WB 30SI v 30CDi Combi

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I've read through the litrature & can't really work out whether a 30CDi is worth the extra £80 or so over the Si.
If someone can explain this to me I would really apprechiate it.
 
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Off the top of my head, without looking in my tech and spec's

Quieter modulating pump on the cdi, less system noise due to reduced water velocity as trv's close down.

Quieter operating noise due to noise insulation on the wrap around panel.

Personal opinion that the boiler is of a far better build quality.

As well as a few other's that i cant think of, to early to start thinking.
 
get the cdi

with frost protection

AND with digital display you can see what temperature you are setting hot water at tap too.. should be 47


ideally so you cant scold you or the kids, cant waste gas by having it hotter than you need........... no guessing
 
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The CDi is a slightly larger physical size... Different/ better heat exchanger... Expansion vessel to the side of the boiler so easier to replace.. Easier diagnostics..

I have a 30Si and it is a good boiler... The 30CDi is a better boiler though
 
Si is inferior UK only model.

Cdi is based on German design heat exchanger.
 
Not many people realise the 30Si will only put out 24kw's on the ch and 30kw's for the hw. The 30 cdi is 30kw for both ch and hw.
 
Not many people realise the 30Si will only put out 24kw's on the ch and 30kw's for the hw. The 30 cdi is 30kw for both ch and hw.

Might only be me,you, worcester boffins and a shed load of RGI's thar know that then :LOL:
 
Si is inferior UK only model.

Cdi is based on German design heat exchanger.

You British are pretty unique in viewing anything British is inferior to anything German and it is something that is hard to understand. The Brits still have some of the best engineers in the world. The Si is a fine little boiler and will fit where a CDI doesn't... The CDi is a little better and therefore costs a little more. If everything was left to the Germans we would have the R30HE, a very good boiler but very inefficient in its use of space.
 
I have a British Kidd boiler in my own home. It cost me nearly £2.8K for the boiler alone, and I'm in the trade. So I'm not anti British.

If you are looking at mass producers in the boiler market it is unfortunate to say there are very few UK manufacturers out there achieving World class. Worcester is probably one of the few, but still have to make a cheapo range to satisfy the mean UK householder.
 
Thanks for helping me with this.

WB certainly seem to come highly recommended, but I have to say their website / comparison tools are pretty poor compared to other manufacturer websites I have looked at.

Anyway - back to the topic in hand.

It all depends how many radiators you have, bathrooms and the size of boiler to fit a certain size in a cupboard
I have 11 radiators in all (2 of them are fairly small).

The boiler will be going in the garage, so the extra size of the CDi is not a problem, given that it isn't that much bigger.

get the cdi
with frost protection
AND with digital display you can see what temperature you are setting hot water at tap too.. should be 47
ideally so you cant scold you or the kids, cant waste gas by having it hotter than you need........... no guessing
I thought the 30 Si had frost protection. As its going in the garage I certainly want that feature. Can you show me where this is documented please...
Digital display of temperature sounds pretty useful too, so that certainly adds to the pro's of the CDi.

Not many people realise the 30Si will only put out 24kw's on the ch and 30kw's for the hw. The 30 cdi is 30kw for both ch and hw.
Thanks for pointing that out.
Will I see much difference with only 11 radiators? I assume the rad's will heat up quicker with the 30kw?
I think people don't realise this as the WB website / literature doesn't exactly spell this out... This is certainly an area WB could improve on anyway.

The Si is a fine little boiler and will fit where a CDI doesn't... The CDi is a little better and therefore costs a little more. If everything was left to the Germans we would have the R30HE, a very good boiler but very inefficient in its use of space.
Sounds to me like the Si has been made to accommodate the shrinking UK house ;)
 
So looking some more at the specs these are some differences which I would like to understand...

30Cdi:
Condensing in DHW mode. What advantage if any does this give me?

30Si:Built-in boiler bypass
30Cdi:No bypass required
Is there a difference between the above??
 
Any boiler going into an unheated space requires an additional external frost stat to protect the pipework at the boiler because the boiler's frost stat will only protect the boiler then turn off the boiler once boiler internal temp has been reached.

However you should ,as has been pointed out to me here before,also fit a pipe stat to the exposed pipework in order to control the internal temp of the house.

Both items will cost about £40 plus labour for the additional wiring etc.

No doubt your installers will tell you the above is rubbish,believe me,it isn't.
 
So looking some more at the specs these are some differences which I would like to understand...

30Cdi:
Condensing in DHW mode. What advantage if any does this give me?

Thought that would be obvious .Cheaper hot water production. So if you use a lot of hot water then the savings will be much greater also get yourself the DT10 RF stat which enables you to time the Eco function of the CDI rather than just having it either on or off,best of both worlds really.

CDI is a brilliant boiler ,only one I would fit to my own house now.

If you go for a WB AI (approved installer)you will have either three or five years warranty as standard with either of these boilers and the AI can purchase four years WB servicing for you at a nominal cost. Two additional years' warranty and the four years WB servicing cost the WB AI £215 +Vat.
 

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