Which boiler is better?

Hi there,

First post. I am currently in the process of deciding which boiler to have installed in my flat ( 4 bedrooms, 1 bathroom and 1 en-suite). The main bathroom has a bath and a thermostatic mixer bar. I haven't decided whether to install a thermostatic mixer or an electric shower in the en-suite yet. There are 9 radiators in the property with two of them being monstrous 2 metre long by 600 high double convectors.

The supply gas pipe from the meter to the current boiler is in 22mm pipe, the length of run is approximately 24 metres.

The cold water main is old copper pipe sizing of 21mm. Pressure was measured at just under 4 Bar with a flow rate just over 21 litres per minute. This was measured at the kitchen sink mixer tap.

The run from the boiler to the bathroom is also approximately 25 metres.

I don't have the space for an indirect un-vented cylinder or the mains flow rate required for it as suggested on this forum. So I am limited to large combi's.

My first two options were the Worcester Bosch 42cdi and the Vaillant ecoTEC plus 937. After spending some time reading through the forum, would the Veissman Vitodens 222-F be suitable for my installation.

I am trying to get the most efficient system I can get that can adequately supply the hot water requirements for four adults and two young boys.

Thanks.

Just over 12 months ago i had fitted in my 4 bedroomed house,a new Worcester Bosch Greenstar gas 37cdi combination boiler I am more than pleased with the boiler which serves 11 radiators fitted with TRV`s in the main rooms,wet under floor heating in a large conservatory and ample hot water to to 2 showers and a bath. I am somewhat suprised that my gas usage has gone down a lot over the past year, even though the new boiler is 3 times bigger/more output compared to my old clapped out boiler. Hope this helps in helping you decide wich boiler to go for.

GoingNorth said:

Hi there,

I don't have the space for an indirect un-vented cylinder or the mains flow rate required for it as suggested on this forum. So I am limited to large combi's.

Thanks.

Click to expand...

Dont you realise that the same flow rate is required for a combi as an unvented?

Its the dynamic flow rate thats relevant not to open pipe flow rate.

I think that you will have to accept that its not going to be possible to use both bath and shower together within the limits you are imposing on space.

Have you seen the size of the Vitodens 222 ?

Tony