kiich wrote:

3) programmer - boiler programmer set to CONSTANT; heather immersion
timer set to ON with the over-ride switch, but this i was told by
Dave(see previous reply) that is a backup - but if so, why is it there?

As per my last post, check to see if you actually have a immersion
heater. If you have, AND this timer box is connected to it - this it is
like Dave said - a backup.

If however it is being used as a timer to drive the boiler and hot water
heating circuit then it may come into play here. If that is the case
then having it demanding heat may take priority over the heating.

This is ofen done in bathrooms to
ensure that heated towel rails etc. remain heated even during the summer when most people have the heating turned off.


Kiichi that is exactly what happens - it is actually a towel rail i
think but a big one so i thought it was a heater of some sort. so when
boiler comes on, it gets hot - it eventually stops getting hot and the
boiler also is off at the same time.

That makes sense - you run some hot water, the cylinder stat calls for
heat and the boiler runs. The towel rail is in the path of this water
being directed to the cylinder and so gets hot. Once the hot water is
back up to temperature the boiler shuts off and the rads cool down. For
the purposes of any further investigation you may find you can ignore
the towel rads since it looks like they are not a part of the actual
heating circuit.

Kiichi Hmmm - so how do i check that? when you say "valve", you mean
the valve next to the water pump, right? i will get details tonight

Yup. There may be others.

Common types for a simple Y plan setup are mid position valves which can
direct water to either port or split it between both equally; or a
simpler diversion valve which can go one way or the other but has no mid
position and hence can do hot water or heating but not both. Hot water
would usually take priority in these cases. Having a look at the number
of wires that connect to it wil be a clue (assuming the label on it does
not say!). You need five for a mid position valve but only three for a
diversion one.

If it were not working the boiler would very quickly shut down with an overheat fault detected.


kiichi how quickly? i ask because my boiler does turn off after a
while but thats because i'm not using hot water right?

Under a minute! With the pump not working it will be pumping kW of heat
into a couple of pints of water in its heat exchanger. That will get
very hot very quickly without any circulation.

For an entertaining account of what happens when this occurs along with
a failure of some other protective bits of the boiler read he

http://www.diyfaq.org.uk/humour.html#uninstalling

For more general background read soem of this:

http://www.diyfaq.org.uk/plumbing/plumbingpage1.html


Again depends on the type of valve. Many have controls that enable them to be manually set in the absense of any external control (or a failure of the electronics/motor in the valve)


Kiichi will check for this tonight. can i just turn this control
using a screw driver or by hand?

It is usually a leaver that can be moved by hand (assuming the valve has
not siezed)

if it is control settings, why doesnt having all programmers set to
CONSTANT and thermostat to the highest settings make the CH work then?

If your system prioritises hot water over heating and your cylinder stat
is set high enough, you may never reach a position where the demand for
hot water heating is reached and hence the heating does not get a look in.

Is this timer connected to the boiler? Does your cylinder have a
immersion heater? (the top of which would normally be visible sticking out the cylinder - it would also have to have wires connecting to it).


kiichiyou mean the programmer/timer underneath the boiler? if so,
YES.

The 7 day immersion timer/programmer is connected to that one - but
doesnt seem to make any difference whatever settings i make it to do.

This is what makes me susspect it may have nothing to do with an
immersion heater. (if it were just for the immersion then it would not
actually need any connection with the boiler (unless there is some form
of interlock to prevent both operating at once).

kiichi
how do i know that i dont have immersion heater? i cant see one in the
flat - so i guess i dont??

Look at your hot water cylinder... any wires connected to it? if not
then no immersion heater. (also look at your consumer unit - see if
there is a fuse/mcb labelled immersion or something like that).

if the immersion heater programmer is indeed used as a time switch
facility to the boiler (via the old looking boiler programmer), how
come it doesnt do anything to the boiler when i set it to ON using the
over-ride on the immersion heater timer??

When set to on it would enable control of the boiler and pump by the
cylinder stat - you wont be able to force it to run if there is no
demand for heat. Once set to off the cylinder stat ought to be out of
the equation.



Are you sure it is the same pump being used for both bathrooms? You may have another somewhere else.


kiichi yes. i turn the tap on, go and check the pump and it is
buzzing away.

It could be that the twin pump is driving both hot and cold - hot has
been plumber after the pump in both bathrooms, but the cold only plumbed
after the pump to one. (the other may use mains cold)

i dont think it is flopping about - just sitting there.
the noise isnt just from the vibration - it is also from the pump
itself (if you know what i mean) but i will try and put some rubber etc
under neath it

if i do that, can i do it without do anything to the pipes coming into
the shower pump?? would that not damage the pipes??

There will usually be a little "give" in the pipework that will
accommodate a little bit of extra padding. Depends a bit on how it s done.

--
Cheers,

John.

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