Boiler Choice

15 Sep 2006
Reaction score
United Kingdom
Sorry, I know this is a DIY forum, but I figured you guys would be the best people to ask.

My wife is having a grant for central heating. The plumbers say that the standard boiler is a Worcester Bosch Greenstar 28i junior. My wife has a bath every night, and we wondered whether it would be worth upgrading to the Greenstar 30CDi, it has a slightly better flow rate, which we thought would fill the bath quicker (mind you, anything would be better than our old Potterton Puma 80e and its 20 minute fill time).

Is the 30CDi worth the extra, or is there not much in it?


Sponsored Links
The 28i Junior has a DHW flow rate of around 11.4 (lpm) the 30CDi has a flow rate of around 12.7. Not much of a gain, but cetainly would nitice the difference and fill that bath quicker.

I guess it's up to you to justify the value of the wife being able to run a bath quicker... Does it mean you get your tea any quicker?

You could, of course, go for the 37CDi or the 42CDi, with 15.1 and 17.2 respectively, but the price does start getting a little scary then.

Then of course is the matter of your incoming mains flow rate. If that is low, not much point going for a monster of a boiler.

Your bath should hold around 150L so say worst case you will be filling entirely with hot water to 140L... thsi will take 12.3 minutes with the 28I Junior, or 11 minutes with the 30CDi.

Hope that helps, nice long answer as stuck indoors waiting on a delivery!!!

Good luck
Your Puma is 24 kW and if that takes 20 minutes then the 32 kW will take 25% less or 15 minutes.

Maybee you have a very large bath? Or your Puma may be operating at less than full power.

Combis are best for showers! In which case a 24 kW is adequate but 28 kW better.

If you must have baths then a 35kW would be better or the best would be a storage combi as they have a small tank of hot water which is dumped into the bath within 4-5 minutes.

If any of my customers state they have regular baths as opposed to showers I always recommend a 37Kw combi.
Sponsored Links
I'd fit a 28 a tell the customers to share the bath.

Marriage harmony then commences!

tis all very well saying all this but only a competent person on site knows what is possible in you case. There are jobs when a 24kw combi is all that is possible, there are places where only an 11kw regular boiler is possible.

Just talking about bigger and better combies is not the whole story.
Can I just say Soft, respect to you for standing up to those biggoted sparkies. I ducked behind the parapet. You are a real tenacious feller.
Coming from you Paul, that's a comment I value hugely.
well respect m8.

There seems to be an inbuilt hatred of plumbers in some sparkies, and a huge amount of arrogance about their interpretation of regs.

The napit forum is so bad I've given up.

You can't have a sensible intelligent conversation they just imediately start calling you a wind up merchant. I never realised there were so many closed minds.
I haven't looked on napit - there are only so many hours in the day. ;)

I find the sparkies on DIYnot to be a very patient and civilised bunch. They put the plumbers on here to shame.

BTW, hinting back to another topic a few weeks ago, I still haven't got myself a copy of the 16th - I keep stalling because I'm perpetually amazed that something that's held in such regard by so many people isn't available, online and for free, for everyone to read and understand. I know I'm swimming against the tide and I'll have to buy it eventually, but it smacks of a tired old tradition that no longer serves anybody except the publishing and printing companies involved. Ho hum.
maybe someone might copy onto cd for you when he isn't running around like a lunatic.

It's very boaring though and pretty useless as all it does is make a statement open to interpretation. The interpretation is in the guidance notes the osite guide the electricians guide to the building regs and the particluar certifying body you go with.

It's actually lead to a huge variation in practices. But the big problem is all he guys who call themselves sparkies but have been doing a cr ap job for the last 50 ears, not niceic registered as it wasn't obligatory until part p to be a member of a class of persons as in corgi.

They got one thing right with part p, made competition among providers. corgi monopoly is a notable situation to avoid.
I'm sure such kind people are few and far between. ;)

I have the OSG, and I daresay that I'd be as bored as anyone else by the WRs, but a lot of discussion here is based on what they actually say, and I find myself at a distinct disadvantage.

Good observation about avoiding repetition of the CORGI mistake.
The lack of resolve by government or their advisors to smash the monopoly is now shown up in floodlights in contrast to all the other work activities requiring a membership.

The public can decide if the duplicity demonstates corruption, ignorance or apathy.
I'm firmly in the "it's corruption" camp, and am wholly displeased by the use of the "CORGI" brand to create a new profit-making company that's selling 'professional' services on the back of a safety remit. The utter, utter, utter b*stards.

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