[Bldg-sim] R-410a & EA credit 4 (UNCLASSIFIED)

[Dahlstrom, Aaron]

Agree with all the previous comments; I'll also point out that split systems can be tough if there are long line-sets.

Aaron Dahlstrom , PE, LEED(r) AP
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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jeremy Poling
Sent: Monday, January 31, 2011 2:34 PM
To: Cheney; Eurek, John S NWO
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] R-410a & EA credit 4 (UNCLASSIFIED)

My experience has been the same as James - the smaller units typically have more of a problem, particularly RTUs less than 10 tons.  The refrigerant charge is high compared to the maximum allowable to get a total Refrigerant Impact per Ton <100.

Also, I just ran into this on a project as well - there are "supercharged" chillers on the market that also have high charge-per-ton numbers.

See Page 210 of the LEED-BDC reference guide for a table showing the maximum refrigerant charges for typical refrigerants.  For RTUs, 15-year life, you have to be less than 1.98 lbs/ton and the last I remember only Trane had a unit at that low of a charge and still met ASHRAE 90.1 minimum efficiencies.

Jeremy R. Poling, PE, LEED AP+BDC


From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Cheney
Sent: Monday, January 31, 2011 12:40 PM
To: Eurek, John S NWO
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] R-410a & EA credit 4 (UNCLASSIFIED)

Hi Eurek,

The answer to your question is VERY LIKELY.

Why?

* Since R-410a will have 0 ODP and relatively small GWP (1890). Eventually the equation is decided by only LCGWP, since LCODPx10^5 will be 0.
* My personal feeling is that Rc (Refrigerant charge) is critical in your case. The range is from 0.5 to 5 lbs of refrigerant per ton. The smaller the better.
* Considering multi types of equipments, as long as your averaged LCGWP is less than 100, you will be safe.

As suggested by James, you will have to run the calculation to be sure.

--
Regards,

Cheney

LinkedIN @ http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b



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