"John Stumbles" wrote in message
news
On Sat, 08 Apr 2006 14:53:31 +0100, John Rumm wrote:

JavaEnquirer wrote:

If the primary side fo this gets cloged with rust or other debis then it
is often going to need replacement to restore decent hot water
performance.

Have you heard of this actually happening on a system that's been flushed
(chemically, not power-flushed) and treated with inhibitor in accordance
with the boiler manufacturer's instructions & benchmark requirements?


Well a simple strainer on the return will go a long way to catch any
rust etc before it gets to the boiler and is only a five quid part.
Nothing stopping you buying one and asking the plumber to fit it (pref
with a couple of full bore valves either side to make servicing easy).

The valves are a must. The strainer will block up with a minute amount of
crud and stop effective circulation in the system. (You'll know because
the boiler will short cycle.)

Could this be down to the actual boiler? Do some have in-built filters?

AFAIK only the Alphas, which have a cyclonic trap to encourage sediment to
precipitate out into a chamber (which can presumably be cleaned out
periodically).


I'm going for a Worcester Combi Junior 28i.

Out of curiosity, why do so many people fit the Jnr model? Is it that
much cheaper? IIUC the Jnr models are very similar to the Si models
however they only run in condensing mode for CH, and not for HW. So you
are throwing away some of your potential energy efficency gains.

They're a lot lighter (advertised as being a one-man lift) so they're
attractive to installers working singlehanded. I wasn't aware of
(and I'm a bit surprised about) the difference you quote in DHW mode,
although I don't think that's a major issue: condensing boilers
are still more efficient than non-condensing ones even when they're not
condensing, and the amount of energy used providing DHW is
generally vastly less than for heating.

My brother fitted a strainer after I mentioned them to him, and he found
quite a lot of debris in it after he had run the combi for a week and
drained it down to refill with Fernox. Mostly it was solder splats, copper
shards and bits of cloth etc. Of course, he did not flush the pipes out
before turning on, so it was a lazy way of catching the debris.

Andy.