R22 to R422D Retrofit

[dantheguru]

Hi all

Has anyone done a retro on a water chiller from R22 to R422D?
We have just started one and are having problems with low back pressure and high superheat. The EEV software cannot cope with the new refrigerant and when we manually overide it goes back to default.

Any ideas?

[El Padre]

Hi Dan,

I have been asked to quote for a similar job, I know that the main performance difference is a high reduction in discharge superheat, if its a screw compressor this could affect its control/performance significantly, if you post the chiller details you may well get a response from someone that works for the manufacturer.

Cheers

[james10]

i carried out the same task to a carrier 30HW with 06B recips the major problem we had was with the oil as the make up of R422d is 75% R134a which needs ester oil although we were told that the new refrigerant would be ok with the current mineral oil we were using (3GS) when we changed the oil to ester (emkrate 68) the oil problems dissapered as for the low back pressure i would check the transducers (if used) are reading correctly also the outputs off the EEV driver also have you checked that the valve is motoring correctly hope this helps like El Padre said the chiller details would help

[Refrigerologist]

Hi all

Has anyone done a retro on a water chiller from R22 to R422D?
We have just started one and are having problems with low back pressure and high superheat. The EEV software cannot cope with the new refrigerant and when we manually overide it goes back to default.

Any ideas?

Hi

I have converted 2 Trane chillers and 1 Carrier to R422D with no problems at all. I did change the oil on one system, but this was to to Suniso 3GS which is mineral oil! This should not be necessary and I only did it because the compressor oil level was very low!

Have you changed the expansion valve orifice? You may find you need the next size up in order to maintain the correct superheat and raise the suction pressure.

Isceon do have a a recommended guide to the conversion and also have a pressure/temperature relationship chart so that you can check the superheat and subcooling values.

BTW: The chillers have been operating successfully since April 2006 with no problems at all!

[neil74]

We have had a similar problem on a couple of York chillers although they had thermostatic valves but we just can't get the duty at 100%, the suction pressure was around 3 bar and something like 16' s/h. Can't seem to find any good info even fromthe likes of Danfoss although l have seen you need to increase the duty of the exspansion device by 30% not sure if it's true though.

[dantheguru]

thanks for all your replies

We have had Danfoss in and they have changed the software for the EEV. The circuits are much more stable now although still not perfect.

We are running on plain CHW so the glide is causing us an issue at 6 deg? any ideas apart form the obvious addition of glycol to combat this?
Oil return is better, but we still need more POE it would seem.

This refirgerant is no straight forward drop in form the experience we have had!

cheers

[PORKYPIG]

Just converted ours today.... The ref. guys are tell me that the suction pressure is now at 2 bars as compared to 3,5 with R22... I noticed that the units have lost capacity....

What I find strange is that I can see the referigerant bubbling through the sight glass.... the ref. tech. tell me that this is ok... I´m not a Ref. engineer, but I know that with R22 this mean´t a shortage of gas..

Am I being conned ??

[taz24]

Just converted ours today.... The ref. guys are tell me that the suction pressure is now at 2 bars as compared to 3,5 with R22... I noticed that the units have lost capacity....

What I find strange is that I can see the referigerant bubbling through the sight glass.... the ref. tech. tell me that this is ok... I´m not a Ref. engineer, but I know that with R22 this mean´t a shortage of gas..

Am I being conned ??

No you are not being conned.

With the different refigerant the system does operate
a little differently. Yes bubbles in the sight glass did
mean it was short of refrigerant but unfortunatly it
is not the best indicator for correct charge with the new refrigerant.

Not very satisfactory I know but it is a problem with retrofitting old systems with new refigerants.

taz.

.

[Peter_1]

I have to make a quote for 2 packs: do you change all the rubber seals in the SV's?

[taz24]

I have to make a quote for 2 packs: do you change all the rubber seals in the SV's?

Yes Peter.

All seals on valves and solenoids need replacing even TEV's if
possible and cost effective, if you don't the seals will last a
few days to a few weeks then go.

i have seen many, many site in the Uk that have been retrofitted
to 422d and it combined with the new oil just eats the seals.

I have seen ball valves on liquid headers that were impossible to
opperate because when the cap was removed to access the valve
it peeed liquid out at high pressure.

So do the seals with the replacement of the refrigerant and save
yourself and the customer a whole lot of grief.

Cheers taz

.

[Peter_1]

I asked this because if you read the technical documentation of Dupont, you just have to switch the refrigerant and that's it. I couldn't believe this.

[taz24]

I asked this because if you read the technical documentation of Dupont, you just have to switch the refrigerant and that's it. I couldn't believe this.

In the UK Honeywell have 3 or 4 lorry trailers that are
set up for the retrofit. They blitz the store and prep
the store ready then on a Friday they go in mob handed
and they remove all the refrigerant, replace all the headers,
TEV's and all valves. The system is then pressure tested and
vacced out ready for refrigerant charging. All done and dusted
and the store is trading by Monday morning.

They found in the early refits that if the valves were
not replaced they failed and a lot of refrigerant was lost.

Cheers taz

.

[robref]

Hi, I am going to retrofit an R22 Carrier Chiller 30DQ-120 with recip compressor. I am quite mixed up if will use the R417A or R422D. Also seen that no one is confirming anything about oil change and oil seals. Also heared that the refrigerant charge should not be charged the same weight as stipultaed per chiller nameplate but a 10% lower.

Please advise

[yorkie10]

R422d (isceon 29) is primarily designed for water chillers where as R417a (isceon 59) is for air conditoning application, there are two other common ones Isceon 79 for low temperature and Isceon 99 which is set to replace I29 to give a lower glide and better oil return in chilled water systems. I have done several I29 conversions from R22 with great success but each one has been treated as a bespoke job, I now as a matter of course drain and recharge the compressor oil with POE. If you look at the make up of I29 (R422D) there is 3% iso-butane added which is miscible with mineral oil, on many occassions this is not sufficient and evap logging occurred, POE overcame the issue, on all occassions there is at least 8% duty loss compared with R22, has been upto 15%.

[choochoo!]

you should convert from r22 to r404a the ucm-cld controller may have r404a programmed on it, if not you'll have to replace eev and modules, the main concern with using drop in gases is the oil return due to the oil separators being externally mounted. carried out retrofit recently to r404a on a system where the previous contractor had tried mo59
found large amount of oil sat in evap!

[Fri3Oil System]

Hi, we have several case studies about retrofits.
Specially we have an interesting one on a Chiller, where we compared its 2 circuits, one retrofitted to 422d and the other to 407, with our recomended cleaning procedure.
I will be happy to send you this file if interested.
regards
Check this link for retrofits info:
www.fri3oilsystem.com/june.zip

[VeryFastFish@BE]

Please see our article referring to the conversion.

This can be found at businessedgeltd website in the masterclass section.