DIYbanter - View Single Post - Combi or not combi

Terry Casey

In article , says...

The first question is do you actually *need* a new boiler? What's wrong
with the existing system? There's no point in replacing it just because
it's "old" if it works ok and if spares are available. [My boiler is far
older than that - and still going strong - although I have updated the
controls.]

We've been discussing this and, whilst we haven't come to a decision yet, we
are thinking of just having the system flushed at the moment plus changing
one or two TRVs to see what the effect is.

We have been told that there is water being pumped into the header tank and
there is certainly a dripping noise when it is very quiet. My wife finds this
disturbing and can hear it if she has an early night before the heating turns
off and when it comes on again in the morning. If the system is flushed I'm
hoping the improved flow will get rid of this.

Another thing we've noticed is the number of times the boiler turns on for
a short period, then shuts down again when the heating is on which, again,
I'm assuming is caused by the restricted flow.

If you are convinced that you *do* need a new boiler, the choice between
conventional and combi depends on many factors.

Firstly, do you bath or shower? Even a good combi will take a long time
to fill a bath with hot water compared with a stored hot water system.

Bath in the bathroom and en suite electric shower

Are you desperate to get rid rid of your hot water cylinder in order to
redeploy the space for some other purpose?

There is very limited easily accessible storage room and my wife would love
to regain the space that the cylinder takes up in the airing cupboard!

Have you got decent pressure and flow from your cold water mains. I
think the figure often quoted is that the mains needs to be able to
deliver at least 14 litres per minute at the point of entry - often the
kitchen tap.

I will check this when we return next month

Is your gas pipework up to the job. A combi will consume gas at a very
high rate when heating the hot water (as opposed to the radiators) so
the internal gas pipework may need upgrading.

Improving gas flow included in combi quote

--

Terry

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