperature here so that the freezer box (which is our fridge design) gets to below zero and then adjust the hysterisis so that it very gets above -2C.


The controller tells you the actual temperature at the sensor and I have another cheapy digital temp guage I used temporarily in the freezer box for set up.