"Toby" wrote in message
...
On 07/04/2013 18:24, Mr Pounder wrote:
"Toby" wrote in message
...



How did you recharge it?


I bought the following things

Manifold gauge set
http://www.ebay.co.uk/itm/290496320732

Small cylinder of R600a refrigerant
http://www.ebay.co.uk/itm/380597193357

Valve for the cylinder
http://www.ebay.co.uk/itm/110982392239

I already had a 0-500g set of scales like this
http://www.ebay.co.uk/itm/181112007479

The freezer already had two service valves fitted, so I didn't need to fit
any - if they were not there, I would have bought a line tap like this
http://www.ebay.co.uk/itm/130577043065 and fitted it to the suction line
(that is marked on the compressor usually, if not, it is the thicker pipe
that comes from inside the freezer, not the one that goes to the condenser
on the back).

I connected the blue hose to the blue side of the manifold, and the other
end of the blue hose to the the suction side of the compressor in the
freezer.

I then connected the red hose to the the second tap of the middle
connection on the manifold (not the red side of the manifold), and the
other end to free air (R600a is flammable, so it needs to vent outside)

The yellow hose to the bottom connector of the middle port of the
manifold, and the other end the the valve on top of the R600a cylinder
with the cylinder valve off.

I then opened the blue tap to let out the gas that was in the freezer (out
of the red hose), when it stopped hissing I let a small amount of R600a
out of the cylinder to purge the yellow hose, then connected the free blue
hose to the vacuum pump.

Then I turned on the vacuum pump (old compressor) and opened the blue
valve, and left it sucking for about 30 minutes.

With the vacuum pump still running I turned off the blue valve and then
disconnected the red hose (it connects to a self closing valve on the
manifold)

This then left me with all the connected hoses and the freezer pipework
under vacuum. I left it like this for about 30 minutes, and it was still
showing the same vacuum, so if there is a leak, it isn't a big one!

I placed the R600a cylinder on the scales, and hung the manifold in a way
so the cylinder wasn't wanting to tip over, and the weight of the hose was
constant

With the cylinder on the scales, I then opened the valve on the cylinder
and zeroed the scales.

I then turned the freezer on, and when I heard the compressor kick in, I
opened the blue valve to let the compressor pump the gas into the freezer.

The data plate states it takes 54g of R600a, so I watched as the scales
slowly climbed up - when it got to about 32g, the damn scales auto-powered
off, so I quickly turned the blue valve off, (I also connected the red
hose to the red side of the manifold and the other end to the high side of
the compressor - this wasn't really necessary, I just wanted to see what
the pressure was showing on the high side when the compressor was running,
I also warmed the cylinder up a bit, as the rate of flow had been trailing
off because the cylinder was getting really cold) I then reset the scales,
and carried on.
When I had put 54g in, I shut the blue valve.

I then put a bit more in (5g), to allow for some refrigerant in the hoses,
and I had read about the suction side should read around 0 when it is
full, and as it was still pulling a vacuum, I put some more in. I am not
sure about this part, hence the question, and figured I could just let
some out, plus I suspect it has a very slow leak. Total that left the
cylinder was 60g.



I am obviously not a refrigeration engineer (hence the original question!)
so I may not have done this correctly, but after reading up on it for
quite a bit, I think I did a fair job, a proper vac pump would have been
ideal, but I figured the system should be pretty clean as it was still
under some pressure, and I figured the old freezer compressor I had would
do in this case. Ideally the filter/dryer should be replaced, but I don't
have any brazing or lokring tools to do this (yet!) - The Lokring stuff
looks really easy to use, but damn expensive compared to brazing rods and
a mapp gas torch. And I would want to purge the lot with nitrogen if I
welded anything on it too, and I don't have any nitrogen either...

If you use an old compressor as a vac pump, the output tends to spit oil,
I found this out when I fired it up on my desk inside, which wasn't the
best place to do spray oil everywhere in hindsight (the fact I had moved
the compressor 5 minutes before probably increased the amount it spat out
too), so to overcome this, I connected a few meters of clear pipe to the
output, and scrunched up a tissue and tied it to the end this seems to
have done the trick The oil sprays up the pipe to start with (I kept
almost all of it vertical), but as the other end is then under vacuum,
quite quickly the oil just ran back down into the compressor as there
isn't any air blowing out the port.

All I can say is VERY well done.