Potterton Miniminder - replacement control

[DaveSmith1972]

Hi

I have Potterton Miniminder controller that I want to replace to enable separate timing control over both HW and CH.

It is linked to a Potterton boiler, not sure of model unfortunately but would hazard a guess that it is 20 yrs old at least.

I have been recommended a Siemens RBW29 controller and it bsically does what the miniminder does but will not control the CH and HW separately as I would like to.

The wiring in the back plate is missing no. 1 & 2 for the HW and CH off.

My question: is it possible to get someone (no chance of me attempting it) to wire in 1 & 2? Or is that simply not possible with current system?

Alternatively is there another controller that will work with current set up.

Any help would be much appreciated.

Thanks

 

[Agile]

Almost all modern programmers will do what you need.

BUT it all depends on how your system is configured. It may well need considerable improvements!

Of course you should have asked the engineer about it at the last annual boiler service.

Tony

 

[stem]

Hi Dave, and welcome to the forum.

The Potterton Mini Minder is actually a Landis and Gyr unit re-badged, and it already has the facilities for separate control of the heating and hot water. If you find that when you operate the slider for the central heating, the hot water one is pulled along with it, that would suggest that the system cannot handle additional control functions and the programmer has been set accordingly. This facility can be removed by turning a selector knob on the back of the Mini Minder, this will allow the sliders to operate independently, but it won't change the way the system works if it is restricted by the plumbing.

With many old systems, to have the hot water 'on' in the summer, only the boiler is turned on, and the hot water cylinder heated by gravity circulation. Then, in the winter, the central heating switches on the pump and circulates the water around the radiators. But in order to do this, the hot water also needs to be 'on' to operate the boiler.

With this system, the only two choices of operation are:

1) Hot water only, or
2) Hot water and central heating.

If this is the system you have, regardless of the control facilities the restrictions of the existing plumbing will mean that you can only have the above 2 options.

On the other hand, if you have motorised valves controlling flow to hot water and central heating

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• stem
• 26 Mar 2010
• 6

...and thermostats for heating

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• stem
• 2 Feb 2010
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...and hot water

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• stem
• 21 Dec 2010
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You will be able to have fully independent control.

 

[DaveSmith1972]

Hi Stem

Thanks for the response, at the moment using the potterton I can have both on independently of the other by simply moving the manual override switch.

However with only one timing dial they only operate together. Now it is just me I don't want the water on as long as I simply don't need it but would like the CH on a bit longer.

The Siemens I tried works and turns it all on but wont allow separate control of the timings.

I have two two port values for heating and water and thermostat etc

Didn't know if this was something to do with the "missing" wiring or simply something the system cant handle.

Thanks

Dave

 

[stem]

It sounds like you have the components required, and that you just need to change the programmer.

It's easy to test that all the required wiring is in place. Turn 'off' the heating and the hot water at the programmer sliders, and set the cylinder thermostat and room thermostat to their maximum settings.

Now just slide the central heating control to 'on' does just the central heating operate?

Now try it the other way around. Does just the hot water operate?

If the answer to both is yes, and it sounds as if it will be, then you just need to change your programmer.