diff --git a/docs/source/workflow_inputs.rst b/docs/source/workflow_inputs.rst index 59cd94bc36..4e2849655c 100644 --- a/docs/source/workflow_inputs.rst +++ b/docs/source/workflow_inputs.rst @@ -1342,6 +1342,7 @@ Each heating system (other than a heat pump) is entered as an ``/HPXML/Building/ .. [#] Heating capacity autosized per ACCA Manual J/S based on heating design load. .. [#] The sum of all ``FractionHeatLoadServed`` (across all HVAC systems) must be less than or equal to 1. .. [#] FractionHeatLoadServed is required unless the heating system is a heat pump backup system (i.e., referenced by a ``HeatPump[BackupType="separate"]/BackupSystem``; see :ref:`hvac_heatpump`), in which case FractionHeatLoadServed is not allowed. + Heat pump backup will only operate during colder temperatures when the heat pump runs out of heating capacity or is disabled due to a switchover/lockout temperature. Electric Resistance ~~~~~~~~~~~~~~~~~~~ @@ -1745,6 +1746,7 @@ Each heat pump is entered as an ``/HPXML/Building/BuildingDetails/Systems/HVAC/H .. [#] HeatPumpType choices are "air-to-air", "mini-split", "ground-to-air", "water-loop-to-air", "packaged terminal heat pump", or "room air conditioner with reverse cycle". .. [#] HeatPumpFuel only choice is "electricity". .. [#] BackupType choices are "integrated" or "separate". + Heat pump backup will only operate during colder temperatures when the heat pump runs out of heating capacity or is disabled due to a switchover/lockout temperature. Use "integrated" if the heat pump's distribution system and blower fan power applies to the backup heating (e.g., built-in electric strip heat or an integrated backup furnace, i.e., a dual-fuel heat pump). Use "separate" if the backup system has its own distribution system (e.g., electric baseboard or a boiler). @@ -2678,7 +2680,12 @@ If the in-unit distribution system is specified as recirculation, additional inf ``PumpPower`` double W >= 0 No 50 [#]_ Recirculation pump power ================================= ======= ===== =========== ======== ======== ===================================== - .. [#] ControlType choices are "manual demand control", "presence sensor demand control", "temperature", "timer", or "no control". + .. [#] | ControlType choices are "manual demand control", "presence sensor demand control", "temperature", "timer", or "no control". + | - manual demand control: The pump only runs when a user presses a button indicating they are about to use hot water. + | - presence sensor demand control: The pump only runs when a sensor detects someone is present at the faucet. + | - temperature: The pump runs based on monitoring temperature at some point in the system. + | - timer: The pump is controlled by a timer. + | - no control: The pump runs continuously. .. [#] | If RecirculationPipingLoopLength not provided, calculated using the following equation from `ANSI/RESNET/ICC 301-2019 `_: | RecircPipeL = 2.0 * (2.0 * (CFA / NCfl)^0.5 + 10.0 * NCfl + 5.0 * Bsmnt) - 20.0 | where @@ -2771,6 +2778,8 @@ If not entered, the simulation will not include solar hot water. .. [#] SystemType only choice is "hot water". Solar hot water systems can be described with either simple or detailed inputs. +It is recommended to use detailed inputs and allow EnergyPlus to calculate the solar contribution to the hot water load; +the simple inputs are provided if equivalent calculations are performed in another software tool. Simple Inputs ~~~~~~~~~~~~~ @@ -2790,6 +2799,10 @@ To define a simple solar hot water system, additional information is entered in The referenced water heater cannot be a space-heating boiler nor attached to a desuperheater. .. [#] If ConnectedTo not provided, solar fraction will apply to all water heaters in the building. +.. warning:: + + The solar fraction will reduce the hot water load equally for every EnergyPlus timestep (even during nights and cloudy events). + Detailed Inputs ~~~~~~~~~~~~~~~