How to model an air to water heat pump?

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Thank you very much!!!! I will have a try for it in EnergyPlus. Since when I consulted someone, he said this system (AWHP) can only be built in EnergyPlus but not OpenStudio. And I am going to model it with the WaterHeater:HeatPump:PumpedCondenser object.

One question is that, do I need to include 2 HeatExchanger:FluidToFluid objects for the storage tank as it indirectly heats the radiators and DHW tank? And define the demand side as radiator/DHW, and supply side as the storage tank (Water heater)?

No HX:FluidtoFluid objects are required. The water will leave the storage tank on the supply side, then be split to flow through the radiator & DHW tank in parallel branches on the demand side. This is an "open" system where the water will be mixing between tanks instead of a "closed" system with WWHXs.

Thank you for the answers.

As this system is not drawn by me, but aren't there coils in the storage tank link to the radiators and DHW tank for exchanging heat to the water in the radaitors and DHW tank? And I have edited the post to include the loop the author created, that he mentioned to include two HX:FluidtoFluid objects.

Correct, if you wanted to have this as a "closed loop" with 2 HX:FluidtoFluid components then you will need the plant loops that you added to your post. Note that the HX:FluidtoFluid component needs water flow on both sides of the HX, which isn't technically what's happening. Water inside of the storage and DHW tanks are stagnant, so the HX effectiveness isn't quite the same. This is a small caveat, and the modeled plant loops should still work as intended.

So would you comment the system in the first image is not a practical system in real life? If not what should it looks like in real life. I am now very confused on the work flow of a real-life AWHP, please point out any mistakes in the following work flow: 1. HP heat the refrigerant by compressor and exchange the heat (in condenser) to water coming from storage tank, refrigerant cools and go back to evaporator again 2. Water go back to the storage tank, extracted from the tank and get distributed to their final heat emitters, or; 3. Water exchange the heat with DHW through coil

Hello, thank you for the answers. I will have a look on it.

But may I ask a very basic and primary question? Is it able to model the ASHP air to water heat pump model in EnergyPlus and its space heating system (water tank as water heater:mixed/stratified, radiators as ZoneHVAC:Baseboard:Convective: water, etc.) in a house with the existing Objects in EnergyPlus?

Because I am still very new to EnergyPlus and OpenStudio, I asked several people. Some say no. Some say yes, both can model the Air to water heat pump for space-heating, some say only EnergyPlus can model it. Thank you.