[Equest-users] 90.1-2007 Table 7.8 Water Heater Efficiencies

Paul Diglio paul.diglio at sbcglobal.net
Tue Oct 4 04:37:07 PDT 2011

Could anyone help me understand the calculation for the minimum efficiency of 
gas storage water heaters per the table above?

The calculation is 80%Et (Q/800+110 SqRt V) SL, Btuh.

I understand that Q is the nameplate input rate in Btuh and V is the volume.

Do I use the volume of the whole system, the storage tank only or the recovery 
rate volume?

I understand SL is the standby loss.  Does SL, Btuh mean multiply the equation 
in parenthesis by the standby loss in btu's per hour?

Thanks for the help,

Paul Diglio
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20111004/90db6fa0/attachment.htm>

More information about the Equest-users mailing list