Combi boiler pumps

mth

Joined
12 Nov 2008
Messages
14
Reaction score
0
Location
Derbyshire
Country
United Kingdom
Hi

My combi has two pumps in. In the manual, it says one is DHW and one is for heating.

They are both Grundfos 20/60 with adjustable speed settings of 1-3.

By default they were both set to 3. I changed the central heating one down to 1 as it sounded like a jet engine inside the house with the water rushing around my pipes!

What does the DHW pump actually do? What affect will changing the speed on this have? The speed at which the water comes out the hot tap is determined by the pressure of mains - correct? So does this pump move the water through the heat exchanger at different speeds?

Thanks.
 
Sponsored Links
Sounds like something out of Greek mithology!

The DHW pump should be on max to put the heat into the DHW.

Ther CH one would usually be on 2 but if 1 still gives enough heat then thats OK. The temperature differential between flow and return should only be about 11°C and it could damage the boiler if this were greatly exceeded on setting 1.

Tony
 
Thanks Tony.

I'm still not quite sure what this DHW is actually pumping :confused: It doesn't seem to make any difference to my DHW when I turn the pump down from 3 to 1. It still flows out fast and it's still very hot.

...but if 1 still gives enough heat then thats OK.

I'm assuming it's OK, all my rads are too hot to touch when the systems on and has warmed up nicely:)

FYI I have a new Firebird condensing boiler 20kw
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top