Hi all

I'm baffled (not hard, I know !) My daughter has an Alpha CB24X -

http://www.danthegas.com/boilers/Alp...e%20Manual.pdf

combi boiler in her house, which is a retrofit in place of an original
indirect storage system. It was done before she bought the house. Unit is
wall mounted in the kitchen and has two large-bore pipes heading up through
the ceiling (CH flow and rtn ??) and four 15mm pipes heading down ( gas in,
cold in, overflow and hot water out it would seem from the manual).

House is typical smallish semi from about 15 years ago, and the bathroom is
just above and to one side of the kitchen, so pipe runs to upstairs not
long - probably 5m max.

So she calls me tonight and says that her shower is only warm (it's an
in-wall thermo mixer fed from the hold and cold feeds to the bath taps) and
that she tried a bath the other night, and that too was only warm. I asked
her where she had got the hot water thermostat set on the boiler, and she
said right up at No9, but that she used to only have it at No5, and the
shower was fine. Neither she nor her husband normally take baths, and the
shower was in when they bought the house, and has been fine up until now. A
few months back, we fitted a new bath with new taps, and also a new basin
and taps, but all the existing pipework was left intact, the only change
being that the bath and basin tap feeds were just cut a few inches below the
original taps, and flexi tap connector to push fits installed to make the
connections to the new taps. No service valves were fitted in these feeds,
and everything has worked fine since the job was done, until this problem
developed.

I then asked her how the kitchen water was, and she said that it was too hot
to hold your hand in. Initially, I thought that she might be looking at an
issue with the temperature of the incoming water, but the fact that the
downstairs water was very hot seemed to knock that one on the head.

I went over there to have a look, and she is dead right. The downstairs
water is blisteringly hot, the bathroom water - shower, bath tap and basin
tap - is best described as feebly warm. Given that there only appears to be
one hot water outlet from the boiler, which presumably splits somewhere
under the kitchen worktop into downstairs and upstairs feeds, what on earth
could be causing this odd symptom ?

Any suggestions gratefully received ... d:-\

Puzzled Arfa

On Wed, 04 Feb 2009 09:44:53 +0000, Arfa Daily wrote:

That was my first thought too John, but I turned both the basin and bath
taps down to perhaps a quarter of fully on, and left them running, in turn,
for perhaps 2 minutes each. There did seem to be a slight improvement in
temp, but not as much as I might have expected. Just to make sure that I've
got the operating principle right. These combi boilers heat the water
'on-the-fly', right ? A heat exchanger with cold water in and a bloody great
fan-blown flame up its chuff to give hot water out the other end, yes ? Some
already-hot water 'stolen' from the CH via a diverter valve and a secondary
heat exchanger comes into it somewhere ? So basically the gas equivalent of
an electric 'on-demand' shower ?

Yes. If you set the bath tap for the same flow rate (time to fill a
given-sized container) as the kitchen tap, is the water the same
temperature?

If not, what's happening? Is the bath tap a mixer with one knob that's
somehow not allowing full hot through (or as dennis suggested,
a thermostatic mixer)?

If you're sure the bath tap is only passing water from the DHW supply (i.e.
from the boiler) then what's happening at the boiler? Can you see the
flames? Is it burning less fiercely when supplying the bath tap than the
kit sink one at the same flow rates? (You can tell by measuring how fast
the meter's clocking up gas usage.)

If the boiler's running at a lower gas rate for the bath tap than the sink
then I'm stumped for now, but at least you know it's something telling the
boiler not to work so hard in this case. Maybe this season correction
valve gizmo you refer to? (I've not come across thos before, but the only
place I've seen Alphas is in a scrap yard :-))


--
John Stumbles -- http://yaph.co.uk

I forgot to take my amnesia medecine again

"Arfa Daily" wrote in message
...
Hi all

I'm baffled (not hard, I know !) My daughter has an Alpha CB24X -

http://www.danthegas.com/boilers/Alp...e%20Manual.pdf

combi boiler in her house, which is a retrofit in place of an original
indirect storage system. It was done before she bought the house. Unit is
wall mounted in the kitchen and has two large-bore pipes heading up
through the ceiling (CH flow and rtn ??) and four 15mm pipes heading down
( gas in, cold in, overflow and hot water out it would seem from the
manual).

House is typical smallish semi from about 15 years ago, and the bathroom
is just above and to one side of the kitchen, so pipe runs to upstairs not
long - probably 5m max.

So she calls me tonight and says that her shower is only warm (it's an
in-wall thermo mixer fed from the hold and cold feeds to the bath taps)
and
Any suggestions gratefully received ... d:-\

Puzzled Arfa

I reckon it is the divertor valve that needs replacing.

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