DesignBuilder ASHP with radiant surface - does not maintain the indoor setpoint in winter

asked 2025-03-13 08:53:34 -0500

updated 2025-03-13 10:50:59 -0500

Hello everyone,

I am simulating a wall radiant heating system with an air-to-water heat pump. Unfortunately, DesignBuilder only allows the air-to-water heat pump to be used for cooling, while for heating, I am forced to use the "ASHP Air-to-water Heat Pump. Water convector" template.

However, with this setup, I am unable to maintain the indoor temperature setpoint. I noticed that by significantly reducing the hot water storage tank (since it does not exist in reality), the heating coil provides thermal power only at the very beginning of the simulation, then gradually decreases to zero.

Has anyone experienced the same issue? I am available for any clarification.

Thank you in advance

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Comments

design builder has an air source HP heating object. Add a heat pump heating loop. change the type to 2- plant EIR and change the condenser to air source.

Greg Estep's avatar Greg Estep  ( 2025-03-13 12:16:53 -0500 )edit

Thank you very much for your response. I have added a Heat Pump Heating Plant Loop, but unfortunately, the heat pump's type option is not editable. By default, DesignBuilder forces me to use Type 1 - Equation Fit.

Giovanni Miracco's avatar Giovanni Miracco  ( 2025-03-14 03:30:31 -0500 )edit

what version of designbuilder are you using. The latest version allows this.

Greg Estep's avatar Greg Estep  ( 2025-03-14 13:19:11 -0500 )edit

It's 7.0.2.006 version

Giovanni Miracco's avatar Giovanni Miracco  ( 2025-03-17 06:03:19 -0500 )edit

I recommend downloading the latest version.

Greg Estep's avatar Greg Estep  ( 2025-03-17 08:06:00 -0500 )edit