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

Radiant Heating doesn't work

asked 2017-03-12 14:11:42 -0500

Shawn gravatar image

updated 2017-03-13 08:48:20 -0500


I am trying to install radiant floor in my simulation but I am having problems with that. (I only need the radiant floor during winter, for heating)

These ones are the steps that I've been following: 1. Assigned the Internal construction source on the floor of the house 2. In the thermal zone, I've assigned the ZoneHVAC: Low Temperature Radiant:VariableFlow 3. Completed the info inside this option. Heating Control temperature is on 18ºC and cooling in 50ª (don't want it to work) 4. The schedule of radiant floor is only in Winter Months. 5. I assigned the ZoneHVAC:LowTemperatureRadiant to an empy circuit. (Dind't assigned the cooling one) 6. When I run the simulation I don't get any temperature variation during winter months in the ResultsViewer. The house is still cold in winter.

I attached some pics. BTW.. How do I know between which layers (internal source constructions) are the pipes of the radiant floor?

image description image description image description image description image description image description

edit retag flag offensive close merge delete


What is your control temperature type? (mean indoor air temp, outdoor air temp, operative temp, or mean radiant temperature?) What climate are you running this in, and what are the internal temperatures you are hoping for?

Also, you should be able to see which layers the radiant tubes are between by exporting to EnergyPlus and looking up "Construction:InternalSource" to see after which layer the source is present.

DW gravatar imageDW ( 2017-03-13 10:39:51 -0500 )edit

1 answer

Sort by » oldest newest most voted

answered 2017-03-15 09:07:37 -0500

DW gravatar image

Right now, based on the order in your pictures, it looks like the model will use the ERV as the primary heating source. So, the radiant system may not even turn on if the model thinks it can handle the heating load with the ERV alone. If you want the radiant system to be the primary source, it must be placed first - or you can open the osm file in a text editor and change their priorities.

After that, you might want to make sure that you are getting some flow through your radiant floors by tracking some of the node flows and temperatures.

Lastly, the throttling range you have seems narrow, so your radiant system doesn't vary its flow much (It's on at full capacity below 17.5C and it's completely off above 18.5C). This means the radiant floor will not be on unless the control temperature starts dropping right down to 18. By the time this happens, there may be a large time delay before the radiant slab can raise the indoor temperature if that's what its control is based on. Consider widening the throttling range so that the radiant slab can begin combatting the heat loss from the space before the indoor temp drops below your setpoint.

Let me know if you're still having problems after trying the strategies above.

edit flag offensive delete link more


The order Shawn has is correct. The air terminal for any dedicated outdoor air system should always be first for zone hvac heating and cooling sequences. If it's not first, the terminal equipment won't see or be able to meet potential load added to the space by the DOAS unit. Additionally, the simulation will run better if the last item in the sequence is the equipment with the most control authority.

Adam Hilton gravatar imageAdam Hilton ( 2017-03-15 11:37:23 -0500 )edit

Your Answer

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

Add Answer


Question Tools

1 follower


Asked: 2017-03-12 14:11:42 -0500

Seen: 76 times

Last updated: Mar 15