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Elizabeth Regan
 
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Default hot water / central heating problem

Please can anyone help.

I have a 7 day timer for my hot water and central heating. When I set the
timer for the central heating to come on, it does, but the hot water gets
hot...very hot (over 80 degrees)as well. No light on the timer comes on to
show the hot water is on. The hot water will come on with the timer when it
is set.

Having the hot water heat up everytime I have the central heating on is
causing the hot water to get very hot and the tank thermostat is not
stopping it. (For some reason there is a permanent live going to the
thermostat on the tank as well?) I have now burnt out 2 thermostats!

An electrician came to check the wiring in my timer and said it was all
fine. My plumber came several months ago and fitted a new motorized valve -
he put in a 6 wire one instead of a 5 wire (to replace the old 5 wire) -
there were no 5 wires available and he said it would make no
difference....BUT could this be the cause of my problem? OR could there be a
crossed wire between upstairs where the tank etc are and downstairs where
the timer is? Would a crossed wire cause the hot water to come on everytime
the central heating does?

Please help me someome. My plumber and electrician are completely stumped,
my daughter burned her arm badly in the boiling water and my gas bill is
rising!


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John Stumbles
 
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Default hot water / central heating problem

On Sat, 18 Mar 2006 13:44:27 +0000, Elizabeth Regan wrote:

Please can anyone help.

I have a 7 day timer for my hot water and central heating. When I set the
timer for the central heating to come on, it does, but the hot water gets
hot...very hot (over 80 degrees)as well. No light on the timer comes on to
show the hot water is on. The hot water will come on with the timer when it
is set.


Do you have a 3-port valve - something like this
http://www.toolstation.com/search.html?searchstr=60151
or 2 2-port valves, like
http://www.toolstation.com/search.html?searchstr=85125

The 3-port valve probably means you've got a 'Y' plan system, 2-port
valves are usually in an 'S'-plan system

(For some reason there is a permanent live going to the
thermostat on the tank as well?) I have now burnt out 2 thermostats!


There should only be a live when the programmer is calling for hot water

An electrician came to check the wiring in my timer and said it was all
fine. My plumber came several months ago and fitted a new motorized valve -
he put in a 6 wire one instead of a 5 wire (to replace the old 5 wire) -
there were no 5 wires available and he said it would make no
difference....BUT could this be the cause of my problem? OR could there be a
crossed wire between upstairs where the tank etc are and downstairs where
the timer is? Would a crossed wire cause the hot water to come on everytime
the central heating does?

Please help me someome. My plumber and electrician are completely stumped,
my daughter burned her arm badly in the boiling water and my gas bill is
rising!


Honeywell have wiring diagrams for many heating/HW configurations at
http://content.honeywell.com/uk/homes/systems.htm. However you may have to
interpolate between these diagrams and the actual components you have if
they're other makes than Honeywell. Unfortunately this is an area which
falls between the traditional skill areas of electricians and plumbers,
some of whom willbe thrown by something that's not straight out of the
book. It doesn't help that some CH systems seem to be pretty much thrown
together with wiring on choch-blocks crammed into a tiny wiring box with
no labelling which makes verifying the correctness of the setup, or fault
finding, very laborious. If this is outside your own competence you'll
have to find yourself a heating engineer who does understand such things.
It's not rocket-science, but as I say not every plumber groks it.


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John Stumbles
 
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Default hot water / central heating problem

On Sat, 18 Mar 2006 13:44:27 +0000, Elizabeth Regan wrote:

... the hot water gets
hot...very hot (over 80 degrees)as well. No light on the timer comes on to
show the hot water is on. The hot water will come on with the timer when it
is set.

....
Please help me someome. My plumber and electrician are completely
stumped, my daughter burned her arm badly in the boiling water and my
gas bill is rising!


Aside from what I said in my other post, if you turn down the thermostat
on your boiler it will reduce the temperature the hot water gets to
in your cylinder (and therefore your taps). Obviously this is only a
stop-gap until you get the system fixed properly. It will also reduce the
temperature of water in the radiators which may mean you don't get enough
heating when it's very cold outside, so you'll have to find a balance.
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John Rumm
 
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Default hot water / central heating problem

Elizabeth Regan wrote:

I have a 7 day timer for my hot water and central heating. When I set the
timer for the central heating to come on, it does, but the hot water gets
hot...very hot (over 80 degrees)as well. No light on the timer comes on to
show the hot water is on. The hot water will come on with the timer when it
is set.


OK there are several ways for this to be setup. but from your
description it sounds like you have a Y plan system:

http://content.honeywell.com/uk/homes/systems.htm

Hot water comes from the boiler to a three port valve, and then goes
either round the heating circuit, or the hot water circuit, and possibly
the option being split between both depending on if the valve can work
in a "mid position".

It sounds as if your valve is stuck[1]. Since you say the rads and the
hot water get hot then that would suggest it is stuck either in the mid
position on somewhere close to it.

Where is the valve? Is it easy to get at? If so, have a look at the
leaver on the side (most have one):

http://content.honeywell.com/uk/home...21%20V4073.pdf

That leaver can be used to lock the valve into the mid position (handy
for when the motor on it fails) so check it is not locked in that position.

[1] Stuck can mean many things:

a) The actual valve body (i.e. the water carrying bit) may be seized and
hence the motor on top is not able to turn it.

b) the motor may be dead

c) the wiring may have a fault

d) the thermostat on the cylinder may have a fault

A bit of detective work on your system will help identify which is at
fault. Can you set your programmer so that it asks for heating "Off" and
hot water "On". Do the rads then cool down? Is the hot water still
getting heated (a quick fondle of the pipe leaving the middle of the
cylinder should tell you).

If the rads do go off, then that tends to eliminate (a) and (b) since
the valve must have moved from mid to HW only position. If the system
used to work and nothing has changed, that makes (c) less likely. So my
money would be on (d) possibly with a bit of (c) mixed in!

If the cylinder stat was permanently calling for heat (and the wiring
neglected to put the programmer in series with the stat such that it can
override it and turn the HW heating off) then that could give you the
symptoms you describe. If you turn the dial on the cylinder stat do you
hear a click from it at any point?

What you do next depends a bit on how comfortable you are with a
multimeter and prodding at wires that may have mains on them.




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
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Roger Mills
 
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Default hot water / central heating problem

In an earlier contribution to this discussion,
John Stumbles wrote:


Honeywell have wiring diagrams for many heating/HW configurations at
http://content.honeywell.com/uk/homes/systems.htm


Whereas the most likely scenario is that it is Y-Plan system with a 3-port
valve which refuses - for either mechanical or electrical reasons - to move
to the CH-only position, the thought occurs to me that it might *just* be a
C-Plan system. This is a gravity HW/pumped CH system with a motorised valve
in the HW circuit to stop gravity circulation once the HW is up to
temperature. If the valve is wired incorrectly it could certainly cause the
reported symptoms.

To the OP: How many water pipes connect to the boiler, and what size are
they (22mm, 28mm etc.)? Where is the motorised valve? How many water
connections does it have? Where do the pipes go which connect to it?
--
Cheers,
Roger
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