Doctor Drivel wrote:

"Nightjar "cpb"@" "insertmysurnamehere wrote in message
...
Doctor Drivel wrote:

"Nightjar "cpb"@" "insertmysurnamehere wrote in message
...
...
Reliability is more about make than type, although a system
(regular-type) boiler is less complex than a combination boiler.

Not much at all. A combi is system boiler with a 3-way valve and a
plate heat exchanger for DHW. 90% is the same.

That is still more complex than a system boiler.

Not much.

The other advantage of a system boiler is that the hot water is
stored in a tank, which can have a backup immersion heater and that
gives you belts and braces cover.

An in-line instant electric heater can be fitted in the combi outlet.
A small box say under the sink.

They are fairly useless if you want to fill a bath though.

It is for backup and will do a shower.

I don't have a shower or a shower attachment.


If you want full backup have two boilers and one being electric and a
backup genny as well. Where do you want to stop?

An immersion heater in the hot water tank will do me. I said backup, not
paranoia.


Both types are available as modern condensing boilers.

My personal preference is for a Vaillant system boiler and mains
pressure hot water tank, both of which are sitting in my side porch
awaiting installation.

A poor choice as the unvented cylinder is a potential bomb.

Worse than a couple of air receivers working at 11 bar?

Uh?

It would seem to be a simple enough question. Is an unvented cylinder at
mains pressure a greater danger than two similarly sized air receivers
working at 11 bar? I've had those around for over 20 years without being
worried about them blowing up.


Unvented cylinders need an annual service costing £60-£100 a year.

Wow, a whole pound or two a week.

That is £100 in 10 years. £2000 in 20 years. Not economical at all. Sell
it now!!!!

Interesting maths. £100 in 10 years = £2000 in 20 years. In any case, if
that really worried me, I will be saving more than £1000 a year in road
fuel when I downsize to a 2.5 litre diesel Mercedes E Class in September.

The best, if you have the mains pressure and flow is a high flowrate
combi.

Been there, tried it, did not like it.

Which one?

Long since forgotten.

What kW?

They were rated in BTU in those days and, like the make, I have long
since forgotten.

You never tried an ATAG

I can't say I have ever rated the Dutch as world leaders in engineering.

Floor mounted like the Worcester-Bosch 550 or wall mounted like the
ATAG 51kW. The ATAG is quality. It works out cheaper to fit and
install and saves a hell of a lot of space and no bomb in the house
or need annual service expenses.

You don't have your gas boiler serviced every year, but worry about
the dangers from an unvented cylinder?

I do not have my boiler serviced?

You claim no annual service expenses and I don't know anyone who
services boilers for free.

It is mandatory to have the unvented
cylinder serviced.

It is mandatory to have the air receivers serviced. So what?

Colin Bignell