UFH Flow rate Pump query

[john0wingnut]

Hi all

 

Im after a bit of a sense check on  my UFH system pump setup / flow rate.

 

System:

ASHP is a 12kw Nibe F2040. SMO 20 controller

100L Buffer, plumbed as a 3 port.

Wilo Yonos PARA pump with max 6m head supplying 2x manifolds.

175 sqm of UFH slab

17 loops, now fully de-zoned

 

Heatloss from my calcs is 8.3kw at -3/20 dT5

 

Flow rate would thus be 1.41m3/hr or 23.6l/min

 

I fully opened all the flow meters on all 17 loops, put the Wilo pump on max and then totalled all the flow rates up on each flow meter and got a total of 34l/min, which i then converted to 2.04m3/hr. Reading that max flow rate off of the Wilo Yonos Constant pressure pump graph at max setting gives a head of 3.5.

 

https://www.ufht.co.uk/wp-content/uploads/2018/03/yonos-manual.pdf page 14

 

I then put the red dial on constant pressure no. 3 and got a total of 24.7l/min

 

Is this then the correct setting for the UFH pump?

 

Many thanks

John

[ProDave]

I suspect most of us (well me at least) just start on the mid speed of the pump, and if it all works well, slow the pump down.  My aim was to run the pump at the slowest setting (quietest) that would deliver the required heat to the house.  Having first changed the cheap noisy pump for a Wilo.

[john0wingnut]

3 minutes ago, ProDave said:

I suspect most of us (well me at least) just start on the mid speed of the pump, and if it all works well, slow the pump down.  My aim was to run the pump at the slowest setting (quietest) that would deliver the required heat to the house.  Having first changed the cheap noisy pump for a Wilo.

 

Excellent. So I am on the right track. Currently on setting 3, it is very quiet. If I put it on 6 it makes an awful humming / whine sound

[JohnMo]

I basically set the flow rates for each loop based on its length and when running the pump set at the lowest setting that could make the flow rates required. Once everything was up and running tweek the rates up or down based on room temperature, too cool increase too hot decrease flow rate.

[john0wingnut]

I’ve got the flows to a good point now. 2 rooms slightly higher than others, so will adjust down slightly, but others all at within .3 degs of each other. Im am also slowly adjusting the WC curve down, as most rooms still too warm.