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.
--
Toby...
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