R438a and R422D

[mikeref]

Current replacements for R22 in Queensland is R438a and R422d.
Has anyone had issues with these Blends?

My bad as i haven't logged in to R.E. for several months :o

[al]

I've used 422d with no issues, not come across the other one. Only issue is that the replacement is more prone to leaking.

[monkey spanners]

R422D is crap in milk tanks imo, runs about 1bar lower suction than it did on R22 with consequent drop in capacity.
Have used R438A on an ice builder and also as drop in for big air con system, both seem to work ok.

Nothing will be as good as R22

[RANGER1]

Mike you may already have, but for general information.

http://www.heatcraft.com.au/component/docman/doc_view/267-gas2go-r22-service-and-retrofit-alternatives-may17

[Grizzly]

Mike you may already have, but for general information.

http://www.heatcraft.com.au/component/docman/doc_view/267-gas2go-r22-service-and-retrofit-alternatives-may17

Hi Ranger.

It's me being thick and misunderstanding the terminology.

But can you explain the following.
Which is listed as 1 of the benefits of 407c.

" Can be topped off charge
during service."

[chemi-cool]

Hi Mike,
I am using 438 for several years now from cold stores through milk tanks and down to CO2 tanks at -30 C evaporating temp.
No complains, its the job very good,
As MS notes, its a blend and should be charged as liquid, you can expect cooling problems if you loose more than 20% of the charge.
No changes to the system, it runs OK with mineral and poe oils.
Only TXV need a small adjustment.
Run a good leak test before you charge it in.

[Glenn Moore]

Hi Mike
Have loads of experience with R422D refrigerant. This refrigerant can cause loss of capacity up to 20% and seen this happen many times , but you can get some of the capacity back by fitting the next size up orifice into the expansion valve, as the old R22 tev are not particularly compatible with R422D, and tweaking the tev to a reasonably low superheat setting close to its operating condition.
The other problem with R422D is problems with oil return or lack of it when using the original mineral oil type . I was involved in retrofitting R422D into 2 identical York chillers on a site in London
One system worked perfectly well with the original mineral oil in the system . The other chiller had a serious lack of oil return and we had to then remove the mineral oil from the system and replenish with POE this worked perfectly . Most of the larger fridge companies in the UK now automatically replace the mineral oil with POE during the retrofit to prevent the need to remove the mineral oil later if oil return problems occur. This just doubles the work and costs.
R438A refrigerant seems to work ok but the systems I’ve worked on had electronic expansion valves fitted with R438A refrigerant in the controllers software so the valve is perfectly matched with the refrigerant curve.
The big problem when retrofitting to a new refrigerant is when the expansion device is designed for a different refrigerant ,this makes the thermostatic expansion valve a poor liquid injection device.
The reason for this is when the charge for an expansion valve power assembly is designed the charge element is derived to give a constant static superheat across the Tevs evaporating temperature band. So if the range of the Tev is like an N range Danfoss ie plus 10 C to minus 40C the static superheat will be 5k when it’s evaporating at plus 10C and at 5k when it’s evaporating down at minus 40C . But when the tev fitted is a different type than the refrigerant in the system ie R22 valve with R422D refrigerant the static superheat curve is no longer the same due to the pressure temperature curve of the new refrigerant . As everyone says you need to tweak the tev a bit, but to get full efficiency from the mismatch tev and refrigerant you would need to constantly adjust the tev to keep the optimum superheat across the Tevs working range. In theory you can use an R22 or R407C or R404A valves with these “new refrigerants “ but the superheat will change sometimes dramatically .Mostly you have to shut the valve in to prevent liquid flood back at a high Evaporating conditions ,but as the evaporating temperature reduces the static superheat often gets much larger causing high suction superheat and lower system capacity.
To keep any retrofitted system energy optimised it will need to have an electronic expansion valve fitted with the refrigerant curve for the refrigerant in the system in the controller then the static superheat will again be constant across the evaporating range of the system.
No manufacturer will produce a thermostatic expansion valve designed specifically for the hundreds of gases coming onto the market every day as it’s not viable as the market hasn’t got a clue what new rules governments will come up with and so systems which once worked perfectly well are now running in an unstable condition as the main control for the refrigerant flow is no longer the true brains of the outfit as the tev is now trying to control an alien fluid which is incompatible with what it was designed for .
I had to fit electronic expansion valves to a large system that one of the gas suppliers where using to convince a large customer to retro fit all their systems too. With the original tev tweaked for the new refrigerant they could not achieve the duties they were claiming for the refrigerant , but as I tried to explain to them the valve power assembly charge was never designed to work with any other refrigerant than the refrigerant as marked on the valve.
With EEV,s you can easily see the superheat control although many EEV,s are left at factory settings due to poor knowledge of how to set the various parameters to get the ultimate superheat control from the valve.
Likewise TEV,s are often left at factory setting again due to lack of knowledge or the old chestnut “ it comes factory set” so already the TEV is performing poorly and this is compounded that it’s trying to control an alien refrigerant ,but nobody really knows unless they monitor their energy consumption like a hawk.

[RANGER1]

Hi Ranger.

It's me being thick and misunderstanding the terminology.

But can you explain the following.
Which is listed as 1 of the benefits of 407c.

" Can be topped off charge
during service."

Grizzly, I admit to knowing next to nothing about these refrigerants.
In this paper it also mentions you can top up R407c a number of times without problems,
but whether this is true?

The link below does not work, but a few papers indicate top up if not critically charged system.

https://www.chemours.com/Refrigerants/en_US/assets/downloads/*****-407c-frequently-asked-questions.pdf

[Grizzly]

Grizzly, I admit to knowing next to nothing about these refrigerants.
In this paper it also mentions you can top up R407c a number of times without problems,
but whether this is true?

The link below does not work, but a few papers indicate top up if not critically charged system.

https://www.chemours.com/Refrigerants/en_US/assets/downloads/*****-407c-frequently-asked-questions.pdf

Thanks for the reply my friend!
I thought that was what the wording was implying.
However over here in the U.K / E.U if you apply 2079. regs.
You cannot just top up a system any more and given the cost of these refrigerants.
Its important to identify and rectify the cause of the leak.
In Fairness the size of the 404a systems I tend to work on. Means that you really don't have a clue what the

[al]

Brilliant post Glenn!

[mikeref]

Thankyou for your comments guys.

[mikeref]

Thankyou . I was figuring a temperature glide would make a my Saturated Suction Temperature rise over an 18 ish metre run.

[RANGER1]

Thankyou . I was figuring a temperature glide would make a my Saturated Suction Temperature rise over an 18 ish metre run.

I would have thought that glide would only be case with superheat at evaporator outlet, not suction line.
most compressors limit it to 20 degC superheat at compressor suction stop valve.

[mikeref]

I would have thought that glide would only be case with superheat at evaporator outlet, not suction line.
most compressors limit it to 20 degC superheat at compressor suction stop valve.

You are correct Ranger1. Incorrect wording on my comment. Temperature glide at evaporator outlet will have a significant effect on Suction line temperature over an 18 Metre run.... http://www.refrigeration-engineer.com/forums/member.php?74885-Glenn-Moore has the answer. Cheers.