Heat Output Data - Biscuit Screed / Pug Mix

[OzWald]

Hi All,

 

I have been recommended, anecdotally, that UFH pipes laid in a biscuit screed / pug mix for my 1st floor (suspended) will be 'better' than aluminium spreader plates, however, and as an engineer, I'm much more comfortable when talking about numbers...

 

I'm struggling to find heat output data for UFH pipes laid in a biscuit screed / pug mix. The only source I have found is a datasheet on Continal's website, but the variables are fixed at 55-60C flow temperature and 1tog of insulation above.

 

Has anyone come across a data table (or calculator) that shows other heat outputs for between-joist pug mix for different variables? - I'm interested, particularly, in heat output values for 35C flow temperature with 1.5tog (which I believe is approximately equivalent to 15mm pine floorboards).

 

Many thanks,

 

Oz

[ProDave]

No data, but I can confirm our main floor downstairs, UFH in a pug mix is better at heating the rooms than the utility room that has UFH pipes and spreader plate, all running at the same temperature.

[saveasteading]

Energy in equals energy out.

So what is the difference? I shall try. In no particular order.

 

I don't think they are (can be) more or less efficient, but behave differently.

With pug the material absorbs heat before heating the room, so there is more energy stored in the room.

When the door or window opens, the warm air escapes from both scenarios, but the warmed floor remains.

When the heat source is off, the pug continues to warm feet and lower body, and the room.

The pug allows the system to run at lower input temperatures/ offpeak for longer, perhaps with the feed at the lowest and most efficient, temperature.

 

I look forward to any conflicting or additional thoughts.

[ProDave]

3 minutes ago, saveasteading said:

Energy in equals energy out.

So what is the difference? I shall try. In no particular order.

My finding is definitely the room with spreader plates heats the room less well.

 

So for a given UFH flow temperature, less heat goes into the room.  So that must mean, if I cared to measure it, the return temperature from that loop would be higher than from the rooms with the pug mix, so less energy has gone into that room.

 

Pug mix is cheap and easy, you just need to make sure you size the joists for the extra dead load they have to support.