Electrical supply for 9kW Electric flow boiler

[Jack155Q4]

Hi there,
We are looking to buy a new boiler and have an electric one fitted in place of the gas (for various long drawn out reasons )

In the manual of the boiler we are considering it says it requires:
-- Double pole RCD with trip level sensitivity to 30mA
-- Double pole linked switch with minimum contact gap of 3mm between poles.

Will this RCD be suitable for this application:
http://www.qvsdirect.com/80-Amp-30mA-Double-Pole-RCD-pr-25097.html

This is the fuse box etc we have now.

Consumer Unit:
http://cgi.ebay.co.uk/Wylex-Consume...A-Main-Switch-NEW-/290548936427#ht_1956wt_907

There are 2 spare slots.

This is the wiring diagram:

Many thanks for your help,
Jack

 

[EngStudent]

Will this RCD be suitable for this application:
http://www.qvsdirect.com/80-Amp-30mA-Double-Pole-RCD-pr-25097.html

This is the fuse box etc we have now.

Consumer Unit:
http://cgi.ebay.co.uk/Wylex-Consume...A-Main-Switch-NEW-/290548936427#ht_1956wt_907

There are 2 spare slots.

Jack

No. The RCD doesn't have overcurrent protection; what you want is an RCBO, which is an MCB and an RCD combined.

This work is notifiable, etc etc.

 

[Jack155Q4]

Will this RCD be suitable for this application:
http://www.qvsdirect.com/80-Amp-30mA-Double-Pole-RCD-pr-25097.html

This is the fuse box etc we have now.

Consumer Unit:
http://cgi.ebay.co.uk/Wylex-Consume...A-Main-Switch-NEW-/290548936427#ht_1956wt_907

There are 2 spare slots.

Jack

No. The RCD doesn't have overcurrent protection; what you want is an RCBO, which is an MCB and an RCD combined.

This work is notifiable, etc etc.

Many thanks - how do you mean by notifiable? As in - get it done properly?

 

[EFLImpudence]

No. The RCD doesn't have overcurrent protection; what you want is an RCBO, which is an MCB and an RCD combined.

It's also protected by an mcb.

 

[EngStudent]

Many thanks - how do you mean by notifiable? As in - get it done properly?

As in;
Notify Building Control before you start work and after you've finished it. They'll charge you an arm & a leg for this, but at least you'll get to do it yourself.

Or;
Get reccommendations from family/friends for a qualified electrician who is part of one of the self-certification schemes (NICEIC, NAPIT, etc) to come and do it for you. He'll install it, test it, sign the papers and notify Building Control on your behalf (the latter will cost him a fraction of what it'll cost you). If nobody you know can reccommend anyone, get 3 quotes.

For what you want it'll almost certainly be cheaper to contract an electrician to do it.

 

[ban-all-sheds]

Hi there,
We are looking to buy a new boiler and have an electric one fitted in place of the gas (for various long drawn out reasons )

You do know that it'll cost you about 3x as much to run as the gas boiler?

Will this RCD be suitable for this application:
http://www.qvsdirect.com/80-Amp-30mA-Double-Pole-RCD-pr-25097.html[/QUOTE]
No:-

a) It's not the same make as the CU

b) having a single RCD covering all of the circuits is likely to be so inconvenient as to be a contravention of the Wiring Regulations - at best it's extremely bad practice.

There are 2 spare slots.

You're not thinking that the RCD can go in those, are you?

Have you got a spare 40A breaker for it?

Have you worked out what cable size you'll need, given the installation method and allowing for volt-drop?

• http://www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html[/list]
  What about testing the new circuit? http://www.tlc-direct.co.uk/Book/8.1.1.htm
  
  Also, are you aware that this work is notifiable?
  
  
  You need to get an electrician.

 

[EFLImpudence]

Is it just the diagram or have you done away with the Main Switch?

It's not advisable to have the RCD as the main switch as one fault will turn off the entire house.

 

[Jack155Q4]

Is it just the diagram or have you done away with the Main Switch?

It's not advisable to have the RCD as the main switch as one fault will turn off the entire house.

OK thanks all. So, how much can i expect to pay to have this done by an electrician? The boiler sits opposite the CU so no difficult routing of wires etc.

The reason we can't have a gas boiler is because the flat was designed with a Keston boiler with 2x 50mm flue pipes which go in to the plaster board wall and no one can work out where ater - they can not be inspected or adapted to a new (non Keston) boiler. The only option was to route a new flue 5 metres through our bedroom to the outside wall. We did not fancy that and the cost was quite a lot higher. Bit of a unique situation.

 

[EFLImpudence]

You could have a separate Garage/Shower Unit containing RCD and MCB fitted.

£40 for unit, bit for cable plus a day's pay at the most.

 

[Lectrician]

With these boilers it is common to fit a two way CU adajcent the boiler submained from your main CU (notice they recommend airgap), or a seperate sw-fuse.

 

[JohnW2]

Is it just the diagram or have you done away with the Main Switch?

I may be wrong, but I assumed that the diagram came from the MI (or some generic source) and was nothing to do with what the the op had done (or 'done away with') or was proposing. In any event, the "DP RCD or DP isolator" on the left of the CU is surely the 'main switch'?

I also wonder at the wisdom of having the MCB for such a high current circuit at the furthest possible position from the main switch/RCD - which is what the diagram appears to be suggesting.

Finally, it would surely be for the manufacturers of the MCB (not of the boiler) to indicate if an adjacent airgap was necessary (which generally they would not say), wouldn't it?

Kind Regards, John.

 

[Jack155Q4]

The diagram came from the install manual here:
http://www.plumbnation.co.uk/site/amptec-c900-9kw-electric-flow-boiler/amptec-installation-guide.pdf

What would be my best option to solve this?
I will phone a few electricians today to get an idea of cost. What should I specifically ask for to get an accurate quote?

Thanks,
Jack

 

[flameport]

The only option was to route a new flue 5 metres through our bedroom to the outside wall.

There is always another option. Moving the boiler to an outside wall for a start - extending pipes will be much easier and cheaper than extending the flue.

If the existing flue is concealed behind plasterboard, then cut a hole in the wall to see where it goes. Replacing a section of plasterboard and redecorating is a couple of days of mess - compared to a lifetime of throwing money away on an electric boiler.

The cost of installation is tiny compared to the thousands of pounds you will throw away on the running costs for an electric boiler.

Try comparing the power output of the old boiler and the new electric one. Guaranteed that the electric one has a significantly lower output, which means it will either be on 24/7, have extreme difficulty in heating your home, or both.

In summary, electric boilers are useless, and installing one to replace a gas boiler is a huge mistake which you will regret every day until you move out.

 

[Jack155Q4]

The only option was to route a new flue 5 metres through our bedroom to the outside wall.

There is always another option. Moving the boiler to an outside wall for a start - extending pipes will be much easier and cheaper than extending the flue.

If the existing flue is concealed behind plasterboard, then cut a hole in the wall to see where it goes. Replacing a section of plasterboard and redecorating is a couple of days of mess - compared to a lifetime of throwing money away on an electric boiler.

The cost of installation is tiny compared to the thousands of pounds you will throw away on the running costs for an electric boiler.

Try comparing the power output of the old boiler and the new electric one. Guaranteed that the electric one has a significantly lower output, which means it will either be on 24/7, have extreme difficulty in heating your home, or both.

In summary, electric boilers are useless, and installing one to replace a gas boiler is a huge mistake which you will regret every day until you move out.

We know - it has all been considered. I have gained a lot of opinions on this situation.
We don't have a great outside wall as such as most of the back of the flat is taken up by windows. We are probably going to move in a year. It may make the place harder to sell but some heating is better than none.

It is primarily for hot water as the heating is all underfloor (the flat is a very small one bedroom place and very well insulated) We don't use the heating much at all (a lot of the time it wasn't working in winter anyway and I can't really say we suffered greatly).

At the moment we have a Keston Celcuis 25 (massively over what the place needed (must have been a cheap job lot when building the flats as apparently it was out of production at this time. which if we can get to run will heat for about 1 hour and that does us for 2 days of hot water.

If I pull away the plaster board I am only going to see next doors wall - we are the middle of 3 flats.

Thank you for your input though.

 

[bernardgreen]

Flameport's comments are very valid.

The cost of running an electric boiler is much greater than the equivalent in gas fuelled heating. Having all electric heating will be a very negative point when you come to sell the flat.

The bedroom cannot be the only room with an outside wall and running pipes to such a room would be much easier than running a concentric flue.

With modern sealed fan driven combustion boilers virtually any room can be used to locate the boiler. ( noise may be problem in a bedroom ). One consideration is the condensate drain pipe which must reach a suitable drain within 3 ( or 5 ) metres.