CH/HW Programmer wiring.

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Hello all,

I am replacing an old APL lifestyle LP241 programmer with a new Heatmiser TM4 touchscreen. On the old timer plate has wires for L, N, HW on, HW off and CH on (CH off wire is not connected for some reason) although it all works as it should.
The new programmer Only allows for L, N and switch lives for channels 1 - 4.
What do i do with the HW off wire???
I believe my system is a Y Plan from what i can see if this helps at all.

Many thanks
Richard
 
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in the instructions it should have a wiring guide also look on the back of the clock there is a diagram on most.
but the normal set up for a 2 channel is
1. hot water on
2. hot water off
3. central heating on
4. central heating off

2. is used on a Y plan (mid pos valve) and on S plan when the zone valve is motor on motor off
4. is only normally used on S plan with a motor on motor off valve
 
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Thank you Kevindgas for the very fast response,
Above is the only wiring diagram that accompanys the new TM4 unit.
I understand that the 'HW on' L will connect to the new switch live 1 and the 'CH on' will connect to the switch live 2.
Is it ok to leave the 'HW off' disconnected as i have my hot water on 24/7??
 
I am replacing an old APL lifestyle LP241 programmer with a new Heatmiser TM4 touchscreen. On the old timer plate has wires for L, N, HW on, HW off and CH on (CH off wire is not connected for some reason) although it all works as it should.
The new programmer Only allows for L, N and switch lives for channels 1 - 4.
What do i do with the HW off wire???
I believe my system is a Y Plan from what i can see if this helps at all.
If you have a Y plan, you will have one motorized valve, which looks like this:

View media item 5946.

A Y plan needs a connection to the programmer HW OFF (CH OFF is hardly ever used).

If you have a Y Plan, the TM4 is not suitable as it does not provide HW OFF. The only way round it would be to convert your system to an S Plan, which uses two valves like this, and does not need HW OFF connected.

View media item 11762
 
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Thank you DH,

I do have a Y plane with the 3 port mid position valve. Due to kitchen refurbishment i wanted to replace my old programmer. Heatmiser site did not inform for which plans there touch screen is and is not compatible with.
I do not want to change any valves or pipe work, just want a more modern fancy programmer. As the TM4 is not compatable could anyone suggest any alternatives, preferably touchscreen.

Regards
Richard
 
I do not want to change any valves or pipe work, just want a more modern fancy programmer. As the TM4 is not compatable could anyone suggest any alternatives, preferably touchscreen.
Why do you need a touch screen? More to go wrong.

Get a Honeywell or Drayton 2-channel timer.
 
As mentioned i have never turned my hot water off, the current timer is set to be 'ON' 24/7 and has not been switched off via the timer for over 4 years. for this reason could i not continue to install the TM4 and just leave the HW OFF terminal disconnected. Would this way work? if not does anybody know of any work arounds (not converting any pipe work or valves).

Regards

Richard
 
As mentioned i have never turned my hot water off, the current timer is set to be 'ON' 24/7 and has not been switched off via the timer for over 4 years. for this reason could i not continue to install the TM4 and just leave the HW OFF terminal disconnected. Would this way work? if not does anybody know of any work arounds (not converting any pipe work or valves).
I suppose you could do it, but it would not be a "pure" Y plan.

Here's a brief ;) explanation of how the Y plan works.

When HW only is called for, the valve is not energised so it is stays in the HW port (B) open position. The boiler is lit by the HW cylinder thermostat.

If CH is called for at the same time as HW, the CH thermostat applies a voltage to the white wire of the valve. This causes the valve to go to mid-position (ports A and B open) and stop there (how is another story). The boiler is still lit via the HW thermostat.

When HW is satisfied the HW thermostat switches over and applies a voltage to the valves grey wire. This causes the valve to move to the CH only position (port A open). The boiler is then lit via the valve.

On a "normal" Y Plan, there is also a wire from the timer HW OFF terminal to the grey wire, so CH only can be invoked either when HW reaches temperature or when HW is turned off at the programmer.

Provided you have a wire from the HW thermostat's SAT terminal to the valve's grey wire you should be OK.
 
looking at the wiring adjacent to the boiler i can see that from the tank thermostat i have:

Brown wire connected to the 230V supply
Black wire which is connected via the junction box to the pump brown wire and valve orange wire.
Blue wire connects to the grey valve wire.
 
looking at the wiring adjacent to the boiler i can see that from the tank thermostat i have:

Brown wire connected to the 230V supply
Black wire which is connected via the junction box to the pump brown wire and valve orange wire.
Blue wire connects to the grey valve wire.
That's OK then.

Just wire up your fancy new programmer and ignore the missing HW OFF wire.

Just had a thought :idea:

If you keep you HW on 24/7, why do you need to connect it to the new programmer? Just connect the brown wire to a permanent Live in the junction box.

Think some more :idea: , why do you need a four channel programmer when you will only be using one channel?
 
Thank you so much D_Hailsham, i relay do appreciate all your help and advice.

PS. touch screen only available in 4 channel.

Once again many thanks.

Regards

Richard
 

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