On 16 Apr 2004 05:22:43 -0700, (Dave Phillips)
wrote:

FOlks

Quick boiler question...

I currently have a Saunier Duval combi boiler installed in my house.
The install dates from 1987, i.e. before I lived there. It has been
running fine, although possibly not terribly efficiently of late (my
perception).

At a recent routine service, the engineer (the same company as I've
used for some years) says that the boiler will need some fairly major
parts replacing: heat exchanger, pump etc, which will cost a few
hundred quid. I was expecting this. He then looks at the pipework
leading in and out of the boiler, and tells me that it is actually the
wrong size (15 mil instead of a larger size- maybe 22mil?) and points
to the various step-down pipe adaptors fitted there to enable just
that fact. I actually knew about this already, since another engineer
from the same company had told me the same thing some years ago, so I
am not too surprised to hear it again.

My question is this. Is the wrong size pipework a major problem;
should I have the current boiler repaired or should I have it
replaced,

At that age, it is nearing the end of its useful life. I wouldn't
spend several hundred quid on it.

In most domestic installations, apart from ion large properties, 22mm
at the boiler flow and return is normal and adequate. Below this,
the flow rate through the pipes becomes inhibited and it's difficult
to transfer the heat. To some extent the pump deals with this, but
to mode the same volume of water, it has to flow faster and more
noisily. Beyond a certain point it's not really possible to go
further. In short, the pipes from the boiler and forming the main
trunk to the radiators should be in 22mm up to a point where enough
branches to radiators are done to bring the flow requirement to a
sensible level.




and in the latter case, would I have to have a condensing
boiler fitted rather than another combi?

This isn't the decision.

You can have boilers without combi function that heat radiators and a
cylinder or you can have a combi. Separate to that, you can have
condensing or not in both types (i.e. 4 main permutations) Actually
there are more, but this is the essence.




I believe there are new
regulations about boiler efficiency coming into force next Spring?

It has been mooted that the minimum SEDBUK efficiency will be raised
to 86%. This is not achievable with the typical 78-80% conventional
boiler of current manufacture. Whether that happens before next
Spring is not completely clear, but it is the aim.

It is beneficial to get a condensing boiler anyway and yes you can get
a condensing combi.




One more thing. Bear in mind I will probably move house next year.

You may prefer to get a cheap non-condensing combi in that case.



tia
Dave P

..andy

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