Any CH wiring experts out there!

Current heating wiring was put in by someone who practiced creative wiring -
hence no wiring centre

System is semi gravity

There is a switched live on the programmer./thermo stat for CH ON or HW ON.
Output goes live when heat called for. There are output for live when off
(ie. spdt) but these are currently not connected.

When HW ON - there is power to Swl L in the boiler and the boiler fires up.

When CH ON - there is power to L in the boiler and the pump runs (no boiler)
and Swl L is off. Pump is connected to the boiler

When HW & CH is on, the pump runs and the boiler is fired. (i.e we get
central heating and HW)


We therefore have the following situation:

Both CH & HW On we get Hot Water and Heating - i.e OK
If HW Only is on: We get Hot Water - No Heating i.e OK
If only CH Only is on: We get Pump Only i.e
Problem


I cannot wire the CH On output to Swl as it would work backwards - i.e HW On
we would then get pump.

How can this be rewired to give CH Only. I reaslise that there is currently
no valve on the system, so HW temp control is only provided when in HW only
mode. If CH is running then there is no control of HW temp.

How should a valve be wired in to given addtional control?

I cannot wire the CH On output to Swl as it would work backwards - i.e HW
On
we would then get pump.

There is usually a zone valve with an additional switch that fires up the
boiler in parallel with the hot water system.

Alternatively, a relay may be used.

How can this be rewired to give CH Only. I reaslise that there is
currently
no valve on the system, so HW temp control is only provided when in HW
only
mode. If CH is running then there is no control of HW temp.

This depends on your boiler. Some boilers require an open loop through the
hot water cylinder to dump heat. Some require careful routing of pipework to
ensure emergency venting and quenching water supply. Some don't care at all,
enabling you to place zone valves on the hot water circuit. What is possible
depends on the boiler design.

Christian.

In an earlier contribution to this discussion,
Pete wrote:

Any CH wiring experts out there!

Current heating wiring was put in by someone who practiced creative
wiring - hence no wiring centre

System is semi gravity

There is a switched live on the programmer./thermo stat for CH ON or
HW ON. Output goes live when heat called for. There are output for
live when off (ie. spdt) but these are currently not connected.

When HW ON - there is power to Swl L in the boiler and the boiler
fires up.

When CH ON - there is power to L in the boiler and the pump runs (no
boiler) and Swl L is off. Pump is connected to the boiler

When HW & CH is on, the pump runs and the boiler is fired. (i.e we get
central heating and HW)


We therefore have the following situation:

Both CH & HW On we get Hot Water and Heating - i.e OK
If HW Only is on: We get Hot Water - No Heating i.e OK
If only CH Only is on: We get Pump Only
i.e Problem


I cannot wire the CH On output to Swl as it would work backwards -
i.e HW On we would then get pump.

How can this be rewired to give CH Only. I reaslise that there is
currently no valve on the system, so HW temp control is only provided
when in HW only mode. If CH is running then there is no control of HW
temp.

How should a valve be wired in to given addtional control?

With a conventional semi-gravity system, you *cannot* have CH only - because
when the boiler is on for the CH, it automatically heats the hot water too!
The HW switch controls the boiler amd the CH switch controls the pump -
usually via a room stat - but the boiler has to be forced on for CH to work.
Many programmers have an internal link which needs to be left in place on
such systems - which effectively turns HW on whenever CH is turned on.

If your gravity HW system heats the water fast enough, your best solution -
rather than going fully pumped - is to convert it to a C-Plan. [See
http://content.honeywell.com/uk/homes/systems.htm ]

For this you will need a 2-port zone valve and a tank stat on the hot water
cylinder (if you don't already have one). This gives truly independent
control over CH and HW, and also provides a boiler interlock so that the
boiler only fires when either or both circuits require heat - and shuts down
when both demands are satisfied (i.e. when both stats are open) thus saving
fuel.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

If your gravity HW system heats the water fast enough, your best
solution -
rather than going fully pumped - is to convert it to a C-Plan. [See
http://content.honeywell.com/uk/homes/systems.htm ]

For this you will need a 2-port zone valve and a tank stat on the hot
water
cylinder (if you don't already have one). This gives truly independent
control over CH and HW, and also provides a boiler interlock so that the
boiler only fires when either or both circuits require heat - and shuts
down
when both demands are satisfied (i.e. when both stats are open) thus
saving
fuel.

Looks like order a "2 port valve then"

An I right in thinking that to wire I need to:

Connect thermostat HW On to: Valve Brown
Permanent Live to: Valve Grey
thermostat CH On: Valve White and Pump L

Boiler L to Valve Orange

plus neutral & earth


Thus, boiler gets power when valve activated (via grey)
Boiler gets power when valve off (via valve white)

Currently the boiler has a connection for the pump. I assume that this
should be left so that the pump can continue to run when the tank
theremostat is cycling.

Looks like order a "2 port valve then"

Before designing the system you need to determine

(a) Will your boiler be safe with a valve on the hot water circuit. Some
older boilers (and most more recent solid fuel ones) will not be safe.

(b) Will the planned circuit still be safe in terms of boiler venting and
water supply? If not, is an alternative pipe routing possible?

Christian.

"Christian McArdle" wrote in message
. net...
Looks like order a "2 port valve then"

Before designing the system you need to determine

(a) Will your boiler be safe with a valve on the hot water circuit. Some
older boilers (and most more recent solid fuel ones) will not be safe.

Checked boiler manual and it shows an "optional" zone valve on the CH
circuit. Boiler is not too old (potterton profile)

(b) Will the planned circuit still be safe in terms of boiler venting and
water supply? If not, is an alternative pipe routing possible?

Valve would not affect venting/feed.

In additional there is an overheat thermostat on the boiler.

In additional there is an overheat thermostat on the boiler.

Sounds good. You can consider a valveless double pump system as well, if you
prefer. It was done recently, although I can't remember the thread title. It
involved various ingeneous ways of reducing the number of relays required...

Christian.

In an earlier contribution to this discussion,
Pete wrote:

If your gravity HW system heats the water fast enough, your best
solution -
rather than going fully pumped - is to convert it to a C-Plan. [See
http://content.honeywell.com/uk/homes/systems.htm ]

For this you will need a 2-port zone valve and a tank stat on the hot
water
cylinder (if you don't already have one). This gives truly
independent control over CH and HW, and also provides a boiler
interlock so that the boiler only fires when either or both circuits
require heat - and shuts down
when both demands are satisfied (i.e. when both stats are open) thus
saving
fuel.

Looks like order a "2 port valve then"

An I right in thinking that to wire I need to:

Connect thermostat HW On to: Valve Brown
Permanent Live to: Valve Grey
thermostat CH On: Valve White and Pump L

Boiler L to Valve Orange

plus neutral & earth


Thus, boiler gets power when valve activated (via grey)
Boiler gets power when valve off (via valve white)

Currently the boiler has a connection for the pump. I assume that
this should be left so that the pump can continue to run when the tank
theremostat is cycling.

The wire colours may vary, but if you study the Honeywell wiring diagram
referenced earlier, and wire it *functionally* the same way, you should ok.

As Christian has said, make sure that the boiler doesn't mind zone valves -
and that you install the valve in a position which doesn't interfere with
the un-interrupted vent and fill functions. A good place is in the HW flow
pipe very close to the hot cylinder *after* the point where the vent pipe
connects.

I'm a bit puzzled by your reference to a pump connection on the boiler. This
normally only applies to fully pumped systems, and keeps the pump running
for a bit after the boiler has stopped firing in order to stop the residual
heat in the boiler's metalwork from causing it to overheat. With a gravity
system, the boiler needs to be able to take care of itself in HW-only mode -
where the pump doesn't run at all. Are you *sure* it is a gravity system? If
so, please clarify how the pump is currently connected and what, if
anything, the boiler's pump connection is used for.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

I'm a bit puzzled by your reference to a pump connection on the boiler.
This
normally only applies to fully pumped systems, and keeps the pump running
for a bit after the boiler has stopped firing in order to stop the
residual
heat in the boiler's metalwork from causing it to overheat. With a gravity
system, the boiler needs to be able to take care of itself in HW-only
mode -
where the pump doesn't run at all. Are you *sure* it is a gravity system?
If
so, please clarify how the pump is currently connected and what, if
anything, the boiler's pump connection is used for.

Just come down from the loft. It is definatly a gravity system.

The boiler is fully pumped/gravity switchable which may account for the pump
outputs in the boiler wiring.

After a bit of a playaround, as far as I can see if power is put to the Swl
input - just the boiler fires up (i.e we get HW only)

If power is provided to the "L" input then just the pump runs

If power is provided to "L" input AND "Swl" input then boiler and pump run
(i.e we get heating AND water)

As far as I can see the pump is wired directly to the boiler pump output -
with no other connections.

In an earlier contribution to this discussion,
Pete wrote:

Are you *sure* it is a gravity system?


Just come down from the loft. It is definatly a gravity system.


How does looking in the loft prove that it's a gravity system? I wonder
whether we mean the same thing by "gravity system".

I am talking about gravity (or natural convection) circulation within the
*primary* hot water circuit. If this is what you have, you will probably
have *four* water pipes connected to your boiler - 2 large (28mm) ones which
go to the indirect coil in the hot water cylinder, and two smaller ones
(22mm) for the central heating - with the pump being somewhere in that
smaller circuit - and with the primary flow in the HW circuit being
*unpumped*. Is that what you've got?

[I wonder whether you're defining "gravity system" in terms of having a
large header tank for the hot water system - so that hot water flows by
gravity (rather than by mains pressure) to the hot taps. If this is the
case, we could be at cross-purposes, and may need to start again!]
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Pete wrote:

Are you *sure* it is a gravity system?

99.9% sure. HW circuit is not pumped, only central heating - see below.


How does looking in the loft prove that it's a gravity system? I wonder
whether we mean the same thing by "gravity system".

I am talking about gravity (or natural convection) circulation within the
*primary* hot water circuit. If this is what you have, you will probably
have *four* water pipes connected to your boiler - 2 large (28mm) ones
which
go to the indirect coil in the hot water cylinder, and two smaller ones
(22mm) for the central heating - with the pump being somewhere in that
smaller circuit - and with the primary flow in the HW circuit being
*unpumped*. Is that what you've got?

Not quite. I have TWO 28mm pipes going to the boiler. These 28mm pipes form
the HW flow and return.

From the 28mm flow there is a T piece and a 22mm pipe connecting to the pump
and then continuing to the CH flow.

CH return connects from a 22mm pipe to the 28mm Return via a T.

Is this still what you mean by gravity. - Would a diagram help?

In an earlier contribution to this discussion,
Pete wrote:

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Pete wrote:

Are you *sure* it is a gravity system?

99.9% sure. HW circuit is not pumped, only central heating - see
below.


How does looking in the loft prove that it's a gravity system? I
wonder whether we mean the same thing by "gravity system".

I am talking about gravity (or natural convection) circulation
within the *primary* hot water circuit. If this is what you have,
you will probably have *four* water pipes connected to your boiler -
2 large (28mm) ones which
go to the indirect coil in the hot water cylinder, and two smaller
ones (22mm) for the central heating - with the pump being somewhere
in that smaller circuit - and with the primary flow in the HW
circuit being *unpumped*. Is that what you've got?

Not quite. I have TWO 28mm pipes going to the boiler. These 28mm
pipes form the HW flow and return.

From the 28mm flow there is a T piece and a 22mm pipe connecting to
the pump and then continuing to the CH flow.

CH return connects from a 22mm pipe to the 28mm Return via a T.

Is this still what you mean by gravity. - Would a diagram help?



I can picture it from your description without requiring a diagram.

It certainly sounds as if you have a gravity HW and pumped CH system - with
two independent circuits which share a bit of pipe close to the boiler
rather than being separately connected to the boiler.

If you go for a C-plan system, connect the pump as per the C-plan circuit
diagram rather than leaving it connected to the boiler.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

If you go for a C-plan system, connect the pump as per the C-plan circuit
diagram rather than leaving it connected to the boiler.

I'd convert to S-Plan fully pumped, myself. Sounds like a fairly simple job.
It might even be possible to go sealed pressurised at the same time.

Christian.

Right - new problem (but I think I know the solution)

Just got the 2 port valve, and when having a look at the wire noticed that
the white didnt have an inner core (just a the plastic covering).

After checking the lid of the valve the diagram shows there is a microswitch
which just connects grey and orange when the valve is open, thus we can fire
the boiler when the HW is ON.

Am I right in thinking that this valve cannot be used without the NC link to
the pump heating?

After opening up the valve, I note that the "dummy" white cable is cut
short. I then consider swapping the relay for a SPDT, and after looking find
that one is already fitted but not wired? (why???)

I cannot connect the white wire as it is a dummy! so will need to replace
the 1m or so of flex to make a connection to the white.









For this you will need a 2-port zone valve and a tank stat on the hot
water cylinder (if you don't already have one). An I right in thinking
that to wire I need to:

Connect thermostat HW On to: Valve Brown
Permanent Live to: Valve Grey
thermostat CH On: Valve White and Pump L

Boiler L to Valve Orange

plus neutral & earth


Thus, boiler gets power when valve activated (via grey)
Boiler gets power when valve off (via valve white)

Currently the boiler has a connection for the pump. I assume that
this should be left so that the pump can continue to run when the tank
theremostat is cycling.

The wire colours may vary, but if you study the Honeywell wiring diagram
referenced earlier, and wire it *functionally* the same way, you should
ok.

In an earlier contribution to this discussion,
Pete wrote:

Right - new problem (but I think I know the solution)

Just got the 2 port valve, and when having a look at the wire noticed
that the white didnt have an inner core (just a the plastic covering).

After checking the lid of the valve the diagram shows there is a
microswitch which just connects grey and orange when the valve is
open, thus we can fire the boiler when the HW is ON.

Am I right in thinking that this valve cannot be used without the NC
link to the pump heating?

After opening up the valve, I note that the "dummy" white cable is cut
short. I then consider swapping the relay for a SPDT, and after
looking find that one is already fitted but not wired? (why???)

I cannot connect the white wire as it is a dummy! so will need to
replace the 1m or so of flex to make a connection to the white.









For this you will need a 2-port zone valve and a tank stat on the
hot water cylinder (if you don't already have one). An I right in
thinking that to wire I need to:

Connect thermostat HW On to: Valve Brown
Permanent Live to: Valve Grey
thermostat CH On: Valve White and Pump L

Boiler L to Valve Orange

plus neutral & earth


Thus, boiler gets power when valve activated (via grey)
Boiler gets power when valve off (via valve white)

Currently the boiler has a connection for the pump. I assume that
this should be left so that the pump can continue to run when the
tank theremostat is cycling.

The wire colours may vary, but if you study the Honeywell wiring
diagram referenced earlier, and wire it *functionally* the same way,
you should ok.

If you're converting to a C-plan, the switch on the zone valve - which
operates when the valve opens - *needs* to be a changeover switch with NO,
NC and COM - otherwise it won't work. If your valve isn't like this, swap it
for one which *is*.

If, on the other hand, you're aiming at a fully-pumped S-plan system, with
*two* zone valves, the switches on those only need to be of the simple
on/off type.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
Pete wrote:

Right - new problem (but I think I know the solution)

Just got the 2 port valve, and when having a look at the wire noticed
that the white didnt have an inner core (just a the plastic covering).

After checking the lid of the valve the diagram shows there is a
microswitch which just connects grey and orange when the valve is
open, thus we can fire the boiler when the HW is ON.

Am I right in thinking that this valve cannot be used without the NC
link to the pump heating?

After opening up the valve, I note that the "dummy" white cable is cut
short. I then consider swapping the relay for a SPDT, and after
looking find that one is already fitted but not wired? (why???)

I cannot connect the white wire as it is a dummy! so will need to
replace the 1m or so of flex to make a connection to the white.


[Apologies for not trimming the earlier reply - thought I had! The question
and answer *should* have looked like this, will all the previous stuff
removed].

If you're converting to a C-plan, the switch on the zone valve - which
operates when the valve opens - needs to be a changeover switch with NO,
NC and COM - otherwise it won't work. If your valve isn't like this, swap it
for one which is.

If, on the other hand, you're aiming at a fully-pumped S-plan system, with
two zone valves, the switches on those only need to be of the simple
on/off type.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

take a look at the grunfos pump plan its a twin pump valve assembly see if
this will do the trick

"Pete" wrote in message
.uk...
Any CH wiring experts out there!

Current heating wiring was put in by someone who practiced creative
wiring -
hence no wiring centre

System is semi gravity

There is a switched live on the programmer./thermo stat for CH ON or HW
ON.
Output goes live when heat called for. There are output for live when off
(ie. spdt) but these are currently not connected.

When HW ON - there is power to Swl L in the boiler and the boiler fires
up.

When CH ON - there is power to L in the boiler and the pump runs (no
boiler)
and Swl L is off. Pump is connected to the boiler

When HW & CH is on, the pump runs and the boiler is fired. (i.e we get
central heating and HW)


We therefore have the following situation:

Both CH & HW On we get Hot Water and Heating - i.e OK
If HW Only is on: We get Hot Water - No Heating i.e OK
If only CH Only is on: We get Pump Only i.e
Problem


I cannot wire the CH On output to Swl as it would work backwards - i.e HW
On
we would then get pump.

How can this be rewired to give CH Only. I reaslise that there is
currently
no valve on the system, so HW temp control is only provided when in HW
only
mode. If CH is running then there is no control of HW temp.

How should a valve be wired in to given addtional control?