changover contactor for auto-supply change on boiler

jdownie · 17 Oct 2009

Hi All,

I've got an older peak/off peak setup in my house - 2 meters and 2 consumer units. The off peak supply is switched on via a radio tele switch. Currently i have a 9Kw electric boiler running from the off peak supply. I want to have the supplies auto change over between the peak and off peak supplies - so the boiler is available 24 hrs a day.

The current setup looks like this:
View media item 15807
Would this best be achieved with a 4 pole 40A changeover contactor to achieve something like this:
View media item 15808

Or is there a simpler setup that I'm missing - and if not - does anyone know where can i get a 40A changeover contactor?

Everyones input appreciated.

ricicle · 17 Oct 2009

Just use a manual changeover switch (usually used for generator set-ups) but don't switch it on-load (ie fit another isolator for the boiler if not already one fitted)

jdownie · 17 Oct 2009

thanks for the reply ricicle - can you suggest a way to have achieve an auto change over? The boiler/CU's are in a small room under the main house and getting to the controls would be a drag (necessitating going outside). I'm not lazy - but work away from home sometimes and my wife will tune me out if she has to go outside to flip a switch...

ricicle · 17 Oct 2009

Why do you need the boiler 24 hrs a day ?

jdownie · 17 Oct 2009

central heating during winter. The CH can't come on during the day at the moment.

ricicle · 17 Oct 2009

Basically - 2 mechanically interlocked contactors (suitably rated). Coil for peak contactor fed from peak supply but via normally closed contact of off-peak contactor. Off-peak contactor coil fed from off-peak supply.
When peak is on then so is contactor. When off-peak comes on so does off-peak contactor but peak contactor is held off by aux. contact.
You could have normally closed contact of peak contactor holding off off-peak as well for bolt and braces. Also master switch to keep both contactors off (holiday etc)

Lectrician · 17 Oct 2009

An electric boiler should be on the peak supply so it is available when ever required (as a gas boiler would be).

Econ 7 and econ 10 type tarrifs provide cheap electric to all circuits during the off peak hours. The teleswitch is good for storage rads and stored water.

Electric boilers are best suited to econ10 tarrifs to provide cheaper lecky when required. Storage heaters are best suited to econ7.

jdownie · 17 Oct 2009

ricycle - thanks alot for your help. You've described just what i'm after. I've searched around a bit and found a Hager 63A ES470 unit that is 4 pole 2NO - 2NC - this appears to be what you've described in a single unit.

Lectrician - cheers for the clarification - i've inherited this system and i have to stick with it until i can afford an oil based system or an underground propane tank, or the gas co. decide to extend the main

nozspark · 17 Oct 2009

I think you'd be better off asking our supplier for a tariff change.. hopefully they will then give you a dual tariff meter rather than 2 seperate ones.

This would mean that both cu's get the cheaper rate, but only the peak rate one gets the peak rate.. then connect your electric boiler to the peak rate cu.

Lectrician · 18 Oct 2009

I concur - It would be cheaper than playing around with changeover contacts, and would be a better solution.

If you change tarrif, the meter alterations are free of charge.

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changover contactor for auto-supply change on boiler

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