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Discuss Immersion heater and central heating on same circuit? in the Electrical Forum area at ElectriciansForums.net

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B

BillyH

Would you loop of an existing immersion heater spur for a new central heating spur or, would you run a seperate supply?
 

micknew

Electrician's Arms
Install a single socket and put a plugtops on the immersion heater flex and boiler feed.
That way only one can be used, you don't normally need both on at once anyway.
Gas being cheaper than electricity the immersion is usually only used in an emergency.
 
B

BillyH

I would preferably run a new supply, or feed the boiler from another circuit.
Why would you? You would never use both together as the immersion would be a back up only. Y plan is minimal load any way
 

spinlondon

Forum Mentor
1, I don't like immersion heaters on plug tops.
2, I wouldn't have both methods of water heating on the same circuit, as a fault in one could knock out the other.
3, The immersion heater is quite a large load, and it is recommended that such loads are placed on separate circuits.
 

Andyfm

Regular EF Member
Put them both on a 20 amp radial - immersion fused at 13 amps ( hope i`m not gonna start another row here about running 13 amps through a 13 amp fuse) and CH at 3 amps or 5 amps as required
 

Flyingsparks

Regular EF Member
Strangely enough it seemed to be a common practice to wire an immersion heater from a ring main circuit in the 1960s using a switched spur unit for isolation.

I have seen a quite a few overheated fuse holders over the years !
 
D

Dave 85

Personally I tap Immersion heater circuits quite a bit, cos they never get used anyway. Imm heaters about 12.5 amps and a 2.5 radial can go on a 20amp MCB so not really a prob load wise.
 
B

BillyH

20 dp switch for immersion heater and dp sw fused spur @ 3a on a 2.5 radial would satisfy loading but why would you want to run 2 2.5 radials? Personally i would never run an immersion on a sw fused spur
 
D

Dave 85

I have never seen an Immersion on anything other than a SFS. It is after all a 13 Amp fuse, surely theres a reason that all imm heaters draw almost exactly 13 amps
 
P

PC Electrics

Although many existing immersions have a swFCU. Often on a 15A 3036. I'd leave it as is unless there's a problem, but would install a 20A DP by choice.

99% of domestic ch systems will pull less than 1A - it's the pump that's the large consumer and these are rarely more than 150W. So, CH and immersion on a 16A mcb should present no problems. Both should have DP isolation (remember most FCUs are SP).
 
P

PC Electrics

I have never seen an Immersion on anything other than a SFS. It is after all a 13 Amp fuse, surely theres a reason that all imm heaters draw almost exactly 13 amps
It was usual in the 60s to fit a small square 20A DP sw.
In the villages round our way where there is no gas people tend to use immersions rather than oil for hot water. I've come across many burned out swFCUs. Always replace with 20A DP sw.
 
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