Heating/Heat Rejection Equipment Controls

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Hi All-

I've come across a little problem and was hoping for some help. This
particular building has both a lake/well source heating/cooling and a hot
water boiler. The geothermal chiller is connected to a lake/well loop which
rejects heat to the ocean. However, for three months out of the year the
ocean water is too cold and the efficiency drops. Therefore we will be using
a hot water boiler to provide hot water during those three months. My
question lies with how to control the loops as to make this system work. I
have tried two ways around this and have failed at both.

1) Ideally, I would like to have two primary hot water loops connected to
the same secondary loop. This secondary loop would run to the hot water
coils. One primary loop would be fed from the boiler and one from the
chiller. This way I could use load management/equip controls to shut off
each loop on a schedule. However, we all know that equest does not allow for
two primary loops to feed one secondary loop.

2) I tried to have both the boiler and chiller connected to the same primary
hw loop. I successfully set up a heating equipment control to only have the
boiler run for three months. However the hot water loop controls do not
allow for a chiller to be controlled. So I tried to control both the hot
water loop AND the heat rejection loop. However, the type of loop that I am
using (lake/well loop) does not seem to be recognized as a heat rejection
loop (by the equipment controls). This seems puzzlilng to me. The controls
would like a WLHP loop instead of the lake/well loop. So again, I seem to be
stuck with no solution.

Any thoughts on how to solve this problem? Thanks for your help.


Steve Mignogna

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Joined: 2011-09-30
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