[TRNSYS-users] Water Heater - Water Draw Forcing Function (variable)

[Thomas de Fresart]

I created a model for a water heating system and I currently use a Type14b
forcing function to set my water draws.  This forcing function takes the
variable water mains temperature from the weather input and forces the
mains water (tap water) into the water heater at a set schedule and rate.
 The problem I have with this is that now the water exiting the water
heater is fixed at the 120 degrees F from the water storage tank, and I
want to use a tempering valve and set the flow rate of the water to the
mixture of hot and cold water instead of just the hot water.

I'd like to use a Type11b tempering valve to mix the 120F hot water from
the tank with water from the mains (which varies in temperature) and output
water at a fixed 105F.  This means that the flow rate exiting the hot water
tank is less than the flow rate after the tempering valve, since some cold
water is added.  (water from the mains comes in both to the storage tank
and again to mix with the hot water exiting the storage tank)

Is there a way where I can use a forcing function to set the mixed hot/cold
water coming OUT of the tempering valve instead of using it to push water
into the storage tank from the mains.  The water temperature of the hot
water (in the tank) will be fixed at 120F, but the cold water from the
mains that mixes with the hot water from the tank will have a variable
temperature.  So, while the overall flow rate after the tempering valve
will be constant, the flow rate from each the hot water tank and the mains
will be variable since the mains temperatures change throughout the year.

The Type14b forcing function only allows me to 'push' water into the
storage tank, not 'pull' water out of the tempering valve after it has been
mixed with both hot and cold water.  Can you please suggest what forcing
function to use and in what order?

Thank you,
Tom



-- 
Tom
480-205-1228
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