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keith
 
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Default central heating not working - or is it just a setting

Please can someone help me tell if our CH is faulty or if i've just got the
settings wrong?
There are more knobs to fiddle with on than the CH in our previous house &
I'm not sure what thay do or how they interact.
Pictures at :

www.dulwich.net/ch

CH works OK during day on timer, but seems to "go to sleep" at night (even
when timer says ON and thermostat is calling) and won't get radiators warm.
Also doesnt start warm in the morning. Plenty hot during day!

I've managed to "wake it up" last 2 nights by 1-Switching programmer on &
off at mains or 2- turning up the knob on the water tank.

I can work the thermostat and timer (just like old house) but this one also
has a big knob 0-5 on the gas heater (see pictures) which makes the gas
flame appear & go higher sometimes, other times turning it up has no
effect - no flame to be seen.

What is this knob supposed to do & what should I be doing with it & how does
it interact with the knob on the water tank, which I think is the water
temperature?
(see pictures)

Have I got one of these knobs too high or something to cause the problem?

Thanks


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Set Square
 
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In an earlier contribution to this discussion,
keith wrote:

Please can someone help me tell if our CH is faulty or if i've just
got the settings wrong?
There are more knobs to fiddle with on than the CH in our previous
house & I'm not sure what thay do or how they interact.
Pictures at :

www.dulwich.net/ch

CH works OK during day on timer, but seems to "go to sleep" at night
(even when timer says ON and thermostat is calling) and won't get
radiators warm. Also doesnt start warm in the morning. Plenty hot
during day!

I've managed to "wake it up" last 2 nights by 1-Switching programmer
on & off at mains or 2- turning up the knob on the water tank.

I can work the thermostat and timer (just like old house) but this
one also has a big knob 0-5 on the gas heater (see pictures) which
makes the gas flame appear & go higher sometimes, other times turning
it up has no
effect - no flame to be seen.

What is this knob supposed to do & what should I be doing with it &
how does it interact with the knob on the water tank, which I think
is the water temperature?
(see pictures)

Have I got one of these knobs too high or something to cause the
problem?

Thanks


It sounds from what you say that the radiators only get hot when there is
*also* a demand for domestic hot water. Has it ever worked properly? If not,
it has not been installed and/or wired correctly. From your photos, you have
a Y-Plan system - fully pumped, with a mid-position 3-port valve to direct
the water to the cylinder and/or radiators. [See
http://content.honeywell.com/uk/homes/systems.htm and scroll down to Y-Plan]

This system requires the programmer to have a "HW Off" terminal in addition
to "HW On" and "CH On" and it also requires the cylinder stat to have
change-over contacts. If this is not done, the system won't work in CH-only
mode.

If it *has* worked but has since stopped working, my money would be on a
duff microswitch in the actuator on the 3-port valve. In the CH-only
position (with HW turned off or satisfied) the system relies on this
microswitch to turn the boiler and pump on.

Incidentally, the knob on the boiler only controls the temperature of the
water produced by the boiler - unless you turn it right off - not whether it
operates or not. Your problem is either in the wiring or in the actuator.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.


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John
 
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"keith" wrote in message
...
Please can someone help me tell if our CH is faulty or if i've just got
the settings wrong?
There are more knobs to fiddle with on than the CH in our previous house
& I'm not sure what thay do or how they interact.
Pictures at :

www.dulwich.net/ch

CH works OK during day on timer, but seems to "go to sleep" at night (even
when timer says ON and thermostat is calling) and won't get radiators
warm. Also doesnt start warm in the morning. Plenty hot during day!

I've managed to "wake it up" last 2 nights by 1-Switching programmer on &
off at mains or 2- turning up the knob on the water tank.

I can work the thermostat and timer (just like old house) but this one
also has a big knob 0-5 on the gas heater (see pictures) which makes the
gas flame appear & go higher sometimes, other times turning it up has no
effect - no flame to be seen.

What is this knob supposed to do & what should I be doing with it & how
does it interact with the knob on the water tank, which I think is the
water temperature?
(see pictures)

Have I got one of these knobs too high or something to cause the problem?

Thanks


I'd guess that if you look (usually in the airing cupboard) you will find a
motorised valve with three pipes into it and a metal or plastic box
containing the drive motor attached to it. Possibly the motor has died at
some time and someone has pushed the drive unit override lever across into
the manual position which sets the valve to pass hot boilerwater to both
cylinder and radiators. As the motor does not drive the valve all the way
across the internal limit switch does not operate to call the pump and
boiler into life. Turning up the water thermostat or running off some hot
water thus calling for heat to the cylinder does ask the boiler and pump to
operate and so you get heat to your rads.
See the faqs for Y plan systems. Replacing the failed motor is a fairly
trivial job and inexpensive
Of course you could have an incorrectly wired system (g)


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keith
 
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......... Possibly the motor has died at
some time and someone has pushed the drive unit override lever across into
the manual position which sets the valve to pass hot boilerwater to both
cylinder and radiators. As the motor does not drive the valve all the way
across the internal limit switch does not operate to call the pump and
boiler into life. Turning up the water thermostat or running off some hot
water thus calling for heat to the cylinder does ask the boiler and pump
to operate and so you get heat to your rads.
............

Thanks for replying, I've spotted there's yet another control which I think
is the one you're refering to as it's on the valve.
It slides from "Auto" at one end to "Mid" at the other. It looks like you
can take a diversion on the way to Mid and go to an alternative position
instead. There's a picture that calls this "Manual Override Only".
The slider is set to "Auto" which I think you're saying is correct. (see
valveswitch picture at www.dulwich.net/ch)
Should it be set to one of the other settings?

Thanks



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John
 
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"keith" wrote in message
...

........ Possibly the motor has died at
some time and someone has pushed the drive unit override lever across
into the manual position which sets the valve to pass hot boilerwater to
both cylinder and radiators. As the motor does not drive the valve all
the way across the internal limit switch does not operate to call the
pump and boiler into life. Turning up the water thermostat or running off
some hot water thus calling for heat to the cylinder does ask the boiler
and pump to operate and so you get heat to your rads.
............

Thanks for replying, I've spotted there's yet another control which I
think is the one you're refering to as it's on the valve.
It slides from "Auto" at one end to "Mid" at the other. It looks like you
can take a diversion on the way to Mid and go to an alternative position
instead. There's a picture that calls this "Manual Override Only".
The slider is set to "Auto" which I think you're saying is correct. (see
valveswitch picture at www.dulwich.net/ch)
Should it be set to one of the other settings?


If its at auto then the chances are that the valve motor is ok if you are
getting heating sometimes. However there is still a possibility that your
motor has seized up with the valve open. Try switching off all power to the
heating system and then going to the valve to assess if the lever is now
"free" or requires pushing across against the spring to move the valve. Put
the power back on and set the programmer and roomstat to heat required
lightly touching against the lever and listening whilst doing this (you may
need an assistant). If the valve is ok you should hear the motor and feel
the lever follow the drive from hot water only to the heating position.
If the valve is ok then the problem will require further tracing.




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Nick Atty
 
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On Mon, 20 Dec 2004 22:25:32 -0000, "Set Square"
wrote:

It sounds from what you say that the radiators only get hot when there is
*also* a demand for domestic hot water. Has it ever worked properly? If not,
it has not been installed and/or wired correctly. From your photos, you have
a Y-Plan system - fully pumped, with a mid-position 3-port valve to direct
the water to the cylinder and/or radiators. [See
http://content.honeywell.com/uk/homes/systems.htm and scroll down to Y-Plan]

This system requires the programmer to have a "HW Off" terminal in addition
to "HW On" and "CH On" and it also requires the cylinder stat to have
change-over contacts. If this is not done, the system won't work in CH-only
mode.


When I moved in here I found a superb CH system, with the most amazingly
crap wiring system imaginable.

The house was divided into three zones, so there are four 2-port valves.
There is a hot water/CH timer. There are no thermostats anywhere in
the house, not even on the tank.

When the hot water part of the timer is on, it fires up the pump and the
hot water valve. When the CH part is on it goes through three switches
on a very nice, custom made and labelled, switch panel to the three zone
valves. The boiler is on all the time.

To keep things "tidy", the installer had carefully removed the
multi-core cable from the valves and replaced it with 3 core, not using
the microswitches at all.

I'm still speechless thinking about it.

We now have three room thermostats, each turning on the appropriate 3
port valve, as does the new tank stat. The four microswitches in the
valves have been reinstated to activate the boiler. The pump overrun
output from the boiler, which was previously u/c now runs the pump.
--
On-line canal route planner: http://www.canalplan.org.uk

(Waterways World site of the month, April 2001)
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