Could someone check the wiring on my evil plan to fit a cylinder thermostat
to a system that doesn't currently have one fitted.

The wiring currently is:

http://www.puppet-head.co.uk/Wiring.jpg

and the pipework is a simple loop through the cylinder that extends through
the heating when the value opens.

Can I just add the thermostat into the line currently shown between 16 and
3 on the diagram, and then join 8 to 3 to enable the heating to work when
the cylinder thermostat is off?

Cheers

Steve

On 10 May, 23:08, Steve wrote:

Could someone check the wiring on my evil plan to fit a cylinder thermostat
to a system that doesn't currently have one fitted.

The wiring currently is:

http://www.puppet-head.co.uk/Wiring.jpg

and the pipework is a simple loop through the cylinder that extends through
the heating when the value opens.

Can I just add the thermostat into the line currently shown between 16 and
3 on the diagram, and then join 8 to 3 to enable the heating to work when
the cylinder thermostat is off?

Cheers

Steve

Fitting a thermostat can't achieve that, you'd need to change the
plumbing. But I'm not sure theres much point in doing anything, what
exactly is the problem?


NT

In an earlier contribution to this discussion,
Steve wrote:

Could someone check the wiring on my evil plan to fit a cylinder
thermostat to a system that doesn't currently have one fitted.

The wiring currently is:

http://www.puppet-head.co.uk/Wiring.jpg

and the pipework is a simple loop through the cylinder that extends
through the heating when the value opens.

Can I just add the thermostat into the line currently shown between
16 and 3 on the diagram, and then join 8 to 3 to enable the heating
to work when the cylinder thermostat is off?

Cheers

Steve

I struggling a bit to work out just what you've got. What is the valve - is
it a motorised diverter valve which enables you to have CH or HW but not
both at the same time?

If so, what you have is essentially a W-Plan system, and needs to be wired
as per the W-Plan diagram shown at
http://content.honeywell.com/uk/homes/systems.htm

Or is it a gravity HW and pumped CH system? If so, you need to look at the
C-Plan section of the Honeywell page referenced above.
--
Cheers,
Roger
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On 11 May, 13:44, "Roger Mills" wrote:
In an earlier contribution to this discussion,
Steve wrote:

Could someone check the wiring on my evil plan to fit a cylinder
thermostat to a system that doesn't currently have one fitted.

The wiring currently is:

http://www.puppet-head.co.uk/Wiring.jpg

and the pipework is a simple loop through the cylinder that extends
through the heating when the value opens.

Can I just add the thermostat into the line currently shown between
16 and 3 on the diagram, and then join 8 to 3 to enable the heating
to work when the cylinder thermostat is off?

Cheers

Steve

I struggling a bit to work out just what you've got. What is the valve - is
it a motorised diverter valve which enables you to have CH or HW but not
both at the same time?

If so, what you have is essentially a W-Plan system, and needs to be wired
as per the W-Plan diagram shown athttp://content.honeywell.com/uk/homes/systems.htm

Or is it a gravity HW and pumped CH system? If so, you need to look at the
C-Plan section of the Honeywell page referenced above.

AIUI he seems to have an older arrangement that is plumbed so that
boiler output always goes thru HW first,. then may or may not go thru
CH circuit. So HW temp is less well controlled than on modern systems.

I'm not clear what problem this is causing. Since an old cylinder will
have relatively low transfer rate, the CH cct will still see hot water
right away, though a bit below peak temp at first. If the HW cyl lacks
a stat then I guess during HW only operation, the pump will keep
running and the boiler stat will control the HW temp. Which seems
quite workable.


NT

In an earlier contribution to this discussion,
wrote:


AIUI he seems to have an older arrangement that is plumbed so that
boiler output always goes thru HW first,. then may or may not go thru
CH circuit. So HW temp is less well controlled than on modern systems.

I'm not clear what problem this is causing. Since an old cylinder will
have relatively low transfer rate, the CH cct will still see hot water
right away, though a bit below peak temp at first. If the HW cyl lacks
a stat then I guess during HW only operation, the pump will keep
running and the boiler stat will control the HW temp. Which seems
quite workable.


NT

So what does the 'valve' do? I presume it would have to direct the output
fom the cylinder either back to the boiler (HW only) or through the
radiators (HW + CH). The mind boggles! Is it likely to be a single pipe CH
system?

The problem with a system like that is that the HW will reach boiler
temperature whenever the CH is on. So it's not possible to control the HW to
60 decC while feeding 80 deg C water to the radiators - you either have
*very* hot HW or coolish radiators.

I presume that the cylinder stat would only be effective in HW-only mode?
Whether the wiring arrangement suggested by the OP would work or not, I
don't know - I guess it may need some additional relay logic.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On 11 May 2007 06:11:35 -0700, wrote:

On 11 May, 13:44, "Roger Mills" wrote:
[28 quoted lines suppressed]

AIUI he seems to have an older arrangement that is plumbed so that
boiler output always goes thru HW first,. then may or may not go thru
CH circuit. So HW temp is less well controlled than on modern systems.

Correct


I'm not clear what problem this is causing. Since an old cylinder will
have relatively low transfer rate, the CH cct will still see hot water
right away, though a bit below peak temp at first. If the HW cyl lacks
a stat then I guess during HW only operation, the pump will keep
running and the boiler stat will control the HW temp. Which seems
quite workable.

The problem is that the boiler is on when it doesn't need to be, the boiler
is in the garage so there is a large loop that will cool down quite fast
and the boiler keeps trying to re-heat that loop. Even with the timing
reduced it's still heating for no reason.

Why wouldn't fitting the thermostat in the manner I suggested work?(I have
no experience in heating setup, and all the plan diagrams on the internet
do not cover this system)

Steve

On Fri, 11 May 2007 18:07:58 +0100, Roger Mills wrote:


So what does the 'valve' do? I presume it would have to direct the output
fom the cylinder either back to the boiler (HW only) or through the
radiators (HW + CH). The mind boggles! Is it likely to be a single pipe CH
system?

I'm not sure exactly how the value makes the flow go through the raditors,
it just opens the larger loop. I would have thought that the water would
take the easier route back to the boiler and not go this extra route but it
does.


The problem with a system like that is that the HW will reach boiler
temperature whenever the CH is on. So it's not possible to control the HW to
60 decC while feeding 80 deg C water to the radiators - you either have
*very* hot HW or coolish radiators.

I presume that the cylinder stat would only be effective in HW-only mode?
Whether the wiring arrangement suggested by the OP would work or not, I
don't know - I guess it may need some additional relay logic.

I'm not worried about CH always heating the HW, thats fine, I just want to
cut off the boiler when I don't need it for HW or CH.

Steve