Immersion heater

[marvin9876]

Hi all and happy new year to everyone

Our boiler packed in last week and the electrician who came to fix it replaced a motorised valve and all is now ok. He pointed out to me that the immersion element on our MegaFlow has never been wired and even though the boiler was not working we could have still heated water if the element had been wired in the first place.

I have asked him to rectify this. The boiler is in a utility room with a concrete floor and a flat roof, so getting a wire from the cu to here will be very dificult. The electrician has said that that he can spur from a socket and connect the element to a switch fuse. Is this right? i thought that imersions have to be on a dedicated circuit. The plate on the element cover says 3KW 240 volts 50 Hz. A long time since i did tech at school but i take it that this would be 12.5 amps, so is he correct?

Any advice would be greatly appreciated.

 

[ricicle]

If there is no alternative then connection to the socket is fine as long as it is installed correctly (eg not a spur off a spur)
I would then only use the heater as a last resort when your system packs up as it has recently.
Connection of loads of this nature to socket circuits is considered bad practice as the load is usually on for some considerable time and as such reduces the capacity of the circuit.

 

[ColJack]

on site guide says it has to be on it's own circuit if it's more than 15 litres...

 

[marvin9876]

Thanks for quick response, so this would be acceptable until a dedicated circuit was installed? He will be spurring from kitchen ring.

 

[marvin9876]

Its way more than 15 litres coljack. Is riccle advice incorrect? just want it done correctly/safely.

 

[ColJack]

does your kitchen have 2 rings? one for general use and one for appliances?

if not then no..

the kitchen ring is the most heavily loaded one in the house already..

washing machine, friege, kettle, toaster, dryer, dishwasher, single ovens ( if not on their own cct. ) george forman grill, deep fat fryer etc...

 

[Spark123]

It is considered bad practice to put an item such as an immersion heater on a ring circuit, it is a heavy load and will be on for quite some time. It is better on its own circuit.

 

[ricicle]

Now I know it is on the same circuit as the kitchen appliances then I will say no it is not ideal, although it is a back up heater.Trouble with doing it until a dedicated circuit is installed is things tend to get left as they are.

 

[kevnurse]

True, but its a back up in case of a gas boiler failure, which shouldn't be a regular event and the motivation to get the boiler fixed (for central heating and cheaper hot water) will reduce any tendency for the user to stay on the immersion heater. What I would do is buy a double pole timed booster switch which means that the heater will go off automatically after say 30 minutes.

 

[Lectrician]

How close is the CU to the kitchen?

I know it aint the prefered method, but kick board plinths spring to mind...

 

[marvin9876]

Cu is on the other side of the house with two rooms and a hallway between it and the utility. All concrete floors. Starting to think that the spark will have to somehow come from the cu to outside and somehow cable along the outside wall and come back into the utility as this is the shortest route. Could this be done in P.V.C conduit? or armoured cabled?

Mate popped in tonight and he suggested wiring a metre of flex to the element terminals with a plug top on the end that could be plugged into the nearest socket if the boiler packs in again.... this sounds iffy?

I really do appreciate all your efforts, thanks again.

 

[ColJack]

is your shower a mixer type or electric?

if it's electric then you don't need a tank full of hot water.. use a kettle to wash up and the shower for a bowl of water to wash hands..

the plug idea is do-able, but it would be best run through an immersion timer that only turns it on for 15-20 mins every hour..

 

[kevnurse]

Cu is on the other side of the house with two rooms and a hallway between it and the utility. All concrete floors. Starting to think that the spark will have to somehow come from the cu to outside and somehow cable along the outside wall and come back into the utility as this is the shortest route. Could this be done in P.V.C conduit? or armoured cabled?

The most efficient route for a permanent radial to the DHW tank is up through the void between the ground floor ceiling and the upstairs floor. You don't have laminate upstairs do you?

 

[ColJack]

The boiler is in a utility room with a concrete floor and a flat roof

not as easy as all that..

 

[EdSet100]

It shouldn't be too difficult to get below an external flat roof. Take the cable to the end of the void where it meets the wall supporting the flat roof and go straight down inside the wall to an appropriate point to go through the wall to the utility room. upvc trunking can be used for the route up and down to the void.