megaflow connections

[has]

Today, had to connect up tank stat and immersion on a heatrae sadia megaflow. Both connections are in the same box on the side of the megaflow. Wondered if anyone had similar problem before as both circuits are in the same terminal housing. Just thinking along the lines of plumber/gas fitter coming to fix a problem opening the box and thinking it was isolated due the boiler supply being turned off.
Have left imersion disconnected for time being as new build but would welcome any feedback. The only solution to me is to label the cover apropriately.

 

[plugwash]

lablelling it seems the best bet. something like

WARNING isolate both central heating and immersion supplies before removing this cover

would seem reasonable.

 

[Big_Spark]

Has, If these are the same Megaflows as I have been connecting up recently in Hackney, then I can help you.

The TOP Immersion/Stat pair is the BOOST whilst the bottom Immersion/Stat pair is the OFF PEAK.

You should have a controller that has a common feed, unless you have true economy 7, a single 13A spur will suffice as both immersions cannot be turned on simultaneously.

If you have the correct controller, these are Heatrae Sadia Units, then the connection are simple.

Terminal 1 = Live Feed In
Terminal 2 = Neutral Feen In
Terminal 3 = Common Immersion Neutrals
Terminal 4 = Live BOOST Feed to Immersion (top unit)
Terminal 5 = Live OFF PEAK Feed to Immersion (Bottom Unit)

Then on one side there is a pair of EARTH terminals.

If you need me too I can find out the actual Controller Model Number tomorrow.

Should any maintenance be required on the Megaflow, then simply turning off the common Spur will Isolate both Immersion Elements.

 

[has]

FWL, thanks for that but this ones appears different. It has terminals 1,2 and 3 for the tank stat that connect to the valve, than in the same housing is the stat of the imersion labeled terminals A and B. Have had it confirmed by Heatrae as such. I just feel its bad design and am hoping for some info before I reply to them as we have another 9 to install.

 

[Big_Spark]

The stat for the Valve should be Live - Neutral and then a Switched output, and that would make the 1,2,3 connections you see.

The other connection will be a Switched live across the stat for the Immersion, I am assuming the Neutral must be common to both units.

 

[has]

Thanks but i think we may be getting our wires crossed here, I know how to connect it all, the concern is having two seperate circuits in one housing. Theres no warning labels etc, so when the plumber comes to say for example change the tank stat he wont be expecting live wires once he has isolated the boiler supply.

 

[HDRW]

FWL:
I think I can see a misunderstanding here! You are describing a twin immersion heater unit, I believe Has is talking about one that has indirect heating by a boiler, and one immersion heater!

If so, the "stat" he is talking about is the one that controls the boiler, not the immersion heater. Hence under the one cover there is the live that's from the boiler, and another live to power the immersion, which is why he is concerned that two isolations are required to render it safe to work.

That's what I reckon, but then I have been completely wrong before!

Cheers,

Howard

 

[has]

HDRW
Thanks for that you are correct. Wasn't so much a what wires go where as more an isolation issue.

 

[Driller]

Fitted one last week.

I did exactly the same as plug suggests, even the wording is almost the same.

Also put a label in the cu warning the same.

 

[kai]

Just put two 13amp fuse-connection units side by side on the wall, one for the boiler circuit, and one for the Immersion Heater, It will be obvious that the unit has two sources of supply that need isolating. (because of the 2 flexes between the FCU and megaflow). Label it Accordingly.

Is the Earth Bonding of the megaflow unit Up to Standard?

 

[has]

Kai,
sorry for delay but been away, can,t really put isolation spur for central heating near the tank as in loft and boiler is downstairs. Corgi guys need isolator close to boiler. Bonding not a problem as new build all plastic pipe, lovely stuff.