RE: [EnergyPlus_Support] water heater

Change the 1000000 Watt to 90000 watt or smaller in the HeatingLoad object.

The tank temperature in the simulation may change in the 10 minute interval.
========================

Sediment in the water is only in the DHW tank. The DHW tank has drain pipel You clean as often as you like. It does not effect the boiler.

The water in the HW tank should be filtered and clean and is not affected by usage. Have you heard of de-ionized water?

There is a conduction to the environment field, I am not sure whether it is in your choice below. In a boiler, the efficiency fields covers this loss.

PLR cannot be larger than Unity. If PLR is 1, your gas fire will not turn off.

The DHW tank has a lower temperature because the hot water pipe is not fully insulated, and it is connected to the cold water main. (See the diagram attached.)

Gas fire ignition delay may have nothing to do with your temperature. The tank thermostat will then turn on the starting signal first, the gas pilot will light, and then the main fire comes on. Energy Plus does not simulate the ignition delay. It is a only few second. The time step at 6 is ten minutes interval.

The 81 in the boiler design temperature means that the boiler will be operating at this temperature, on and off with a few degree difference. If you change this number the tank temperature or the loop temperature should change. Of cource, if you have other objects to control this, then it may not have effect.

Because the node names are different, I do not know which one is working.

The DHW control is on the second loop. It is not controlled, as you have a mixer on the tap. If you want to control this temperature, it can be added. It is called the tempering valve object.

You can monitor the tank water temperature change in the real system. However, you cannot change the real system temperature with the sensors.

You are a Master of ME and should know all these.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: t.t111ir@xxxxxxxxx
Date: Sat, 18 Feb 2012 20:48:44 +0000
Subject: Re: [EnergyPlus_Support] water heater

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: EnergyPlus_Support <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Saturday, February 18, 2012 11:37 PM
Subject: RE: [EnergyPlus_Support] water heater

All your real equipment are in the simulation. There are warnings on building, etc.

The following is the water tank portion of the boiler.

you say it is the tank portion of the boiler?ok you mean boiler has tank for storage hot water ok? in my building there is tank in boiler and thermostat ,

but i want to examine dely ignation of heater in boiler , my professor say when tank water of boiler is smaller than 80C then boiler will be on but it has delay (ignation delay) does enegyplus examine ignation delay? and also my porfessor say examine the effect of U factor of boiler it means when it is clean,when its wall has sediment , but i dont know how i can examin it in energyplus?

Boiler:HotWater,

Central Boiler, !- Name

NaturalGas, !- Fuel Type

autosize, !- Nominal Capacity {W}

0.8, !- Nominal Thermal Efficiency

LeavingBoiler, !- Efficiency Curve Temperature Evaluation Variable

, !- Normalized Boiler Efficiency Curve Name

81., !- Design Water Outlet Temperature {C} (This is the build in thermostat) you mean it is thermostat it mean when outlet water temperature greater than 81 boiler will be off?

autosize, !- Design Water Flow Rate {m3/s}

0.0, !- Minimum Part Load Ratio

1.2, !- Maximum Part Load Ratio (Did you put this in?) yes i put this , this is my idf, but i want boiler work on with it maximum capacity it means when boiler work with full capacity with it ons , but i dont know how i can do it?

1.0, !- Optimum Part Load Ratio

Central Boiler inlet Node, !- Boiler Water Inlet Node Name

Central Boiler Outlet Node, !- Boiler Water Outlet Node Name

100., !- Water Outlet Upper Temperature Limit {C} Safety temperature

ConstantFlow; !- Boiler Flow Mode

Because you define it as a natural gas boiler, the heat required will calculated in terms of the cost of gas supply in the report.

Because it is constantFlow the efficiency curve may not apply. You need to check.

The temperature leaving boiler is also an option. You need to read and check. I do not know.
======================
PlantLoop,

Hot Water Loop, !- Name

Water, !- Fluid Type

, !- User Defined Fluid Type

Hot Loop Operation, !- Plant Equipment Operation Scheme Name

HW Supply Outlet Node, !- Loop Temperature Setpoint Node Name

100, !- Maximum Loop Temperature {C}

10, !- Minimum Loop Temperature {C}

autosize, !- Maximum Loop Flow Rate {m3/s}

0.0, !- Minimum Loop Flow Rate {m3/s}

autocalculate, !- Plant Loop Volume {m3}

HW Supply Inlet Node, !- Plant Side Inlet Node Name

HW Supply Outlet Node, !- Plant Side Outlet Node Name

Heating Supply Side Branches, !- Plant Side Branch List Name

Heating Supply Side Connectors, !- Plant Side Connector List Name

HW Demand Inlet Node, !- Demand Side Inlet Node Name

HW Demand Outlet Node, !- Demand Side Outlet Node Name

Heating Demand Side Branches, !- Demand Side Branch List Name

Heating Demand Side Connectors, !- Demand Side Connector List Name

Sequential; !- Load Distribution Scheme

This described the whole loop plant system for HW supply. The radiators and the DHW tank are connected to this loop.
=====================
PlantEquipmentList,

heating plant, !- Name

Boiler:HotWater, !- Equipment 1 Object Type

Central Boiler; !- Equipment 1 Name

Only one boiler is defined. This the furnace part of the real system which has the water jacket to heat the HW.

===================

PlantEquipmentOperation:HeatingLoad,
Central Boiler Only, !- Name
0, !- Load Range 1 Lower Limit {W}
1000000, !- Load Range 1 Upper Limit {W}
heating plant; !- Range 1 Equipment List Name

This is where specify the size of the fire. One million watt is used here. A household gas heater is arouond 90kW for a 60 gallon tank.

===================

PlantEquipmentOperationSchemes,
Hot Loop Operation, !- Name
PlantEquipmentOperation:HeatingLoad, !- Control Scheme 1 Object Type
Central Boiler Only, !- Control Scheme 1 Name
PlantOnSched; !- Control Scheme 1 Schedule Name

This is where shut the boiler off in Summer, if you want.

=======================

ã??
!- =========== ALL OBJECTS IN CLASS: AVAILABILITYMANAGER:HIGHTEMPERATURETURNOFF ===========
AvailabilityManager:HighTemperatureTurnOff,
schedual boiler, !- Name
Central Boiler Outlet Node, !- Sensor Node Name
82; !- Temperature {C}
ã??
!- =========== ALL OBJECTS IN CLASS: AVAILABILITYMANAGER:LOWTEMPERATURETURNON ===========
AvailabilityManager:LowTemperatureTurnOn,
schedule boiler 2, !- Name
Central Boiler Outlet Node, !- Sensor Node Name
80; !- Temperature {C}

!- =============================

SetpointManager:Scheduled,
Hot Water Loop Setpoint Manager, !- Name
Temperature, !- Control Variable
HW Loop Temp Schedule, !- Schedule Name
HW Supply Outlet Node; !- Setpoint Node or NodeList Name

You added these two objects in because you wanted to control the furnace to turn on and off at these temperatures. I told you that I am not check all the node names.

Normally, the set point manager alone is sufficient.

Dr.Li ,

when mass flow rate of HW PUMP is zero then gas consumption of boiler is zero too? but in my building sometimes pump will off and boiler will work it means there is no mass flow rate but heater of boiler is on ,

====================

there is one sensor in inlet of pump if it is smaller that 63 thern mass flow rate of pump will be on and if greater than of 63 mass flow rate of pump will be off , but when pump will be off on the boiler there is water and mybye its temperature smaller than 80 so burner of boiler is on , but i cant model this in energyplus because when mass flow rate in boiler is zero the boile consumption is zero ( q= m*c difference temperature,) but in real system maybe on time mass flow rate is zero but burner of boiler is on , but i dont how i can show this? could you help in doing it ?

The 65Â°C pipe is on another loop the DHW loop.

but Dr.Li the coil that in my real building doesn have setpoint managger for domostic hot water , only boiler has thermostat ,

You cannot use the low temperature radiant panel model to simulate your system.

You do not have a air loop system. The coil is in the DHW tank. You may have an heater in the DHW tank which is not shown in your schematic. there is no heater in DHW , it makes domostic hot water with hot water that comes from boiler,

The thermometer on the furnace is for temperature indication. A safety valve will be a whistle when the furnace temperature reaches the boiling point. The model of radiator in EPlus is the one you have.

I am a retired EE Proffessor, yes. (Universities in Kuala Lumpur, Malaysia 1969, Toronto, and Polytechnics in Singapore 1996.) I stopped over in Tehran in 1953.

realy ? i study MSC mechanical engeering at Polytechnics in tehran and i m intrested in applying for PHD,

i m very happly that ou were in tehran :)

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: t.t111ir@xxxxxxxxx
Date: Sat, 18 Feb 2012 18:56:01 +0000
Subject: Re: [EnergyPlus_Support] water heater

From: Tooran T <t.t111ir@xxxxxxxxx>
To: "EnergyPlus_Support@xxxxxxxxxxxxxxx" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Saturday, February 18, 2012 10:23 PM
Subject: Re: [EnergyPlus_Support] water heater

Dear Dr.Li , i think i cant say my problem in english :(

Dr.Li ,

i have building that there is tank that there is gas natural heater and heat water and then this water circulate to both radiator and coil , in the coil this hot water exchange heat to domostic water and make hot domostic water ,

i think at first i do wrong i use boiler in HW loop and water heater in DHW , but in my building there is only water heater and coil ,
when i read document of energy plus i think i must use water heater that heat water for both radiator and coil and zone:hvac:low temperature radiant constant flow (for simulating radiator )

i hope i can say my problem correctly in english

by the way Dr.Li do you teach at university?

nice too meet you Dr.Li

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: EnergyPlus_Support <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Saturday, February 18, 2012 9:56 PM
Subject: RE: [EnergyPlus_Support] water heater

See reply in Blue background.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: t.t111ir@xxxxxxxxx
Date: Sat, 18 Feb 2012 14:39:08 +0000
Subject: Re: [EnergyPlus_Support] water heater

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: EnergyPlus_Support <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Saturday, February 18, 2012 4:47 PM
Subject: RE: [EnergyPlus_Support] water heater

For T.t: If you are referring to the same project. The answer is yes and no.

Dear Dr.Li

the building that i have modeled there is boiler that has tank ,how can i simulate it? i think the boiler onject in energyplus there is no tank ,

if it is right how i can simulate this?

HW loop is a class in the program. water heater is an object in a class.

The radiators are branch objects connected to the HW loop and not to a water heater, but may be a water heater tank. what you mean by may be a water heater tank? As I said before, you have to use the name and meaning of EPlus.

Radiator is a the same as a water coil, but it radiates heat in a Zone directly. It is branch of the water loop and is therefore part of the loop as a water heater tank.

Heater is the fire, the heating source, the heating element.

There are many water heater types, electric, gas, oil, etc. It is a boiler in the HW Plant Loop.

Water heater tank is a storage tank, (and need not have any volume, instantaneous tank.)
you mean when tank voulme is zero then it is tankless ( instantaneous tank) and if its tank volume is not zero then it is storage tank?

I am sure you have seen a small electric water heater which can be connected in line with a shower. The element is immersed in water, but the water volume is so small, the water flowing through the pipe is heated up instantaneously. As soon as the water stops, the element is switched off. You can also set a maximum temperatur.To simulate this, you use a tank with very small volume.

ALL OBJECTS IN CLASS: WATERHEATER:MIXED ===========

WaterHeater:Mixed,
Indirect Water Heater, !- Name
AUTOSIZE, !- Tank Volume {m3}

Leave it as autosized, as you do not know the size of the tank nor the furnace. After the simulation, you can find the size used from the .EIO file.

if i put zero in tank volume , then water heater will be with out tank storage, yes? May be zero is too small, as it must wrap around the electric heater.

That is why I suggested that you need to learn the names from the EPlus manual and not from the Wiki link.

The DHW tank can be part of the same HW loop, to get the heat source from one boiler, but the water is not in the same HW loop, because the hot water loop for radiator does not want to be connected to the water main water.

HW is a closed loop. The water is circulated to the coils, radiators, and heating coils.

In DHW (domestic HW) the inlet to the tank is the water main cold water the outlet is to the tap and used and then to the drain (sewer). The EPlus objects are different for the shows, etc.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: t.t111ir@xxxxxxxxx
Date: Sat, 18 Feb 2012 10:30:00 +0000
Subject: [EnergyPlus_Support] water heater

can i use water heater to inculde hot water for radiator ?

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