CAPACITY

[NANOTECH]

Does changing an existing KT53 powerhead (R22) to a KT53 powerhead (R404A) change the valves capacity at all?

[icemeister]

Changing the thermostatic element has no effect an the valve capacity but the change in refrigerant type does.

A good example would be to look at a Sporlan Q valve with a #2 cartridge and compare the nominal capacity with R22 vs R404A. Using R22, a valve with that cartridge has a capacity of 1 ton, but with R404A it's only 1/2 ton.

http://www.sporlanonline.com/10-10_072008.pdf (See p.18)

[NANOTECH]

With these valves not being Qs, how will I determine how much capacity I have lost if any? (Changing from R22 to R404A)

[icemeister]

The change in capacity will be proportionally the same with any type of valve.

[NANOTECH]

So I have decreased the capacity of the valves by half!!?

[icemeister]

So I have decreased the capacity of the valves by half!!?

Yes.

[NANOTECH]

Does this mean for example if we have a 12' produce case that requires 12000 BTU's @ 25 deg. SST to maintain 35 deg. discharge air using R22 Now using R404A we only have the ability to remove 6000 BTU's ??

[icemeister]

Does this mean for example if we have a 12' produce case that requires 12000 BTU's @ 25 deg. SST to maintain 35 deg. discharge air using R22 Now using R404A we only have the ability to remove 6000 BTU's ??

Generally speaking yes, that's true. But in reality I think most valves are somewhat oversized to begin with. Add to that a built-in reserve capacity of 20-30%, then derate it for R404A and you'll probably still be close enough to "get by".

[icemeister]

If you look into the expanded ratings, the relationship between R22/R404A capacity (at +20ºF at least) is more like 66% than 50%.