VRF Condenser Loop with Heat Injection

Help and discussion on using the Detailed HVAC option

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Posts: 3

VRF Condenser Loop with Heat Injection

Postby NirajP_GIW » Wed May 17, 2017 8:16 am


I am working on a project were a VRF system has been specified with a cooling condenser water loop system. I can model this easily enough in DesignBuilder (v5.03.007).

However, for winter operation, the cooling condenser water loop also includes a water heater for heat injection to prevent the loop temperature from dropping too low.

Is there a way to include heating for the condenser water loop? If not, is there an alternative way that the above system can be modelled e.g. with a gas fired basin heater?

Posts: 6

Re: VRF Condenser Loop with Heat Injection

Postby olafdybinski » Fri Dec 01, 2017 9:49 am

did you find a solution for your problem? I am having quite similar problem at the moment.

Best regards,
Posts: 5

Re: VRF Condenser Loop with Heat Injection

Postby msweeney0312 » Fri Mar 09, 2018 3:53 pm

You can put a Loop-to-Loop Heat Exchanger on the Supply side of your Condenser Water Loop (parallel to the cooling tower), and connect the other side of the heat exchanger to a Hot Water Loop. Set the heat exchanger's operation to "Heating Setpoint Modulated", and place a setpoint manager equal to your heat injection setpoint directly at the outlet of the heat exchanger into the condenser loop.
WithWIthoutInjection.JPG (115.25 KiB) Viewed 4976 times

Heat Injection Loop.JPG
Heat Injection Loop.JPG (77.08 KiB) Viewed 4976 times
Posts: 11

Re: VRF Condenser Loop with Heat Injection

Postby e.duff » Tue May 21, 2019 2:13 am


I am looking to create the same system as OP. Can this be achieved in v4.7?

Also, is there any way to view the images from the previous post? For some reason they won't show...

Thanks all.

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