Noisy system, pump speed?

[whistler]

Moved into a bungalow a few years ago which had a Vaillant Turbomax 824, which as a 24kw output. The system has always been noisy when it fires up, mainly pipework noises I think. Have asked service engineers about this but never got a solution. Whilst browsing the boiler manual I noticed it said that if system is noisy, pump speed can be reduced from the default position III to position II. I tried this and now the noises seem to have disappeared!!!

Out of curiosity I did a rough calculation of the heat requirements of the house and it came to about 10kw, less than half the o/p of the boiler. As the property is a bungalow, there is no 'lift' required from the pump, so it seems logical to me that the pump has been set to high, resulting in the noise.

Does this all make sense ? Is it a good idea to reduce the pump speed ? Although the heating is performing adequately now, will I see a difference in the depths of winter?

 

[Agile]

The "normal" pump setting is "2".

"3" is only required for testing and purging air from the system. It is sometimes used to overcome installation faults or partial blockages.

"1" can be used in small properties but not so advisable except with a DIY owner as the reduced starting torque makes it prone to sticking on cold starts.

Tony Glazier

 

[whistler]

There are only two settings on the pump marked III and II.
Extract from the manual:-

8.4 Adjusting pump speed
The unit is fitted with a two-speed pump. The pump is
delivered with the switch (1) set to position III (Fig. 8.4.).
Attention!
Important note:
The boiler should only be operated at pump
setting III because the heating capacity for hot
water is reduced when operated at pump
setting II!
It is possible, however, to change the pump setting from
Level III to Level II manually when there is noise coming
from the heating system.