Hi, h
Has anyone come across issues with the chilled water pumps in the proposed and baseline building W/gpm being very different. It seems if you have a large building you will inherently have a high head so it doesn't seem right that the baseline uses 22W/gpm - equal to a pump operating against a 75 ft head, 65% combined impeller and motor efficiency. My building has 140 feet of secondary head and 50ft of primary head through the chiller plant which is 2,700 tons. This is 190ft of head giving me a primary of 15W/gpm and a secondary of 37W/gpm.
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
October 17, 2014 - 2:43 am
In large buildings there is possibly more errors in the design, but physically speaking larger fluid movers inherently become more efficient.
Also, from memory the requirement of 22W/gpm is for the sum of both primary and secondary pumps, i.e. the total W/gpm = total W / total gpm, right?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
October 23, 2014 - 11:08 am
Yes it is the sum of the two. ASHRAE clarified that because the language in the standard was not clear. LEED was allowing 22W/gpm for each before the clarification, so some projects would have been approved that way in the past.