"John Stumbles" wrote in message
...
On Mon, 24 Dec 2007 08:27:32 -0800, Onetap wrote:

The Baxi & the Potterton are made by the same company.
...
In fact, the circular stainless steel
heat exchanger in all the above
boiler looks very similar. I think it
may be made by Giannoni, or made
under licence from them.

There was a post-mortem of one of these on Gas News earlier this year,
which criticised some aspects of its design such as the
potential for a vertically mounted coil of tube to accumulate sediment at
the bottom of the turns, and the impossibility of flushing out a blockage
in one passageway plumbed in parallel with others:

http://www.gas-news.co.uk/archive/st...mment/1006.htm

These Giannoni heat exchangers are plentiful and are in millions of boilers.
Even Heatline, BIASI and Ravenheat have models using this heat exchanger.
They work OK indeed and have been around for quite a while. They are a
horizontal coil of stainless steel with the burner horizontal too. I prefer
the Keston vertically coiled heat exchangers with the burner on the top and
the flue outlet at the bottom. The condensate washes down the heat
exchanger cleaning it as it burns. The Keston Qudos is now a highly cost
effective well designed boiler offering high functionality too. This Qudos
boiler must be assessed when buying a boiler. Reliability is not yet proven
though, although most parts are taken from reliable Keston models, so should
be fine

I personally like the Atmos heat exchangers. It is whole of the boilers
back panel. The height and width of the boiler. This design uses all space
available and makes for a smaller boiler too. They are also very well made
of thick gauge copper too. The combi version just has a coil of copper tube
run through the heat exchanger and acts like a conventional multi-point
water heater when generating DHW. Have a look:

Look at the space inside the Atmos Intergas boiler for burner and pump.
Amazing!
http://www.atmos.uk.com/product_group.asp?section=000200130003

This shows the inside of the Atmos heat exchanger:
http://www.atmos.uk.com/core_files/productDoc(136).pdf