Re: holdover refrigeration
R404a, why would you replace R12 with that.
Compare it on PT chart to see what I mean, totally different.
Re: holdover refrigeration
ok, i looked at PT chart in regards to R404a, i do understand that you must mean its higher pressure at the same temp (-10) when compared to R12 (almost 20 psi)
R134a will have less pressure at the same temp as R12.
I understand that some compressors will run into a vacuum when they get close to design temp for low temp applications. I get the basic temp and pressure relationship but not how its able to work fully.
So should i take my thinking back to replacing that R12 unit and replace with R134a?
what else should i look into for my situation?
Re: holdover refrigeration
I would source a drop in for r12,134a retrofit will need all the oil removing and replacing with lubricant that suits.
Re: holdover refrigeration
ok...so MP66??? i can not buy an R12 unit...MP66 works with POE oil...can i get an r134a condesing unit and charge with mp66? if not why?
Im understand i can use R401B, R409A, R414B, R417C, are replacements for R12 low temp application.
the thing is i have little experience with temp glide...
Re: holdover refrigeration
Short answer is yes if you are changing the unit,the problem will be if there is any old mineral oil in the evaporator etc, remember most drop ins are charged liquid not vapour 134a is vapour charge so be very very carefully how you charge with liquid you could damage the compressor.
Re: holdover refrigeration
Thanks again for your reply.
another question is can i just use my nitrogen to blow out the old oil? should i use RX11 for just the evap section and then flush with nitrogen? will that help at all to remove the old mineral oil?
Re: holdover refrigeration
Yes but you will need good evacuation,via a vacuum pump to remove any moisture etc,be carefully to make sure the oxygen free nitrogen has been vented,then fit a new filter drier .
Re: holdover refrigeration
sounds good. thanks for your help
Re: holdover refrigeration
No problem,keep us updated on your progress,happy safe sailing take care.
Re: holdover refrigeration
you got it bud.
its not a sail boat, its a motor yacht.
But i hear you "wear my life jacket"
Head on over to Long Beach CA, would love to buy you a beer ;)