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Error when controling a Low Temperature Radiant Floor

asked 2016-08-18 08:46:24 -0600

Leopold Pujol's avatar

updated 2016-08-23 03:59:44 -0600

I'm doing a simulation for a heating floor system and cooling floor system.

To make this system, first I have assigned the Internal construction source on the floor of my building, after in the thermal zone I have assigned to each zone ZoneHVAC: Low Temperature Radiant: variable Flow, inside this option I assigning schedules thermostat, in the heating control temperature schedule name and cooling control temperature schedule name and put fractional Schedules of operation in the equipment. Next I’ve done two circuits Empty plant loop, one for the cooling circuit and other for the heating circuit assigning the Zone HVAC: Low Temperature Radiant: Variable Flow to the corresponding circuit, these circuits are formed to: variable pump + boiler/chiller and bypass piper + piper + Low Temperature Radiant: variable Flow + piper, I attached two images to make it more understandable this scheme

image description

In the set point manager of these circuits I have assigned the water outlet temperature, being these 15 degrees for the cooling and 35 degrees for the heating circuit with a tolerance of ± 1 degree.

The problem with this system is that when you go to the open result viewer is able to see that the temperature inside the building is not affected by the system.

I would appreciate any help or advice to solve my problem and apologize for my low level English.

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Can you provide a copy of your model? Also, did you set thermostats for each thermal zone?

mdahlhausen's avatar mdahlhausen  ( 2016-08-18 11:28:12 -0600 )edit

yes, I put a thermostat for each thermal zone and put the termostats in control temperature schedule name.

I attached my model in the following link:link text

Thanks for your help

Leopold Pujol's avatar Leopold Pujol  ( 2016-08-19 01:33:17 -0600 )edit

SO are you succeed in modeling a radiant floor heating system? I am trying to do it, but it is very difficult, would you please share a simple example? Thank you sosososo much!'s avatar  ( 2018-07-12 06:17:56 -0600 )edit

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answered 2016-08-22 12:39:16 -0600

updated 2016-08-22 18:13:31 -0600

The internal source construction object is built incorrectly: image description

Relevant EnergyPlus InputOutput Reference section: image description

You'll want to re-do your internal source construction and place a thin layer (< 2 inches or 0.05 meters) of mass material (concrete) as the inner most layer in your construction. Then specify the layer number. If your construction has 4 layers, you'll want to set the source layer as "3". (edit) You can do this in the App - if you scroll down in the Construction:InternalSource object in OpenStudio, you can set the source layer.

Another issue with your model is that the design temperatures for the radiant hot/cold water loops are very different from the operational setpoints. Your system is sized to run with a larger temperature difference than is supplied in operation. This will cause your system to be undersized. image description image description

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You can edit the 'Source Present After Layer' number in the OS App, at the internal source construction in the constructions tab. It's one of the fields underneath where the material layers are specified.

Sweet MSPaint skills, BTW! :)

ericringold's avatar ericringold  ( 2016-08-22 12:45:02 -0600 )edit

Thanks Eric! I never noticed I could scroll down on the Construction:Internal Source object and set this. Seems like I learned something from this question too.

mdahlhausen's avatar mdahlhausen  ( 2016-08-22 18:15:24 -0600 )edit

Thank you for your answer and analysis, in this moment the system complies with the standards of comfort.

Leopold Pujol's avatar Leopold Pujol  ( 2016-08-23 09:48:56 -0600 )edit

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Asked: 2016-08-18 08:46:24 -0600

Seen: 1,515 times

Last updated: Aug 23 '16