Balancing UFH

[vala]

We've now had our polished concrete floor installed and the required time has passed so we can now slowly introduce heat into it.

Thought I'd use this time to try and get the upstairs UFH working better, and try and mimic the way we hope to run an ASHP - all open loop, at one temp. Granted with the heat pump and WC the flow temp will vary but I haven't got that option with my oil combi.

What info do I need to have in order to balance the manifold and set the flow rates?

Wunda say just divide the loop length by 40 to get the flow rate. Tried this when the first floor UFH was installed and didn't really get anywhere.

I've come across another method which is to do with mass flow rate.

Has anyone here used this method and if so what info did you require from your own system to starting calculating the flow rate required.

FWIW - ground floor is 125mm concrete on top of 200mm PIR with 100mm pipe spacings. First floor is predominately carpet (1.9TOG for carpet and underlay combined) on top of 25/30mm pug mix on 100mm PIR with 135mm spacings.

Current flow temp is 25º and this is ok to increase at 1º a day as advised by the concrete installers.

[JohnMo]

At those spacing and if well insulated 25 to 28 will be all you need to flow at.

 

So do have mixer and pump as you are running an oil boiler?

 

1 hour ago, vala said:

Tried this when the first floor UFH was installed and didn't really get anywhere.

Not sure what you mean?

80m loop divided by 40 is 2L/min. You set the flow meter for that loop at 2 etc.

 

Start with the loops at the calculated flow rate. If all open loop you then have to tune the system. If rooms are to warm decrease the loop flow rate, if to cool increase flow rate.

[vala]

1 hour ago, JohnMo said:

At those spacing and if well insulated 25 to 28 will be all you need to flow at.

 

So do have mixer and pump as you are running an oil boiler?

 

Not sure what you mean?

80m loop divided by 40 is 2L/min. You set the flow meter for that loop at 2 etc.

 

Start with the loops at the calculated flow rate. If all open loop you then have to tune the system. If rooms are to warm decrease the loop flow rate, if to cool increase flow rate.

 

I have a mixer and pump as supplied by Wunda at present on both floors.

 

Initially when the first floor was installed all loops were set as per the guidelines by Wunda, so loop length divided by 40. All that I got was the same flow and return temp on the manifold and cold rooms.

Hence when I started looking into flow rates more I became aware of a different method using mass flow rate to determine the L/min required.