I need freezer guru!!!

[allstar08]

I have been working on a walk in freezer. Old school Hussman 1hp semi herm, 502. It had not been serviced in years, any multiple leaks etc. I charged the unit to a reasonable super heat of 15 at the compressor, and the sub cool was around 15 also. I added oil to get the pressure around 50. I went back today to do a follow up and the suction side of the compressor had about an inch of ice on it. The only way I was able to get a low side reading was from a schrader port I installed. Today I had a 13# sp with a -8 line temp and a 73 degree liquid line at 185. The numbers are good, but why all the ice? I obviously don't have freezer experience.

[markettech]

I'm confused here:confused:

A 1 hp walk-in freezer system should have a liquid line sight glass...why not charge to a full sight glass?

A 1 hp compressor does not have an oil pump - how were you reading 50 psig net oil?

A few other things:

We typically don't do subcool......most times superheat is sufficient.

+20F to +40F superheat at the compressor is the 'sweet spot'

+4F to +6F superheat at the outlet of the evaporator is nice.

A suction line below +32F will collect ice....it is not abnormal...it is a law of the Universe (something about water changing state from a liquid to a solid at +32F)

[Phase Loss]

yup a -8* line will cause the natural phenomenon of ice creation.

also, why isn't your suction line insulated?

[jpsmith1cm]

Yup, for some reason, water freezes at 32 degrees. Can't figure it out for the life of me.

I've just learned to deal. :D

Markettech is right, small pumps don't have positive pressure oil pumps, so this is bigger than 1hp or you weren't measuring oil pressure.

If you did take an oil pressure, did you do it correctly? Output - sump = net.

If you were low on refrigerant and added oil too quickly, you may now be overcharged on oil as low charge will lead to low oil return.

[pecmsg]

I have been working on a walk in freezer. Old school Hussman 1hp semi herm, 502. It had not been serviced in years, any multiple leaks etc.

What refrigerant did you use?
and Fix The Leaks

[A1 Burt]

It sound's like this system need's some care
Find leek-recover refregient-Change filter-Add sight glass-Change oil-Check
T-X-V For S-H - bulb contack- clein screen-air flow across coil-make sure defrost is working right -check that fan's are not turning on too quick-
just a few thing's too think about:cool:

[rayr]

Two words come to mind DEW POINT

[crackertech]

Two words come to mind DEW POINT

That says it all right their.Just because the pump or lines have ice or frost on
is not a true indicator of flood back.

[markettech]

Just because the pump or lines have ice or frost on is not a true indicator of flood back.

I just don't understand CT........care to expand on this a little bit?















:D

[jpsmith1cm]

You mean all the suction lines on my low temp rack aren't supposed to be dry and ice-free??

:D

[crackertech]

You mean all the suction lines on my low temp rack aren't supposed to be dry and ice-free??

:D

I work with guy's that think that they should be.:o:eek::eek:
You know R-22 low temp I/C walkin FRZ -12 3 deg super heat at coil.Naaa.....
not a chance of ice or frost on them lines.:rolleyes:;)

[jpsmith1cm]

I got in trouble for not chasing "floodback" on a -23 rack. Suction temp at the rack was 0 to -2.

That was supposedly floodback.

[crackertech]

I like to take the cap off of the suction valve core at the sorit depress with pocket screw driver and ask wheres the liquid.

[jpsmith1cm]

I wasn't there. Phone call 2 days later.

I had made a notation in the logbook that system such-and-such was NOT flooding, counter to what he had written and that he did not need to spend the time chasing TXVs.

Boss-man read it, called me screaming, called the other guy and he got the TXV adjusted.

Dumba$$.

[allstar08]

Just getting back you east coast guys are 3 ahead. You are right it must be larger then 1hp it has an oil pump and I did get net oil press at the right spots. I am almost as dumb as I look, but not quite. It does have a sight glass and that is only a reference point in which to get close in my opinion. When I started this thing had no sub cool and like 40 deg of super heat, and the glass showed no bubbles after the receiver.

[allstar08]

The lines are insulated the ice is forming on the suction end bell.

[crackertech]

The lines are insulated the ice is forming on the suction end bell.

And your point is? Have you read this thread? the ice is forming on the suction end bell And so what does that mean?

[markettech]

And your point is? Have you read this thread? the ice is forming on the suction end bell And so what does that mean?

Whoa..........down boy.

I think you need to get your hands on a rack - that oughta calm you down;)........:D

[rkious]

If you have a -10 freezer a -20 sst would be normal . IF you have 30
degree's of superheat at the compressor that would give you 10 degree
suction line . If you have a 10 to 20 degree suction line at the compressor,
whats going to happen? Clearing the sight glass and checking your Evaporator and compressor superheat means a lot in refrigeration. ( on another note .... keeping the system dry means a lot too. ) Don't worry
about ice on the suction line and end bell on a freezer compressor.... as long
as you have taken care of the superheat .


Ross Kious

[allstar08]

And your point is? Have you read this thread? the ice is forming on the suction end bell And so what does that mean?

Please cut me some slack. I have not seen a lot of freezers, I work mostly on the air side. I took this call and I had some questions, it just seemed like a lot of ice, and I was curious about flood back, or maybe a txv issue. Thanks everyone for all your help.

[Phase Loss]

first dew point followed by frost point:)

[markettech]

first dew point followed by frost point:)

Not sure why, but suddenly I'm thirsty for a beer:D

[rocket]

"I just don't understand CT........care to expand on this a little bit?"
if suction line is very cold and moisture is in the room, you will have icing
moisture will condense on coldest spot, if that spot is below freezing - ICE!

if your suction pressure is where is hould be and your lines are insulated, you can keep your beer colld on that ice.

example: bakery freezers usually completely encased in ice.

[crackertech]

"I just don't understand CT........care to expand on this a little bit?"
if suction line is very cold and moisture is in the room, you will have icing
moisture will condense on coldest spot, if that spot is below freezing - ICE!

if your suction pressure is where is hould be and your lines are insulated, you can keep your beer colld on that ice.

example: bakery freezers usually completely encased in ice.

I'm pretty sure MT got it.:cool:

[refexp]

I would confirm a 4 to 8 F superheat at the evap and let the compressor superheat settle. Thats why on a rack you rarely see ice especially with a 100ft + run. Ice at compressor could sometimes mean ice coil.

[crackertech]

I would confirm a 4 to 8 F superheat at the evap and let the compressor superheat settle. Thats why on a rack you rarely see ice especially with a 100ft + run. Ice at compressor could sometimes mean ice coil.

Or lot's of other thing's.:cool: