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Is there an "unmet hours" output variable equivalent for DHW demand?

asked 2016-01-27 04:37:49 -0500

updated 2016-01-27 08:01:19 -0500

If we want to see if our heating/cooling system is adequately-sized we can use the Facility Heating Setpoint Not Met While Occupied Time (i.e. unmet hours) output variable. Is there anything similar which can tell us if our domestic hot water demand is not being met?

Alternatively (since I can't see anything obvious), what would be a simple calculation from outputs which are available?

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answered 2016-01-27 06:23:39 -0500

Archmage's avatar

I cannot think of a time-based output, but the output variable called "Water Use Connections Hot Water Temperature" should be compared to the intended hot water supply temperature setpoint.

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I thought that might be the answer. I was actually about to post it myself, hence the slight change to the question. Beat me to it!

Jamie Bull's avatar Jamie Bull  ( 2016-01-27 06:26:20 -0500 )edit

answered 2016-01-27 06:42:00 -0500

If your WaterUse:Connections is the only thing on the demand side of your plant loop, or you can safely assume the rest is satisfied, then you can use the Plant Loop Unmet demand rates:

HVAC,Average,Plant Supply Side Unmet Demand Rate [W]
HVAC,Average,Plant Supply Side Not Distributed Demand Rate [W]

See documentation here

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Asked: 2016-01-27 04:37:49 -0500

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Last updated: Jan 27 '16