In article ,
Christian McArdle wrote:
I see absolutely no advantages to open systems than these marginal ones:

1. Your boiler might require it.
2. You already have one and don't want to spend 50 quid upgrading.

Only 50 quid? And how about the reliability of pressure vessels?

3. Certain heat bank applications with common circulating water.

The advantages list goes on and on. Header tank systems rarely work well
or predictably, which is why sealed operation is now the norm.

I reckon you're much exaggerating the problems with header tanks. And I'd
say sealed systems are popular for the same reasons as combis - they are
easier to install so make a larger profit for the plumber.

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*Sorry, I don't date outside my species.

Dave Plowman London SW 12
RIP Acorn