With the release of eQUEST 3.63b we are given the option to model
Condensing Gas-Fired Boilers for hot water heating. However, domestic hot
water can still only be modeled by simplistic DW Heaters which have
options only for Electric, Gas, & Steam.
Would it make sense to just model the DHW loop as a HW loop with a process
load equal to the service hot water demand or is there some fundamental
reason why a hot water loop shouldn't be used as a domestic loop in
eQUEST?
Any input is appreciated. Thanks.
Robby Oylear, LEEDR AP
The only challenge I found in modeling DHW with a hot water loop was the
incoming water temperature being based on return water temperature,
however by adjusting the DT and supply temperature on the process load I
think I've approximated it properly.
I ran two loops, one a DHW loop and one a HW loop and found them to be
within 1% of each other. Then when I switched the HW boiler over to a
condensing boiler I found a 14% savings. Finally, to verify that the
condensing boiler was operating correctly, I increased the supply T so
that the return water temp would be around 110. After doing this the
results came within 1% of each other again.
Sounds like this is the way to go for modeling a condensing boiler for
DHW.
Robby Oylear, LEEDR AP
You can also define a condensing boiler curve for a DHW tank - HIR-FPLR
Chris Jones