viessmann setting min and max pump rates

[monkeysballs]

so i have a 30kw vitodens 200w b2kf
i am trying to figure out how i should have the pump configured for the min and max pump rates

its currently set to 40%/60%
the bits from the instructions are here
im running really low flow temps and therefore dont need huge amounts of flow. the system has been fitted with automatic balancing valves (danfoss ras-c2) that have been pre set to get the correct output from the emitters

#

 

[Swwils]

Do you live in a hotel?

 

[monkeysballs]

Lol no why?

 

[Swwils]

30kw, auto balancing valves...

 

[monkeysballs]

30kw for dhw production 17lpm
Autovalves ,why not it's not like they are expensive.
I have low heat requirements I'm running 35c at 0 and and about 36 at -2/3 so the glow through some of the rads is tiny! Even the largest ones don't need big flow

 

[Swwils]

Your boilers pump targets both pressure and speed, youve stuck on a valve designed to give a set flow rate no matter what the dp is either side of the valve. Hence it is pressure independent. When you get a faster flow from the boiler you will ALWAYS have a higher dp. Dp and flow rate are intrinsically linked.

AKA you won't see any benefits over standard balancing and will have increased system resistance.

 

[monkeysballs]

So I should swap it to fixed speed then apparently it can for low Loss headers etc

 

[monkeysballs]

The valves were specified by the installer I'd have happily just had high accuracy flow limiting valves rather than load balancing if it would have worked better