Can you mix R-410a and R-22 equipment?

“Can you install an R-410a condensing unit matched with an R-22 evaporator coil?”

We get asked this question often, so we thought it would be helpful to write a post about it. 

So, if you replace an R-22 condensing unit with an R-410a machine, do you have to replace the evaporator coil?

Now for everyone’s FAVORITE answer…maybe.

First let’s talk about the major concern everyone has: pressure.

We all know that R-410a runs at a higher pressure than R-22, so yes, this should be a concern. 

An R-22 evaporator coil operating in A/C mode, will run at approximately 70 PSI. An R-410a coil, conversely, at the same conditions will run at 130 PSI. Almost double the pressure. 

At first glance this looks concerning. But remember, R-22 coils are typically tested to 300-400 PSI, which is a much higher pressure than R-410a will ever run on the low side. 

Now that we have that concern out of the way, here are your rules of thumb:

When to NOT match an R-22 coil with an R-410a condensing unit:

  1. You should never use an R-22 evaporator coil with an R-410a outdoor unit if the outdoor unit is a HEAT PUMP.
  2. You should never reuse an R-22 evaporator coil if tin and antimony were used in the brazing process. By the way, if you find a coil like this it will be ancient. Manufacturers stopped using this process in the early 1950’s. 

If you have made it this far and decide that you will reuse the existing R-22 coil, your next step is to consult the attached document from York.

You will need to flush the system, removing all residual mineral oil, replace the TXV’s, remove pump down control, along with a few other steps and careful considerations. 

Note: cooling capacity and efficiency cannot be guaranteed. But what we can tell you from experience, is we have never had a customer complain about lack of cooling capacity after the change out. 

If you have any questions or would like us to look at a job with you, please call us at (800) 322-9675!
JCI-EquipmentMix410A-R22-approved.doc (19 downloads)

Brad Telker
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Brad Telker

Brad has been in the HVAC industry and at cfm Distributors since 2006, and is actively involved in HARDI as well as the local Kansas City chapter of ASHRAE. Brad has been a semi-professional blogger since late 2015 and is a huge fan of Apple's new 3D Touch technology.
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