The HCFC phase out is leading to the introduction of a number of new retrofit gases which present a new technical challenge to the marketplace as they are not the same as R22. The following information can assist in deciding on whether to carry out a retrofit and if so what is the best option to go for.
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Retrofit gases
There are over 10 different retrofit gases that have come on to the market as replacements for R22, all of them are application specific and can’t function over the temperature range that R22 covered. These gases have the advantage of being designed to run at similar pressures to R22 and work with traditional lubricants providing the option of a simpler retrofit. They are a very viable option for keeping existing systems running after the phase out so long as one is aware of their differences to R22 and potential problem areas
The differences between these gases and R22 are as follows:
- The gases have a lower latent heat than R22 – therefore every kg of liquid that goes into the evaporator moves less heat
- At the same degree of subcooling as R22 these gases have a higher percentage of flash gas when they go through the expansion valve – therefore less usable liquid reaches the evaporator than with R22
- Most of these gases have a higher vapour density than R22 – therefore the compressor can move a higher mass of gas around the system with each stroke than R22
Points 1 and 2 lead to a significant drop in capacity, this is however compensated for by point 3. With these gases it is necessary to open the expansion valve to increase mass flow around the system, the extra mass flow will help make up for the lower latent heats and higher flash gas.
Although increasing the mass flow will compensate for capacity loss, it is unlikely you will achieve the same as R22 and there is generally a slight loss when doing the retrofit along with a slight loss of COP meaning a rise in running costs for the kit. This means that not every system is suitable to be retrofitted with these gases, if the system is in anyway short on capacity the problem will only get worse with these gases and retrofit is not recommended.
Full Retrofit to Mainstream HFC
Doing a full retrofit to a mainstream HFC such as R404A, R507 or R407C can be beneficial from a cost perspective and shouldn’t be discounted. These gases are however not designed to mirror R22 pressures and don’t work with traditional lubricants making the retrofit potentially more complicated.
These gases can really be a benefit with systems that are short on capacity and unsuitable for retrofit to the Isceon or RS retrofit replacements. R407C operates at similar pressures to R22 and exhibits a capacity loss slightly less than that of the Isceon or RS products, while R404A and R507 can provide the same capacity or a capacity increase depending on the operating temperature but work at a higher pressure.
Why not call A-Gas on 01275 376 600 to discuss in more detail?