Open Studio: Gas-Fired DHW Loop

asked 2017-06-05 19:21:35 -0500

mcdonaa1's avatar

updated 2017-06-06 07:26:06 -0500

Open Studio: I am trying to model a gas-fired DHW loop.

The autosizing for a DHW loop does not work, as previously discussed here:

When I manually size my system, as it was concluded was the right thing to do, my values are off by an order of magnitude, and I am uncertain as to why. I am using default schedules created by NREL, and comparing my values to CEUS and RECs as well as utility bills. I get reasonable results when I reduce my manually sized values by an order of magnitude.

When I set my gas fired DHW water heater to 36000 BTU/h (10550 W), it yields: 126.23 MBtu But when I reduce it to 1055 W, it yields: 28.87 MBtu.

Yearly bills on the existing building place our annual gas consumption in a range of 25-34 MBTUs.

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Have you compared the assumptions for hot water demand and hot water temperature to reality? The water heater is only going to run as much as necessary to meet those loads.

aparker's avatar aparker  ( 2017-06-09 18:05:19 -0500 )edit