Can you use twin channel programmer on C plan system?

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Hi All

I recently moved into a house with a Baxi back boiler and eventually worked out that it is a C plan system.
I originally had issues with hot water, but replacing the cylinder stat has sorted this out.

Todays question however is about replacing my single channel programmer.
I dont need the HW on all the time that the CH is on, so thought it would be better to limit the HW by timer, by replacing single channel with twin.

Is this possible with a C plan system?

Also, should my boiler be set to min/max or some where in between?

Thanks to those of you less ignorant than me that can help :D
 
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Chances are you have gravity hot water. In this case when the heating is on hot water is on you don't have the choice.
 
Hi All

I recently moved into a house with a Baxi back boiler and eventually worked out that it is a C plan system.
I originally had issues with hot water, but replacing the cylinder stat has sorted this out.

Todays question however is about replacing my single channel programmer.
I dont need the HW on all the time that the CH is on, so thought it would be better to limit the HW by timer, by replacing single channel with twin.

Is this possible with a C plan system?

yes that is if you have C-plan but chances are you haven't as dcalkwell suggests
so no probably not, you will have to convert to either c,y,or s plan
 
Thanks

How would i tell if gravity or C plan? I was under the impression mine was a C plan as there is a 2 way valve for the HW? The valve is then connected to the cylinder stat.
 
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Thanks

How would i tell if gravity or C plan? I was under the impression mine was a C plan as there is a 2 way valve for the HW? The valve is then connected to the cylinder stat.

Then you do have c-plan and yes you can fit a 2 channel programmer
Hopefully you won't need to do much with the wiring

Matt
 
If you have a 'C' plan all 6 cores of motor valve will be used , ie: white core won't be 'parked up' (auxilary)
 
If you have gravity HW, when you switch CH, HW also goes active on the programmer i.e. you cannot run CH with running HW as well. Also, good chance when you ramp up the boiler thermostat setting, HW will be very hot
 
Have checked wiring of valve and only 3 of the 6 cores being used.
The orange, grey and white are all taped off with insulation tape and just tucked into box.

Guess that means i dont have a true c type system then and my hw is gravity?

What happens come summer when i dont want CH on, will HW heat independantly?

Are there any other ways of making this inefficient system more efficient?

How would i convert to c,s,y plans? And what would advantages and costs be? Is it worth it?

Thanks
 
If it is a C plan, then YES you can use a two channel programmer and have separate HW and CH times. I did this 20 years ago on the system at my previous house.

With any luck, all the wires will go into a large junction box. Take the lid off and check the wires from the motorized valve. If all six wires are used (brown, blue, white, grey, orange and yellow/green) then it is a true C plan and you can install a two channel programmer.

Here's the wiring diagram (click to enlarge, then right click to save a copy)

View media item 73
 
Have checked wiring of valve and only 3 of the 6 cores being used.
The orange, grey and white are all taped off with insulation tape and just tucked into box.
Just seen this.

Seems strange to have a valve in the HW circuit (are you certain of this?) and not make full use of it. All it is doing is opening and closing the connection from boiler to cylinder, Which means that HW will only be heated when CH is 'ON'.

The circuit diagram I've just posted shows how to connect the unused wires.

It would be a good idea to check that, when closed, the valve will not block the path from boiler to the open vent (this is the pipe which hangs over the small tank in the loft). If it would, this could create a dangerous situation.
 
Thanks for the diagram.
The valve is situated right next to hw cylinder and connects ( via junction box) to Stat on tank, hence why I assumed its for HW. Actually I'm sure it's for HW as when I was messing about adjusting cylinder stat, as it clicked on and off the valve was opening/closing.

How will I know about checking if when closed it blocking path? I will have to wait if it involves going into loft as my leg is in plaster!!!

Why oh why can't this be a y plan system, I get those!
 
Hi Picasso

Yes, this is exactly what i have!

Does this mean that i can change the controller to twin channel (and rewire) or would this not work?

What about comments about it being a gravity HW so cant control heating without water being on? Would this still be the case?

Feel like i am very very slowly peicing this all together!
Thanks
 
You can fit a 2 channel programmer and rewire as d hailshams C plan posted earlier this will give independant control of your heating and hot water.
 

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