On Fri, 10 Sep 2004 16:56:07 +0000 (UTC), (Fred)
wrote:

"Christian McArdle" wrote:

Ah, right. I couldn't do without my baths, though! I lived with a
shower for 12 years (i.e. no bath) and the joy of a relaxing, piping
hot bath, especially on a cold winter's morning, is irreplaceable.

Don't get me wrong. They will still fill a bath. It's just that if you have
one daily, you may find the wait too long, unless you develop a habit, such
as getting breakfast whilst it is filling.

Christian.

But this is just not true for most decent combis. Here, I live in a
tank system house. The hot water is a hot dribble really, the pump is
only used for the shower and sounds as if I have a Moto Guzzi in the
house.

Then you didn't have the tank system fitted properly because it's
easily possible to have a substantial flow.

If your pump makes a lot of noise, you either bought a cheap one or it
wasn't fitted properly.



While I have seen combis in various locations in the UK where
the hot water at mains pressure. This results in a high flow at least
in areas suitable for combis, not to true for other areas where combis
should not be installed - ask your plumber. I usually take a bath
after doing the dishes in the evening, my bloody tank is not big
enough and with the heating on, it takes forever and a bit to fill the
tank. Not an issue with the combi, where hot water is on demand.

No guys, where combis can be done (depending on mains pressure), they
usually beat a comparable tank system flat out.

That is demonstrably nonsense. There is no physical way that even
quite a large combi system can deliver hot water at a greater rate
than a tank storage system provided that the pipework is adequate on
the storage system.

Well, to be honest, I
have never seen a new tank system, but plenty of new combi systems
here. And the thing with the cold water tanks in the loft dribbling
through your house makes you feel as if your buddy has a chronic
prostate problem ;-) Oh and for hygienic apostles amongst us all, take
a look in the cold water tank, then think about the hot water tank,
where hot water stays for days. And then count the bacteria.

If the hot water cylinder stores the water at 60 degrees there will
not be a bacteria problem.


A combi
basically serves up drinking water (well, I would still not use it for
tea though ;-))

Right. Final issue: water temperature. The combi's performance depends
on the distance between boiler and bath. The closer the hotter the
water. The tank has the same issue (hence its usual location in the
bathroom) but, BUT, a mildly old tank system will loose heat = the hot
water is not of the same temperature. Kind of sucks when you keep your
hot water at a low temperature only to find out that your bath is
lukewarm because the water was sitting in the tank for a day or so.

This is complete nonsense.

The rate of water production from a combi is *highly* dependent on the
incoming water temperature and the flow rate.
This is not the case where the DHW is stored.

Neither will give any significant temperature drop between the point
of heating and point of delivery in a normal house.



I know it comes down to personal preference, but don't sell combis as
having problems to fill a bath. With any decent combi that just is not
the issue.

A combi is suitable for a flat or very small house, or where the
occupants have modest requirements for hot water delivery.

For a 3-4 bedroom house wiht multiple occupants, the performance
becomes increasingly inferior to storage. Storage can be by directly
storing the DHW in a cylinder, or via a heatbank, but is the only way
to get good results where multiple bathrooms are in use.




Fred

..andy

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