"Adam" wrote in message
om...
First of all, thanks Bob for all the excellent information. I did
some investigating last night, and...

snipped

There are just three pipes leading to the boiler - I assume these are
the inflow, outflow and gas.

There appear to be three pipes leading to the cylinder, although I
presume there's one more I can't see - I assume these are the mains
input, hot water output and boiler system inflow/outflow.

The pipes adjacent to the hot water cylinder appear to originate from
the boiler (at least, two disappear under the floor, roughly towards
the boiler, and were warm when I was working last night. One (I
assume boiler outflow) appears to feed the cylinder via one motorised
valve, has a pipe leading off (I assume) to the bypass and feeds what
appears to be the rest of the heating system via the other valve; it
is also connected to the mains water via a flexible hose. The other
(I assume the boiler inflow) appears to feed the cylinder and the two
heating pipes. Of course, they also appear to be connected in random
ways to each other, but the heating works, so I'll ignore that!

There were two hand taps in the cupboard: one is on what I assume is
the boiler inflow pipe, just next to where it exits the hot water
cylinder; the other was on the boiler outflow pipe, above the joint
that leads to the T-joint to which both motor valves are attached.
Opening each of these about a half turn appears to have given us hot
water this morning despite the 'hot water' switch (electrical
immersion heater) being turned off.

So I assume the electric immersion heater is a backup system to the
boiler, which now *appears* to be working.

-8- snip details of replacing immersion heater and/or hot water
cylinder -8-

I hope replacement won't be necessary, at least for the moment. Will
the kettling cause lots of damage, or is it mostly just an auditory
annoyance?

It sounds as though you have now analysed the system, at least. A few
comments:

Your presumption on the pipes to the cylinder is probably correct - it is
likely the cold feed to the cylinder (from a header tank in the loft/on top
of the cylinder/somewhere else above it) is round the back somewhere. The
pipe that comes out the top of the cylinder is the DHW (domestic hot water)
take off, where the water for the hot taps comes out. The heating pipes
from/to the boiler normally come in and out the side, one above the other
(inside they are connected by a copper coiled pipe which keeps the DHW and
the boiler water seperate but allows heat exchange).

There should be a thermostat on the cylinder between, vertically speaking,
the boiler pipes. This will open the motorised valve and request heat from
the boiler (if the water switch is ON) when the water temperature drops.
There must be a heating/water control panel somewhere (behind a cover in the
boiler or on a wall somewhere).

The big question is "why was the water circuit valved off?". I fear I can't
imagine anyone doing this unless there was a problem! One likely problem (if
there is one) is a leak between the heating coil in the cylinder and the
DHW. If you run the system as it is intended, and there is a leak,
eventually the DHW cold header tank will overflow (the pump pressure forces
water from the boiler circuit into the DHW and "backfills" it). An
unscrupulous seller might have just valved off the tank and switched to
electric heating and not said anything. OTOH they may just have been stupid
and not realised it was valved off! I hope it's the latter.

The kettling will just be an auditory annoyance but it may still be worth
checking the immersion heater thermostat.

You are, at least, at the stage where you can experiment and found out how
the system operates and if necessary repair it rather than be faced with a
non-existent system.

Good luck.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)