John Rumm wrote:

CraigB wrote:

The current Baxi system is coupled with a large (4/5ft tall ?) Heatrae
Sadia Megaflo cylinder and the hot water system is mains pressure. I
know next to nothing about how the Megaflo system works, which may
explain my next question...

Mains pressure hot water cylinder basically.

My friend has suggested (by phone) a Worcester-Bosch 40Cdi boiler,
which has lots of interesting stats. such as a 16l flow rate. Googling
has also found the Worcester-Bosch Highflow 440 with a 20l flow rate

The highflow is to all intents a purposes a large box containing the
components you already have. So probably not much point in changing to
that.

right in assuming that the Megaflo cylinder would mean that the 40Cdi
could meet my requirements as well as the 440 could ? He's also

Yup, probably better.

offering me mates rates utilising his trade discount to get the 40CDi
for circa 940+VAT...which seems better than anything google has found.

You don't really need a combi in this situation since your total flow
rate from both the cylinder and the combi would still be limited to
whatever your cold main can deliver. What is more, if you were drawing
water from the combi side, then boiler would not be able to reheat the
cylinder while you are doing it.

Hence a powerful boiler that can when required throw all its effort into
heating the cylinder would probably work better.


Thanks to all for answers to date. From what I can gather I've managed
to get my wires crossed and my mate (who is 200 miles distant and not
answering his mobile) has done nothing to simplify matters.

I want to retain the mains pressure hot water that I believe the
Megaflo system gives me and I'm considering replacing the Baxi as I
understand them to be troublesome and expensive to repair (based upon
mate's comments and googling). Additionally, as we're adding another
bathroom to the house I want to ensure I have sufficient capacity in
the system.

The current boiler is a condensing one I believe (as I've found a
condensate trap) and I was - it seems wrongly - assuming that the 40CDi
I was being recommended was a direct replacement suitable for extending
the capacity of the whole system. Happy to be advised otherwise.

I've been expecting a visit in person, but been let down on the last 2
weekends, so starting to think about calling in a local CORGI
registered CH specialist and want to get a better understanding of the
situation before I do so.

Looks like I need to do a bit more analysis/reading (never had to buy
or fix a CH system before!)