# Boiler wiring problem



## McClary’s Electrical (Feb 21, 2009)

KevA said:


> Hi,
> I have been fault finding on a Heatrae Sadia Electromax combined electric boiler and domestic hot water supply store. The appliance has a 45A circuit for the boiler and 16A circuits for the immersion heaters, one circuit is for off-peak (e.g. Economy 7 or 10) and one for normal '24-hour' supply. It appears that the MCB (owner a bit vague) for one circuit has been tripping and a double pole isolating switch shows signs of overheating plus the control circuit board has been damaged. A engineer for the manufacture has been previously called out and said an additional circuit is needed (no report or paperwork to refer to as yet to find out what they mean).
> 
> The connection block in the appliance housing has 2 sets of terminals for the 16A circuits and one set for the 45A circuit. When I had a look at the block the 45A circuit is connected OK and there is one 16A circuit connected to the 24-hour supply terminals, 2 links have been added from
> ...


 
I don't know the model. But it sounds like you need a circuit to each set of terminals. 6kw @240 is 25 amps. They missed a circuit, installed jumers, and have overheating issues because of it.


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## frank (Feb 6, 2007)

KevA

You need 2 circuits. One for Boost and one for Economy use. But before you do anything make good to all damage.

Frank


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## chrisb271 (Jul 6, 2007)

Hi KevA

Frank is right about requiring an additional cicuit,I have installed these heatrae boilers before and always have wired two 16Amp circuits along with the 45 Amp one ( one 16 Amp for peak use off the general distribution board and one from the off peak DB )

Both immersion heaters in the boiler can and DO operate together thus drawing over 32Amp on your linked out terminals,they say ignorance is bliss but linking both elements on one supply is just nuts.

Chris


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