How to set defined water difference pressure for circuit pump - Vitodens 200-W B2HB 24KW

[karel_cz]

Hello,sometimes when my boiler start heating in the early morning i can hear nastily noice - whistling from termostatic valve of radiators. Its becouse hot water incoming to radiators have to much pressure to the termostatic valve when is near closing.

So my questios is : Can Set in my Vitodens 200-W B2HB set constant diffence of water pressure? It menas the constant difference water pressure output from boiler and pressure going back to boiler.

Becouse now noise behavior seem that when termostatic valve is near closing, then waterr pressure difference is getting to much high.

[Patrick_Zarges]

Hey karel_cz,

you can set the speed of the internal circulation pump in coding level 2 >> Code 31.
It's adjustable from 0 to 100%

But it's only possible when the pump is operaded as boiler circuit pump.

°pa

[karel_cz]

Hello Patrick,
Can I replace included circuit pump with some better pump which has capability of control difference water pressure and respect Viessmann guarantee?

For example circuit pump Wilo Yonos PICO 25/1-4 can handle this functionality.

[Patrick_Zarges]

You can't use any other pump as the UPM3 15-75. In the delivered condition the minimum pump rate (coding address"E7") and the maximum pump rate (coding address "E6") are set to the following values:

Min. pump rate 45
Max. pump rate 80

Is it possible to change this address? Maybe there are some differences between the german and your B2HB. In the service manual for England, E6 and E7 aren't listed.

°pa