S Plan with Stove + Controls

[Hants-Spark]

I'm after a bit of advice from you heating engineer experts.

I have wired many boilers previously but never to include a wood burner

I have been asked to wire an S plan heating system, no problem with this.
They have also installed a wood burner with a gravity rad and twin coil cylinder.

They have fitted a N/O valve on the return of the stove, low level and high level pipe stats.

Now this is where I'm struggling to see what they want.

N/O valve to close when boiler is running unless the L/L stat makes and opens said valve.
H/L stat opens Heating valve and runs pump but does not fire the boiler.

I can see how to wire the H/L stat to operate v/v, pump via relay, I can see how to include N/O v/v part but just cant get my head around the L/L stat and opening v/v or even why its required.

Any ideas would be greatly received

 

[Leesparkykent]

I'm after a bit of advice from you heating engineer experts.

I have wired many boilers previously but never to include a wood burner

I have been asked to wire an S plan heating system, no problem with this.
They have also installed a wood burner with a gravity rad and twin coil cylinder.

They have fitted a N/O valve on the return of the stove, low level and high level pipe stats.

Now this is where I'm struggling to see what they want.

N/O valve to close when boiler is running unless the L/L stat makes and opens said valve.
H/L stat opens Heating valve and runs pump but does not fire the boiler.

I can see how to wire the H/L stat to operate v/v, pump via relay, I can see how to include N/O v/v part but just cant get my head around the L/L stat and opening v/v or even why its required.

Any ideas would be greatly received

This may be of some help. Page 11,12 and 13 on post below...for some reason wouldn't let me edit and post link here.

 

[Leesparkykent]

http://shop.euroheat.co.uk/ImgShare...Boiler_Management_System_Centre_1_Low_Res.pdf

 

[Hants-Spark]

Thanks for this, much appreciated.
I'll have a good look through tomorrow and see if I can get my head around it. I'm sure it's fairly simple once I fully understand what they are trying to achieve.

 

[aesmith]

I can see how to wire the H/L stat to operate v/v, pump via relay, I can see how to include N/O v/v part but just cant get my head around the L/L stat and opening v/v or even why its required.

Any ideas would be greatly received

A stat on the return to a solid fuel boiler normally operates to inhibit the heating pump if the return temp is too low, to protect the boiler (gravity circuit would continue to flow, so the valve must be open in this state).

In your case you want an additional interlock - close that valve if the boiler's running and the stove's not lit (otherwise you circulate heated water through the stove). Can you map out all the different states, and see how each valve should operate in each state? Then the challenge is how to make the various control inputs and stats give that end result. I can't quite see how you can get the correct behaviour for the N/O valve just from the one thermostat.

The solid fuel and gravity circuit also needs to be safe if the power's off.

 

[Hants-Spark]

Thank you both for your replies, I've done a drawing which I'm hoping is correct although when I scan it, it saves as a PDF and cant seem to load it onto here.

Anyway what I've come up with is, a standard S plan through a relay on the N/C terms, a perm feed to the H/L stat then returning to fire the coil of the relay, the N/O contacts then operate the Heating valve and pump thus dispersing the heat around the circuit.
The L/L stat comes off the N/O contacts then onto the stove valve, thus closing the valve and preventing cold water through the stove when the boiler is running.


Hope I've explained it OK, any questions or comments feel free.

 

[Leesparkykent]

Thank you both for your replies, I've done a drawing which I'm hoping is correct although when I scan it, it saves as a PDF and cant seem to load it onto here.

Anyway what I've come up with is, a standard S plan through a relay on the N/C terms, a perm feed to the H/L stat then returning to fire the coil of the relay, the N/O contacts then operate the Heating valve and pump thus dispersing the heat around the circuit.
The L/L stat comes off the N/O contacts then onto the stove valve, thus closing the valve and preventing cold water through the stove when the boiler is running.


Hope I've explained it OK, any questions or comments feel free.

This could come in handy. http://www.gledhill.net/pdf/torrent range issue 2.pdf

 

[aesmith]

On that drawing, which is the stove return pipe stat, and where does V3 fit in the pipework?

 

[Leesparkykent]

On that drawing, which is the stove return pipe stat, and where does V3 fit in the pipework?

here's the pipework/component layout. Obviously the solar thermal can be ignored.

 

[Leesparkykent]

This is for a gledhill thermal store but the OP could adjust it to his requirements but good as a reference to work off.