Heatrae Sadia Megaflo Thermostat and Economy 7 question

[Glyn81]

I have a Megaflo hot water cylinder in my flat, it has two immersion elements the upper is connected to a boost switch and the lower into a fused wall switch.

Question 1:
I am wondering, having read other Megaflo threads on this forum why the flats in my building do not have Economy 7 meters. We do not have a gas supply so electric water Heating is the only option. Is it usual for an electric only water heater to be connected to non Economy 7 and in effect be switched on all the time maintaining a full cylinder of hot water 24/7 via the thermostat?

It seems like bad planning on the part of the builders but is this in fact normal? Electricity usage seems quite high, so at the very least I'd have expected a timer device instead of just an on/off wall switch.

Question 2:
The lower thermostat I believe has failed, I can only get hot water via the boost button and this provides just enough hot water (the top half of the tank) to have a shower. I've put off sorting it for a while but now want to get it sorted so there is at least the option of running a bath.

I have identified the thermostat as the problem, somehow it has overheated and melted the wire insulation onto the terminals causing it to break the connection. Having stripped back the wires and cleaned up the thermostat terminals I cautiously observed what happened upon reconnection - it did heat water but the thermostat housing became hot to touch (more so than the boost thermostat after a similar time switched on from cold). So I shut it off again and have been using only boost since.

I know people on here will often say get a G3 qualified person in, but I am competent in wiring so once disconnected does the thermostat just pull out, or is there more to it?

Do I need to drain the cylinder first?

I have seen the Cotherm TSE is around £44 so will order online if it's a simple pull out and re-wire job?

Thanks.

 

[Hugh Jaleak]

It may be the lower immersion is on a dedicated circuit, the switching to E7 is done at the meter so no need for a seperate timeswitch at the cylinder.

Thermostat should live in a sleeve, isolate and disconnect the 2 wires and it'll slide out. New stat of appropriate length (probably an 11" immersion, so 7" stat, £8.99 at S/Fix), slide into the sleeve and reconnect wires. Dont need to drain cylinder unless changing entire immersion.

 

[Glyn81]

It may be the lower immersion is on a dedicated circuit, the switching to E7 is done at the meter so no need for a seperate timeswitch at the cylinder.

Thermostat should live in a sleeve, isolate and disconnect the 2 wires and it'll slide out. New stat of appropriate length (probably an 11" immersion, so 7" stat, £8.99 at S/Fix), slide into the sleeve and reconnect wires. Dont need to drain cylinder unless changing entire immersion.

E7
Thanks for the reply, the lower immersion is connected to a fused switch, which is connected to the flat's fusebox. My electricity meter is in a locked basement room along with all the other meters for the 46 flats and it is not an E7 meter. The whole block was only built in 2007 so it just seemed odd to me that the builders/architects/plumbers whoever was responsible for the build deemed it a good idea to have all the immersion heaters in the building running off standard/peak rate electricity 24/7 (although I know not drawing power 24/7) maintaining a full tank of hot water, it must use a whole lot of power.

Replacing thermostat
Good news that I don't have to drain the cylinder and it sounds like a simple removal process. Are you positive I can use a non Cotherm thermostat? All the theads I've read on this matter so far suggest that is the correct item to use, but if it saves £36 with no dissadvantages by buying at Screwfix then I'll do that.

Thanks