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DHW Immersion when ASHP is Broken


Cbuzz

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Hoping someone can help.

 

Waiting for a Dimplex engineer to come and diagnose a problem in my LA-6 ASHP. There is no power coming from the unit (A PCB may be fried but thats another story)

 

The problem is that I think the DHW unvented tank immersion is powered by the ASHP (or not powered in this case) so currently I have no heating OR hot water.

 

Is this normal setup and is there anything I can do temporarily to get hot water?

 

thanks in advance

 

Buzz

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The immersion on mine is cabled through the ASHP controls, because that is what controls the disinfection cycle. 

 

I don't see why you couldn't temporarily wire the immersion straight to the wall, but I'd personally ask the installer or an electrician first.

Edited by George
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Thank you all for the help,

 

I assumed that the idea behind the immersion was for a separate source of power in case of emergency. The wiring diagram in the ASHP manual does show a 3 core cable going to the immersion.

 

the cable going from the immersion in the cupboard does go to a switch on the wall but there doesn’t seem to be any power coming from it at all (my basis of this is the voltage testing pen hovering over it and staying green) 

 

There is no ‘immersion’ RCD switch on the Consumer Unit, just one for central heating and one for ASHP. So it’s definitely not on its own circuit.

 

I have attached some photos that I hope will help.

 

thanks

 

 

 

 

 

 

 

B11A594B-766C-4D33-9261-5780C881B9C2.thumb.jpeg.8a86d8b70bc0fb2f579cb746070896b6.jpeg 

8858A140-141E-4983-B4B3-9AE6FF7509DD.jpeg

ASHP Immersion Diagram.jpg

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Sorry that tank picture didn’t actually show the immersion cable leaving the tank, it just showed the sensor ones above it

 

This cable in this picture goes to a fused spur on the wall which doesn’t appear live, which I assume is because the ASHP is dead.

CCA6E05C-082E-4752-B595-39E21E4AA082.jpeg

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22 minutes ago, George said:

I don't see why you couldn't temporarily wire the immersion straight to the wall

If you mean into a wall socket, it is because it will weld the plug to the socket and crack the plastic.

13Amp wall sockets are only rated for a 10Amp continuous load.

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4 minutes ago, TonyT said:

Zoothorn Technical Services, is in Wales somewhere



 

only kidding.

Just checking in case it saves a fallout.

All MCBs/rcbos are in the on position?

rotary isolator on?

 

Sadly I have checked all of those. Thought I had followed the thermostat installation instructions to the letter but inadvertently caused a big 'bang' and after setting all the MCBs and RCBOS back to the on position and putting the original thermostat back on then sadly there is no power. Nothing to the controller, thermostats, or anything that the ASHP supplies. There is power going to it but nothing coming from it so I suspect I've blown a PCB in there. Such a stupid mistake and after this is all fixed by a pro I wont be touching it again. Expensive lesson to learn I think

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17 minutes ago, SteamyTea said:

If you mean into a wall socket, it is because it will weld the plug to the socket and crack the plastic.

13Amp wall sockets are only rated for a 10Amp continuous load.

 

No I meant to the isolation switch for the board - as that ultimately is what powers the immersion so must be adequately rated.

 

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Many heat pumps (mine included) want the immersion heater wired through the HP.  This is so it can turn on the immersion periodically for anti legionairs heating.

 

In my case this is achieved by a contactor in a box, and I wired a local override switch should I wish to turn the immersion on at any other time.  I also connected my solar PV diverter the same way.

 

Many of us have concluded that with treated mains water and an unvented cylinder there is no legionairs risk so we have disabled that function.  If you made the same conclusion you could just rewire your immersion heater in the normal manner with a manual switch.

 

In the short term you could just wire the immersion heater to a flex and a plug to get some hot water until you get the ASHP fixed.

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16 minutes ago, TonyT said:

You should have a second immersion at the top behind that green access panel.

 

don’t know if you are competent to wire this up ?

There is an immersion yes but I wasn't sure if this was a separate part of the tank and not to be used, not sure why this wasn't wired in by the original installer.

 

 

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Yes I will do that, Can the bottom part continue to be connected to the ASHP and the top connected to a suitably rated wall socket? they wont interfere with each other will they? I suppose I would only use the manual one in emergencies like this.

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1 hour ago, Nickfromwales said:

Just rang my mate, but they’re flat out and not taking new jobs on atm. 

Thank you for trying, appreciate it. I will run a new radial circuit back to the Consumer unit from the Airing Cupboard tomorrow ready for an immersion heater switch but I'll leave the thermostat cabling to the pros in future I think ?

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10 hours ago, Cbuzz said:

Thank you for trying, appreciate it. I will run a new radial circuit back to the Consumer unit from the Airing Cupboard tomorrow ready for an immersion heater switch but I'll leave the thermostat cabling to the pros in future I think ?

Get the new Selco d feed in from the CU, and ask the sparky to make it off to a 16a wall mount socket. Ask him to then make the ASHP > immersion cable off into a second one. Then ask him to connect that immersion to a 16a plug. 
Then, if you have problems, you just unplug from the ASHP and plug into the new radial feed. 

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