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slackbladder
25-08-2013, 12:29 PM
Hi all been doing Air con for a few years but company i was with went down the pan.. 8(

have started with a new firm and have got to re commision a r404a cold room

just wanted to ask a few pointers as never even used 404a..

the room needs to be -18c and im hoping a sight glass is fitted..

after a good vac etc should i be able to just charge to a full sight glass to get room to -18c or is it gonna be a case of taking temps onto evap and compare to suction pressure/temp??

any help will be great help!!!

Brian_UK
25-08-2013, 01:38 PM
A sight glass will be useful but don't expect it to indicate what you want until the room is down to temperature.

Be aware that the compressor may be overloaded on pull down, depending on equipment fitted of course, so be prepared to throttle it back until the load eases.

chemi-cool
25-08-2013, 02:29 PM
and remember that R-404 should be filled only as liquid!!

slackbladder
25-08-2013, 04:10 PM
thnx guys...

so at start off room will be 20c ish what sort of suction/high side would you think to see?

and at -18c 1bar ish??

thnx

chemi-cool
25-08-2013, 05:29 PM
At -18 it should be 25 psi, thats -23 evaporating temp.
Check and correct the superheat at about -15,[only if you need to]

slackbladder
25-08-2013, 10:23 PM
At -18 it should be 25 psi, thats -23 evaporating temp.
Check and correct the superheat at about -15,[only if you need to]

Nice one..

after a change of drier and a good vac ill bomb charge with liquid and hopefully see that temp drop!!!

wheresmyspanner
24-10-2013, 01:25 PM
My advice would be to get an in date comparator, they even do an app for that these days