Determining ABV setting from min flow rate / pump curves etc

[tommcdonna]

Vaillant 428 - Min flow required approx 20 litres/min (0.33 litres/sec or 1200kg/h)

Pump Grundfoss Selectric 15/50 (set at III) - Pump curve here: http://www.plumbnation.co.uk/site/g...ump/Grundfos UPS Selectric Pumps Brochure.pdf

ABV Honeywell DU144 - Curve here: http://products.ecc.emea.honeywell.com/europe/pdf/du144-pd-en0h2706ge25r1208.pdf

If I've got the theory right, the min pump flow puts the head/pressure at around 3.3m, approx 32kpa (or 320mbar) on the Grundfoss chart.

32mbar head and 1200kg/h flow on the Honeywell chart would look to me to be about 0.08.

So from that, theoretically this setup above the ABV should be set wound pretty much all the way out (scale of 0.1 - 0.6).

Have I got that right?

 

[tommcdonna]

Anyone?

 

[D_Hailsham]

So from that, theoretically this setup above the ABV should be set wound pretty much all the way out (scale of 0.1 - 0.6).

Have I got that right?

Yes. But that's just the starting point; you may need to fine tune it.

With all rads fully open and system up to temperature, check that there is no flow through the valve by feeling the pipe on the exit from the valve. If there is, close the ABV slightly until it stops.

Now close down one rad and check that the pipe has started to warm up.