Have just built a prototype compressor unit waterchiller to handle 900W load and are now up and running what seem to be quite ok, well the water at least get about the wanted temperature anyway.

Although some measurements feels like they are a little to high and would be very happy for some help in this because im using only a capillary tube for this nothing else since the load will be quite constant but i dont know how to fine tune these systems if needed.


The water out from the heat exchanger needs to be under 20C so i just guesstimated the evap needed to be around -10C based on the heatexchanger size and how it its built internally, so thats what the captube is based on and so far so good. According to Dancap which i used for this i needed a captube that was 1.4 mm inner and 2.06 meter long.

The only captube i had in the whole house was 1 mm that was 3.96 meter long but paralleling two 1 mm would be equal to one tube that was 1.41 mm which was fine with me and is what i have on the system now but i dont know if its to long or to short for an optimal system with this load and so on.

So here are some measurements on what i think you guys might need. This is when the system had been running for only about 35 min since the temp in the room started to rise to much (small room) for my own comfort and the water started to be to cold (13C since it will starting to freeze up in the exchanger at about this temp) so i shut it off but minutes before so did i took these measurements:


Condensor Air
In: ~26C
Out: 37.3C

Condensor temperatures
In: 86C (this feels waaay to high?)
Out: 40.2C

Evaporator/Heatexchanger
Casing: ~ -2C (some distance from captube inlet)
Outlet: 13C (~10cm from evap but this tube between the comp and evap is very short only about 20cm (8") if that might matter

Pressure
Highside right after condenser: 13.8bar (once again feels high?)
Suction: 2.5bar

Gas used
BBQ propane (only gas i can get hold on, i use a big filter/drier though)

Compressor
SC15D HST/HBP


If any other info needed just give it a shout.
　

　
The captube i use is the ONLY captube i have and i cant get any similar one, or any other at all for that sake, so i dont dare touch it until i really really know so guesses about the captube length or so arent really what i need due to this unless its a good qualified one.

The pressure in the system when its at room temp (21C) is 7.8 bar and that to feels like its to much gas in it but i need to have this much to get the watertemp i needed. The evap obviously isnt filled enough to act fully as it could but due to the amount of gas now as for before so will the watertemp even be lower then needed after some time. That it self is not a problem in one way because the comp will later on shut down with a controller when the right water temp has been reached.

Before i got more gas in the system the water temp out was only 20 – 18.8C which was little too high but the pressure was lower with about what i feel more normal 11 - 12 Bar high and around 1.5 - 2 Bar low if i recall right. When i put in more gas the pressure went of course up to the pressures stated before and the evap was at about the same temp. When i then put more gas in it the water now went down to 13 C although it took several minutes but down to 18C happened much faster now and it kept going.


As for the water temp the system is ok but im worried about some measurement since im not that into captube designs. So should i mess with the captube and/or lower the pressure a little or do anything else or perhaps do nothing?

The evap needs quite a lot to be filled since its quite big internally but this of course means a higher pressure and thus higher highside pressure which cant be good over a certain threshold which i dont know so i dont know whats ok and not. I could leave it but i dont like these high temperatures and i want the system to live a good life by many reasons.

Any help would be highly appreciated about if these measurements are ok or not so i can go forward with this.