In , David W.E. Roberts
typed:
: Hi,
:
: just catching up on the NG after a few days away.
:
: Currently there seem to be several threads about problems providing
: hot water at a decent flow rate with combi boilers.
:
: Now I can see that with a good high water pressure and flow rate, and
: a limited number of outlets, the combi boiler allows you to install a
: domestic hot water system with a much reduced component count, saves
: space previously used by header tanks and hot water cylinders, and
: can give you a nice hot shower without needing a pump.
:
: However with low water pressure and/or a large number of outlets (and
: according to the TV shows a house is not a house without at least one
: en-suite in addition to the family bathroom) the combi starts to
: struggle.
:
: Fixes suggested include installing a header tank and pump for
: additional cold water pressure/flow and adding a hot water storage
: tank to provide enough hot water at peak times.
:
: Once you start down that route I must ask "Why was a combi fitted in
: the first place"?
:
: Seems to me that at the moment the automatic design for a new system
: is to use a combi boiler.
:
: Surely this is best for flats and small houses, and any reasonable
: sized house should be designed with hot and cold water storage
: because the peak demands cannot be supplied by heating water
: 'straight from the main'.
:
: Or am I missing something :-)
: [Hmm...cheaper option for the developer?]
:
: Cheers
: Dave R
:
: [Also noted comments about 'high output' combis which need so much
: gas that they need a larger gas pipe and can compromise pressure for
: other customers. In this situation a slower heating coupled with
: storage of hot water seems a more sensible option. Peak flow of gas
: and water must limit to the amount of hot water you can supply
: through an 'instant heater'. Then again, how about a pumped gas
: storage tank to supply extra gas at peak demand without compromising
: the main supply - design for a mini-gasometer anyone?
: Hmm...compressor fed from the mains to fill a high pressure tank with
: the outlet pressure reduced back down to mains gas pressure but
: through a large bore pipe?]

As a house owner with an old boiler, header tank and all the rest of it,
I'm terrified about changing the thing to a "combi". But all the
plumbers I talk to want to sell me one, & did notice that they only want
to sell a Combi. It does ratherm remind me of the endowment sales of the
1980's.

The problems asked about Combi's in this NG must be the highest thread
count here? It makes me wonder what the rest of the population who don't
post here suffer from with CH and Combi's? It's certainly enough to make
me never want one. They do seem to be easy fit/fat profit devices, but
I'm having a cynical day so do excuse me if I'm talking ****e.

I still don't ever want one of 'em.
--
ctc
Once, I couldn't spell 'engineer'.
Now I are one.