Choosing a WB Combi

[robmorgan]

Hi all,

I'm deciding which WB combi to go for, from the 28si up to the 37CDI.

4 bed house, 1 bathroom with shower, possibility of loft extension including shower room at some point.

28si would do for now I'm sure, but looks like the 27CDI or 30CDI would be worth a bit extra for the HW temp control.

Can the 27CDI and/or 30CDI handle two showers running at the same time or should I consider spending a few hundred more on the 37CDI to be on the safe side?

Thanks for your help,

Rob

 

[bengasman]

The CDI is far better than the SI, not only due to the extra control option, it is all together a better design.
The 37 kW model will happily run 2 showers at the same time, unless you are one of the people that wants a shower to chuck water out by the bucket.

I have installed a number of 37 CDI's, as well as it's predecessors which were 35 kW, and they all work fine with 2 showers.

You do need an adequate incoming mains of course, but that is not a boiler issue.

You can get "high efficiency" shower heads these days, and 2 of those fed by decent thermostatic mixer might just about work on a 30 CDI, but for the 100 quid difference, I wouldn't risk it.

 

[kevindgas]

the 28Kw version will just about supply 2 showers but the 37Kw would be better in the long term.
also worth looking at the Vaillant Ecotec 837. either would be good.

 

[robmorgan]

Thanks for the advice. 30CDI or 37CDI is looking like the way to go.

Please can you explain how the design of the CDI is better than the SI?

 

[bengasman]

Bit of a lengthy and technical story to type out, but you can download the technical manuals from the website, and compare the contents of both models.