Replacement CH boiler

My new house comes complete with a Baxi Barcelona CH boiler which repeatedly locks out. following speaking to a plumber friend of mine and reading up on numerous horror stories on the web, it seems that I may be wise to replace the whole thing.

The house is a large, 4 bed, detached Victorian house with an attic conversion. Currently there is a family bathroom plus a small bathroom in the attic conversion and a total of 20 radiators. Once we complete building work I expect to have an en-suite with shower, a guest bathroom with bath and shower, plus a bathroom in the attic conversion which will either have a shower or bath with shower over. I have 2 growing daughters who will soon be competing for hot water first thing in the morning and it may well be realistic for 2 showers to be running simultaneously.

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...

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 (though this declines to 11l once the 'heat bank' is exhausted). Am I 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 offering me mates rates utilising his trade discount to get the 40CDi for circa 940+VAT...which seems better than anything google has found.

Any alternative boiler suggestions ?

TIA,

Craig

Reply to
CraigB
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Does your plumber friend need to buy lots of christmas presents? ;-)

If you've got a pressurised HW system, that you plan to keep, then I don't see why you're considering combi boilers.

Reply to
adder1969

Well I'd be making efforts to investigate the reason for the lockouts. If you really want a new boiler which may or may not have its own set of problems fine, but the heating season may not be the best time to change. You'll regret losing mains pressure stored hot water if that is what your, I assume plumber is suggesting. Perhaps he is suggesting retaining the Megaflo and just connecting a single DHW outlet, best the closest to the boiler. That could be a good arrangement.

The purchase price would be a good price but is your friend installing FOC? Do you have a modern control system?

Too many variables to make much sense of your question. The suggested boiler would eat the heat demand more economically but that's the simple part.

Jim A

Reply to
Jim Alexander

Mains pressure hot water cylinder basically.

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.

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.

You need to measure the flow rate you can get from the cold main however, as this is going to limit what you can expect to achive[1]. How much flow you need will also depend on your expectations regarding shower performance (4 lpm would equate to a crappy electric shower, 7 -

15 lpm would be a average mixer shower, anything up to 30 lpm if you want showers with drencher heads and body jets etc). [1] If you run out of flow rate capability, then you would have a few options ranging from upgrading your cold main, installing an accumulator to provide a buffer of mains water, or adding a conventional storage system for filling baths and/or a pump for the showers etc.
Reply to
John Rumm

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!)

Reply to
CraigB

The first thing to do would be to work out if you have a problem. If not it may be better to not fix it until you do have one.

Try the boiler choice FAQ

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the sealed system one:

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Reply to
John Rumm

On 11 Dec 2006 09:59:40 -0800 someone who may be "CraigB" wrote this:-

It is one way to get mains pressure hot water.

If you add more outlets then you may find that the cylinder is now too small to cope with the usage pattern. If you don't want to live with this then there are a number of options for changing the system:

1) a larger cylinder.

2) two or more cylinders (possibly smaller than the current one), situated to feed local rooms. This will also reduce wasted water and heat due to long dead-legs.

3) a thermal store.

I would only recommend a combination boiler if the hot water output was feeding a local sink and/or basin (for example a kitchen sink and cloakroom basin). These are only filled for relatively short periods, so the boiler will not be diverted from recharging the rest of the system for long periods of time.

Reply to
David Hansen

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