E+ 25.1 HPWH simulations incorrect

[shorowit]

Issue overview

An IDF with a heat pump water heater (WaterHeater:HeatPump:WrappedCondenser and WaterHeater:Stratified) has new warnings and very different simulation results in E+ 25.1 vs 24.2.

Simulation results for Water Systems changed from 3.81 GJ (24.2) to 0.09 GJ (25.1).

Example warning in 25.1:

   ** Warning ** CalcEquipmentFlowRates: "DHW FIXTURES" - Target water temperature is greater than the hot water temperature by (29.06 C)
   **   ~~~   **  Environment=RUN PERIOD 1, at Simulation time=01/01 00:00 - 01:00
   **   ~~~   ** ...target water temperature     = 40.56 C
   **   ~~~   ** ...hot water temperature        = 11.50 C
   **   ~~~   ** ...Target water temperature should be less than or equal to the hot water temperature. Verify temperature setpoints and schedules.

I did not see this issue for IDFs with conventional storage water heaters (WaterHeater:Mixed). Sounds like it could be a unit conversion bug?

Operating System (Multiple choices)

Ubuntu

Operating System Version

24.04

Version of EnergyPlus

25.1 IO Freeze

Unmethours link or helpdesk ticket number

N/A

Defect file

in_24_2.idf.txt
in_25_1.idf.txt

[shorowit]

Hmm, it's apparently not HPWH specific. Here's an IDF using WaterHeater:Mixed where the Water Systems energy use is 0 GJ and there are new warnings in 25.1 like so:

   ** Warning ** CalcWaterThermalTankMixed: WaterHeater:Mixed = 'WATER HEATER':  Temperature of tank < 2C indicates of possibility of freeze. Tank Temperature = 0.25 C.
   **   ~~~   **  Environment=RUN PERIOD 1, at Simulation time=01/01 00:00 - 01:00

in_24_2.idf.txt
in_25_1.idf.txt