Worcester 30si or 30cdi?

[josiejump]

I've recently had a new Worcester condensing boiler installed with piping upgrade throughout the house and new rads. However, the wrong boiler was fitted in error (I'd gone for the Worcester 30cdi option but the fitters misread my email!). The error was only realised at the point they were ready to leave.

While I was assured that there was little difference in spec (and a £200 saving), I've looked at the Worcester website and am concerned that the si boiler range is suggested for 'apartments and small to medium properties' and the CH output of the 30si boiler is cited as only being 24kw. Is this sufficient for a fairly large 4-bed, 1 bath semi (11 rads)? The fitters say it is but that they are happy to replace if I want to, at the extra cost. I don't want to go to the hassle if what we have is good enough.

Can anyone advise please?

 

[Dan Robinson]

For heating it will be fine output wise.

But it is a totally different boiler to the CDi and if you can afford it I would pay the difference in the two boilers.

I assume they are only charging you the difference in cost for the boiler and not the labour?

 

[josiejump]

Yes they'll be charging the difference as per their original quote (they quoted for both types and actually advised the CDI - the error is wholly down to them misreading my reply!)

In what way is the CDI a completely different boiler though? They gave me the impression (once the error had been noted!) that the only difference was noise (which is not an issue) and the fact that the CDI doesn't allow control of hot water temperature (so actually a 'pro' in favour of the SI). The difference in CH kw output was something I saw on the Worcester website but other obvious differences in favour of the CDI are not clear (to me, at least!)

 

[Dan Robinson]

The CDi does let you control water temperature.

It also has a different heat engine entirely and a longer warranty.

The hydroblock is also slightly different IIRC, although it is still plastic and overpriced.

Trust me. If you must have a Worcester Bosch then you want the CDi. I do this stuff for a living .

 

[josiejump]

I've had a look at the operating manual for the CDi and you are right that you can control the water temperature but it says 'only in conjunction with the optional diverter valve'. I have no idea what that means! Is this something I need to request as 'extra'? The fitters told me that the CDi didn't have this function

Sorry to bombard you with questions - I just want to be fully informed before I drag them back in!

 

[Dan Robinson]

Are talking combi boiler or system boiler?

Do you have a hot water tank.

 

[josiejump]

Combi boiler

 

[Dan Robinson]

Then the CDi controls its hot water temperature in exactly the same way as the Si.

You were looking at the System boiler details.

 

[gigz]

Think you've been reading the wrong instructions

 

[josiejump]

Ah yes, so I have!

 

[josiejump]

Ok, so looking at the CORRECT instruction manual now I note that the 30CDi condensing combi stopped being manufactured last year! It's definitely the boiler the fitters quoted me as an installation option (and the one I originally chose!). I assume they must have some spare stock but will there be an issue with the warranty if this is a model WB no longer make? And idea what has replaced the 30CDi?

 

[Dan Robinson]

The CDi Compact; and I suspect there will be the old ones in stock and being sold for a few months yet.

Just make sure they register it for the long warranty.

The new version is nothing to write home about.

I haven't digested all of the literature on the Compact yet; but....

 

[josiejump]

Thanks. I'll take your advice and ask them to replace the boiler with the 30CDi model. Imagine I won't be popular but I guess it'll teach them to pay more attention when reading their emails! (I was quite clear and they admitted it was their mistake)

 

[Dan Robinson]

I was wondering how a mistake like that can be made.

The cynic in me says they were trying it on and you rumbled them.

 

[boilerdoktor]

the cdi has become the cdi classic, only diff really is no transformer, so it is still very much in production.

the cdi compact is a new one which is smaller and very different to the classic

both excellent boilers imo and as dan says a bit better than the i and si