Secondary System

[rac]

Looking at installing a secondary system on medium temperature supermarket refrigeration system, going to pump glycol instead of refrigerant, what's your thoughts, cost is more for the equipment and install as well as operating cost, is it really worth it? Will reduce refrigerant charge by half, still going conventional DX on low temp.

[juneair]

how much of an increase in operating costs?
The charge should be alot lower then half. The system we did would have been easily a 1500lb charge and it only used 300lbs. The savings in refrigerant cost ( r404) was almost 10K.

These sytems are alot easier to leak check to say the least and the case controls were idiot proof.

[thegoodhumorman]

secondary works pretty darn good-
-its a bit different in needing to size pumps and whatnot
but have seen most work well-
even individual cases out here on secondary (svc mt)

believe that this could be the future of market refrig.-
which wouldnt be too bad in that locating leaks with the
new refrigerants can be a "pita".

course they said that about two stage r22....score one for the Montreal protocol...

[kooltek]

Secondary system is all Wegman's uses on med. temp. Works great. Very tight temps and approaches (coil temp to disch air temp). Warm glycol is used for the defrost with only small amount of temp rise and shelf temp. Service meat cases (Hill) use cold plates chilled directly by the glycol and the product rests right on it! Secondary systems are very big in Europe due to refrigerant penalties. These systems cut refrigerant use substantially. If used with evap condensers and plate heat exchangers for heat recovery charge is only a few hundred lbs. One store uses air cooled condensers with receivers mounted on roof and it is usually out of the system, only there for holding split condenser charge. VFD controlled also. Cool stuff.