First time here? Check out the Help page!

Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question
2

Can't get Boiler:HotWater to heat water

asked 10 years ago

LSurf's avatar

updated 7 years ago

I have a working model built from some EnergyPlus example files.

In my PlantLoop for heating I have a Storage Tank for preheating, and a WaterHeater:Mixed to provide additional heat. I want to compare this scenario with my baseline scenario, in which I have a Boiler:HotWater for heating.

For this purpose I'm trying to replace the WaterHeater by a Boiler. However, I can't get this to work. I suspect some issue with setpoints, since there is flow through the Boiler, it just doesn't heat. Also, the WaterHeater has a field called Setpoint Temperature Schedule Name, whereas the Boiler doesn't.

I tried fiddling around with the setpoints. Also I've moved the Boiler to the same branch as the Storage Tank, without result.

How can I get my Boiler to heat to 50 °C?

Working with WaterHeater:Mixed

Not working with Boiler:HotWater

Full folder

The problem is with the the second loop in this HVAC system diagram.

HVAC system

Preview: (hide)

Comments

1

do you have an operation scheme for the boiler?

Archmage's avatar Archmage  ( 10 years ago )

@Archmerage I think I have those correctly set up, but I'm not sure. I have these in my idf-file

LSurf's avatar LSurf  ( 10 years ago )
1

You have PlantEquipmentOperation:HeatingLoad. You may find that PlantEquipmentOperation:ComponentSetpoint is what you need though I've not tested it on your file. See the comments on this answer.

Jamie Bull's avatar Jamie Bull  ( 10 years ago )

Awesome Jamie, that did the trick! I guess I'll have to learn more about the Operation scheme's. Can you convert your comment to an answer?

LSurf's avatar LSurf  ( 10 years ago )

1 Answer

Sort by » oldest newest most voted
2

answered 10 years ago

updated 10 years ago

As was also suggested by @Archmage, the problem lies with your operation scheme. Having had a similar problem recently with two water heaters on the same loop, the problem should be solved by adding a PlantEquipmentOperation:ComponentSetpoint object for the loop rather than the PlantEquipmentOperation:HeatingLoad you currently have.

I'm not at all clear on why this is the case. That is, why a PlantEquipmentOperation:HeatingLoad scheme controlling multiple plant items in a PlantEquipmentList doesn't work. There doesn't seem to be anything explaining this in the documentation and I've seem odd behaviour at times so I'd be interested in a more comprehensive answer that gives the reasoning/logic behind it.

For reference, here's the section in the docs about plant and condenser control, though to me it's not clear how to work out the issue from reading it.

Preview: (hide)
link

Comments

1

Hi, I am having the reverse problem, when I use PlantEquipmentOperation:ComponentSetpoint on a plant loop with two boilers it doesn't work (ie the boilers don't turn on and I have zero flow) but when I use PlantEquipmentOperation:HeatingLoad it does work. Have you seen this before as well? My problem is I have to use OpenStudio and I can't find an option to change the operation scheme.

Annie Marston's avatar Annie Marston  ( 9 years ago )

I haven't seen this, and don't use OpenStudio. If you're still having problems you might try opening a new question.

Jamie Bull's avatar Jamie Bull  ( 9 years ago )

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Training Workshops

Careers

Question Tools

1 follower

Stats

Asked: 10 years ago

Seen: 430 times

Last updated: Feb 26 '15