In an earlier contribution to this discussion,
Red wrote:
"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Nor sure how you managed to post your message at 10:43am - when it's
only 10:15 at the moment! Please check your computer time clock (not
that that has any bearing on your shower/heating problems!)
Sorry my post was so controversial. My clock is indeed correct. Im
writing this reply at 18:52 If it shows as earlier, i don't know why.
This message is timestamped at 19:58! Have a look at the International
settings on your PC (Start/Settings/Control Panel/Regional and Language
Options) and check that it knows that you are in the UK rather than in
France or somewhere).
With regard to these, you will need to tell us a bit more about your
setup before we can sensibly comment.
I'll do my best, but im afraid dont know much about this sort of
stuff.
Where does the mixer shower get its hot and cold supplies from? Is
there a boost pump? Assuming the hot supply comes from the hot
cylinder, is this a dedicated supply for the shower, or shared with
all the hot taps?
Cold water from main tank in loft. Hot from tank in airing cupboard.
Dedicated supply for shower.
What type of heating/hot water system do you have? I assume that a
single boiler (gas or oil-fired etc.) heats both the water (via an
indirect coil in the hot is water cylinder) and the radiators? Is it
fully pumped or is the hot water circuit gravity (convection) fed?
Single boiler for water and heating. Heating is pump fed. Water
gravity (i think)??
What zone valves (e.g. single 3-port
mid-position diverter valve or 2-off 2-port zone valves etc.) do you
have?
Sorry, havent a clue. Any other questions, let me know.
Hope this helps, and I appreciate your time.
Red.
OK, we'll work with what we've got. If it's a gravity hot water and pumped
heating system, it works like this: For hot water only, the programmer turns
just the boiler on, and the water circulates through the large diameter
pipes by convection. For heating, it turns the boiler *and* the pump on -
with the hot water continuing to get hot by convection, and with the pump
circulating water through the smaller pipes to the radiators. In theory,
water will only circulate through the radiators when the pump is running. In
practice, some systems continue to circulate by convection (particularly the
upstairs radiators) even when the pump isn't running. The cure for this is
to insert a "null-flow" valve in the CH circuit - which requires a slight
pressure to open it. It will open when the pump is running, but but will
stop convection from occurring.
Better still, convert it to a C-Plan (see
http://content.honeywell.com/uk/homes/systems.htm ) by putting a motorised
valve and cylinder stat in the hot water circuit. This provides a boiler
interlock - so that the boiler only comes on when required - saving energy.
Now to the shower. You say this has a dedicated hot feed. It presumably uses
a Surrey Flange or somesuch, which takes water out of the cylinder lower
down than the main feed to the hot taps? If for some reason, only the top
part of the tank is hot - maybe the boiler timer isn't on as long in the
summer? - this will draw cooler water from lower down, even though the
ordinary taps are receiving hot water. If this is the problem, you need to
make sure that the whole tank is hot - not just the top bit - probably by
running the boiler for longer.
When this problem occurs, what happens if you turn the mixer to full hot? Do
you get coolish water coming out, or nothing?
--
Cheers,
Set Square
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