Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?

Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)

Thanks for any pointers :-)

--
Toby...
Remove pants to reply

"Toby" wrote in message
...
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working properly,
(after being turned on for a while, it would lock out and alarm because it
was not getting cold enough) - it had the signs of low refrigerant, so I
bought a set of gauges, and that confirmed it was indeed extremely low,
pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a there
was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)

My question is, how do I know if there is enough refrigerant in the system
if I check it at a later date without having to wait for it to be so low
it stops cooling and alarms? I weighed in the amount it stated I needed on
the data plate, but if it does need topping up at a later date (which I
assume is likely if there is a small leak somewhere (which I will try to
find)) then how do I tell how much is in there at any given time?

Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)

Thanks for any pointers :-)

How did you recharge it?

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...
Remove pants to reply

Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?


It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. That's why you put a weighed
quantity in rather than filling to a pressure.

Tim

On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?


It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. That's why you put a weighed
quantity in rather than filling to a pressure.

Tim


I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0
when running, maybe that is the answer...


--
Toby...
Remove pants to reply

Toby wrote:
On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?


It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. That's why you put a weighed
quantity in rather than filling to a pressure.

Tim


I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

Well, I did say "obvious", not "easy". ;-)


I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0 when
running, maybe that is the answer...

Your seem to be well on your way to becoming a refrigeration expert anyway
so I suspect you know more about the subject than 99% of the folk here (me
included). ;-)

Tim

Tim+ wrote:
Toby wrote:
On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?


It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. That's why you put a weighed
quantity in rather than filling to a pressure.

Tim


I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

Well, I did say "obvious", not "easy". ;-)


I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0 when
running, maybe that is the answer...

Your seem to be well on your way to becoming a refrigeration expert anyway
so I suspect you know more about the subject than 99% of the folk here (me
included). ;-)

Tim

:-) been doing my homework! I was hoping there may be a proper
refrigeration expert lurking to fill in the gaps :-)

Also interested in a cheap leak detector for R600a and if it works on R410a
then that would be great too...


--
Toby... remove pants to reply

Toby wrote:
Tim+ wrote:
Toby wrote:
On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?


It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. That's why you put a weighed
quantity in rather than filling to a pressure.

Tim


I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

Well, I did say "obvious", not "easy". ;-)


I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0 when
running, maybe that is the answer...

Your seem to be well on your way to becoming a refrigeration expert anyway
so I suspect you know more about the subject than 99% of the folk here (me
included). ;-)

Tim

:-) been doing my homework! I was hoping there may be a proper
refrigeration expert lurking to fill in the gaps :-)

Also interested in a cheap leak detector for R600a and if it works on R410a
then that would be great too...




You can stick a bit of uv dye in the middle hose before you connect the
fill bottle.You will be able to find leaks with a uv light.

On Apr 7, 6:11*pm, Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?

Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)

Thanks for any pointers :-)

--
Toby...
Remove pants to reply

It's down to the pressure readings. I don't know the values for these
newer refrigerants.

On Apr 7, 11:40*pm, Toby wrote:
Tim+ wrote:
Toby wrote:
On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?

It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. *That's why you put a weighed
quantity in rather than filling to a pressure.

Tim

I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

Well, I did say "obvious", not "easy". ;-)

I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0 when
running, maybe that is the answer...

Your seem to be well on your way to becoming a refrigeration expert anyway
so I suspect you know more about the subject than 99% of the folk here (me
included). ;-)

Tim

:-) been doing my homework! I was hoping there may be a proper
refrigeration expert lurking to fill in the gaps :-)

Also interested in a cheap leak detector for R600a and if it works on R410a
then that would be great too...

--
Toby... remove pants to reply

In domestic refrigerators a small surplus of liquid gas remains in the
bottom of the compressor housing during operation. When this has all
leaked out there is a radical change in the gas pressures in the
system

Commercial freezers/fridges usually have a "condensing unit" that
incorporates a reservoir for liquid gas, as well as the compressor and
condenser. They sometimes have a sight glass incorporated. So it
takes longer for leaks to have any effect.
http://en.wikipedia.org/wiki/Economizer#Refrigeration

On Apr 7, 11:40*pm, Toby wrote:
Tim+ wrote:
Toby wrote:
On 07/04/2013 20:52, Tim+ wrote:
Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and alarm
because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given time?

It's obvious, just weigh the whole freezer. ;-)

Seriously, with a refrigerant that's probably part liquid, part gas, a
pressure reading will be of no use to you. *That's why you put a weighed
quantity in rather than filling to a pressure.

Tim

I could weigh the whole freezer, but would then have to either track the
weight of the contents too, and also take into consideration the weight
of any frost build-up too :-)

Well, I did say "obvious", not "easy". ;-)

I can see the pressure readings while off will be of no use, as the
pressure will be the same no matter how much refrigerant is in there
(assuming there is some in liquid state), but when running, the high and
low sides should behave in a particular way depending on the type of
refrigerant and how much there is in there - I think it has something to
do with a pressure temperature chart like this
http://refspecs.co.nz/cms/uploads/fi...PT%20Chart.pdf

But I am not sure...

As the freezer appears to be working fine with the suction side at 0 when
running, maybe that is the answer...

Your seem to be well on your way to becoming a refrigeration expert anyway
so I suspect you know more about the subject than 99% of the folk here (me
included). ;-)

Tim

:-) been doing my homework! I was hoping there may be a proper
refrigeration expert lurking to fill in the gaps :-)

Also interested in a cheap leak detector for R600a and if it works on R410a
then that would be great too...

--
Toby... remove pants to reply

In days of yore when freon gas was used, there were special blowlamps
for detecting leaks that had a rubber pipe attached. The end of the
pipe was used to detect leaks, the flame changed to a green colour.
But that wouldn't work on butane.

"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.

On Sunday, April 7, 2013 6:11:34 PM UTC+1, Toby wrote:

Hello!
I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.
So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)
My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?
Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)
Thanks for any pointers :-)

I guess you could put a how-to on the wiki if you like


NT

On 08/04/2013 11:57, wrote:
On Sunday, April 7, 2013 6:11:34 PM UTC+1, Toby wrote:

Hello!
I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.
So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)
My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?
Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)
Thanks for any pointers :-)

I guess you could put a how-to on the wiki if you like


NT


Good idea - Done!
http://wiki.diyfaq.org.uk/index.php?..._%28R600a%2 9



--
Toby...
Remove pants to reply

On Monday, April 8, 2013 10:24:21 PM UTC+1, Toby wrote:
On 08/04/2013 11:57, wrote:

I guess you could put a how-to on the wiki if you like

Good idea - Done!

http://wiki.diyfaq.org.uk/index.php?..._%28R600a%2 9

nice one


NT

On 08/04/2013 23:02, wrote:
On Monday, April 8, 2013 10:24:21 PM UTC+1, Toby wrote:
On 08/04/2013 11:57, wrote:

I guess you could put a how-to on the wiki if you like

Good idea - Done!

http://wiki.diyfaq.org.uk/index.php?..._%28R600a%2 9

nice one


NT

Can I link to a file but use a custom word, rather than it showing as
Media:FILENAME.PNG ?




--
Toby...
Remove pants to reply

Toby wrote:
On 08/04/2013 11:57, wrote:
On Sunday, April 7, 2013 6:11:34 PM UTC+1, Toby wrote:

Hello!
I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.
So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)
My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?
Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)
Thanks for any pointers :-)

I guess you could put a how-to on the wiki if you like


NT


Good idea - Done!
http://wiki.diyfaq.org.uk/index.php?..._%28R600a%2 9




hydrocarbons are a bit more forgiving of moisture than other
refrigerants (although better to not have any)
I connect both red and blue hoses and leave them connected through the
whole operation and just do every thing else through the yellow hose.
ie vent gas, connect to vac pump,connect to charge cylinder etc.
I usually put a bit of uhf dye in yellow hose just before connecting
charge cyl (saves having to buy expensive equipment to inject dye under
pressure). This allowes you to look for leaks with uv light later.

On Mon, 08 Apr 2013 23:08:37 +0100, Toby wrote:

Can I link to a file but use a custom word, rather than it showing as
Media:FILENAME.PNG ?

http://www.mediawiki.org/wiki/Help:Images

--
Cheers
Dave.

On Monday, April 8, 2013 11:08:37 PM UTC+1, Toby wrote:
On 08/04/2013 23:02, wrote:

On Monday, April 8, 2013 10:24:21 PM UTC+1, Toby wrote:

On 08/04/2013 11:57, wrote:



I guess you could put a how-to on the wiki if you like



Good idea - Done!



http://wiki.diyfaq.org.uk/index.php?..._%28R600a%2 9



nice one





NT



Can I link to a file but use a custom word, rather than it showing as

Media:FILENAME.PNG ?

Yes, but its unclear what you mean. Please explain

If you mean words that show up when you mouse them, see
http://wiki.diyfaq.org.uk/index.php?title=Spanner
for picture coding

If you mean linking to a pic file, you can create a webpage with just that pic on it and call it whatever you want.

Also what the webpage shows and what it links to can be different, eg
[[con job|get rich]]

PS its recommended to only capitalise the first word of page titles, otherwise searches cause problems and linking is slower.


NT

On 07/04/2013 18:11, Toby wrote:
Hello!

I have been given a freezer (Hotpoint FZ150) that wasn't working
properly, (after being turned on for a while, it would lock out and
alarm because it was not getting cold enough) - it had the signs of low
refrigerant, so I bought a set of gauges, and that confirmed it was
indeed extremely low, pulling down to about 18inHg on the suction side
when running.

So, I bought some R600a refrigerant and then used an old freezer
compressor to vacuum the system out (after venting what little R600a
there was outside (As it is just butane, this is OK, apparently) The old
compressor got it down to just over 20inHg, which I was happy with for a
DIY job :-)

My question is, how do I know if there is enough refrigerant in the
system if I check it at a later date without having to wait for it to be
so low it stops cooling and alarms? I weighed in the amount it stated I
needed on the data plate, but if it does need topping up at a later date
(which I assume is likely if there is a small leak somewhere (which I
will try to find)) then how do I tell how much is in there at any given
time?

Is it to do with the pressure on the suction side when the compressor is
running? (It is working fine now by the way)

Thanks for any pointers :-)


Just as an update to this, the freezer ran put of gas again after about
a week, and after much searching, I found a leak on the pipe joint
between the capillary tube, and the evaporator (inside the freezer)

The evaporator is aluminium, so when I tired to braze the connection, I
melted the aluminium pipe a bit :-( (Original was crimped, with some
glue type stuff too.)

I have now jointed it with J-B Weld, as the pressures are not very high
with R600a, so once that has fully set, I will see if it still leaks!


--
Toby...
Remove pants to reply