RE: [EnergyPlus_Support] Problem with pumps

You have drawn a diagram based on your idea of a system, without considering what are the components available to construct such a system in real world.

Where is you domestic water input, for example. What is the heating source and storage? Do you have a storage tank? Is it a inline water heater? ETC.

If you have an IDF for your schematic diagram, please send it to me. If not. I have no idea what is in your system.

If you have a real system, will it be implemented in that way. How to reduce the temperature at 80°C to 65°C by heating? If it is an inline heater, the DHW supply is not part of the plant loop, unless you mix the tank water with the water main cold water.

Do you have a pump for each of your shower room?

Dear Dr. Li,

Thank you for the suggested solution. I found the diagram but I think that it is for different system than the one I have and if I use it then the components won't be sized correctly.

I've prepared and attached a new scheme, which I think gives a better illustration of the system that I need to model.

Basically there is a diesel boiler that supplies all the heat for heating and domestic water use for two zones. The I/O temperatures of the heating system will be 80/60 oC.

The tempearture of the DHW will be 65 oC and will be achieved through indirect heating in a water heater (for each zone), using the water from the boiler (80 oC).

(Input 80°C and output 65°C by heating.)

My original idea was to model each branch after the splitter as a separate demand, but the main problem occured that there are pumps after the splitter. And EnergyPlus says they can't be there. (Error messages?)

Moreover, the water heaters also must be on the supply side and probably this would generate another error message. I understand that I have to somehow model all the splitter outlet branches including the pumps and water heaters as supply ones but for now I can't find a way to do that. Any help would be highly appreciated!

Read and run the examples in the Getting Started Document.

The solar collector example is the nearest model.

Best regards!

Lyuben

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: Linda Lawrie <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Mon, February 14, 2011 11:46:18 PM
Subject: RE: [EnergyPlus_Support] Problem with pumps

What you have shown are not complete demand loop, supply loops, etc. as described in the EPlus I/O manual and examples.

One boiler tank to supply all the demand is one plant loop. Look up the water heater tank object to see how the branches should be connected. The tank can be gas or electric heated, or puchased hot water. This is the supply side of the tank, which may have a pump.

The domestic main supply is connected to the tank use side loop which may have a pump, which is used as a control valve for domestic water intake.

DHW and radiant panels are all demand loop branches one one heater tank loop.

Bypass branch should be provided so that tank water can be circulated (pump) to maintain the temperature to the tank setpoint value, when there is no demand.

Draw a complete diagram with splitter and mixer and all the branches, and the domestic main water supply and the DWH water tempering valve, you will then have a better idea of the system. There is such a diagram in the I/O Ref. Manual.

Without looking at your IDF, I have no idea how you are simulating your system.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: lbarosow@xxxxxxxxx
Date: Mon, 14 Feb 2011 03:32:14 -0800
Subject: [EnergyPlus_Support] Problem with pumps

Hello Everyone,

I am trying to model a Radiator Heating system and I have a problem with the pumps. I've attached a scheme for more clearance. The water from the boiler is transported through a circulation pump (pump 1 on the scheme) and then distributed to four consumers, each on a separate branch. Each of these branches also has a circulation pump (pumps 2, 3, 4 and 5). When I try to model this exact situation in E+, the following error is being generated;

** An active component should not be present in the first branch in conjunction with branch pumps

** Current version does not support Loop pumps and branch pumps together

How should I proceed in this case? Should I remove the pumps 2, 3, 4 and 5 which are on the branches, or is it better to remove pump 1 and leave the rest? Or is there some other way to solve this and how would it reflect on the energy consumption?

Thank you!

Lyuben

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