First, let me introduce myself so you all have a better idea of where I'm coming from.

My name's Marcus. I'm a student at a university on Boston and am majoring in mechanical engineering, although that's looking like an increasingly poor choice as the math courses pile up. My interests are largely in transportation, so refrigeration and HVAC aren't topics with which I'm particularly well-versed.

That said, what I'm trying to figure out is how to replace R-22 in a heat pump system without losing a tremendous amount of capacity. Most of the literature I've seen comes from refrigerant manufacturers, all of whom claim that their refrigerant (R-422b, R-422d, R-407c, etc.) is the best replacement choice given the upcoming R-22 phaseout.

I need to know this because I'd like to be able to reduce the total number of changes to a heat pump designed for R-22. I'm not sure how easy it is to add capacity to a system, but it's bound to be easier if the new refrigerant is as similar to R-22 as possible.

Any ideas?

Thanks.