Under Sink Hot Water (IWH) - Connecting to fuse board...

[Wayne Brian Pearsall]

I'm in a house with no Nat Gas, and we have an electric shower.  We use the cylinder on Econ 7 to boil water - but this water is only used to wash up / wash hands after loo (and the kids dont use the hot, b/c it's too hot for them)...

So, I've got a couple of 3700 W (3.7KW) DAFI "under sink" tankless heaters. One for the kitchen, one for the bathroom.

So, connecting it to the consumer unit, I know they need to be on the RCD side, but want to check a few things before doing anything.

They'll have 20A DP switches (the bathroom switch will be outside the bathroom on the wall), and the kitchen one, next to the heater (the heater will be fitted above the sink to existing pipework - which will be cut etc)

Now, It'll be wired with 2.5mm twin & earth...

Where in the consumer unit should I connect this?

Can I spur off the Shower connection?...  I've got a 32a breaker on the kitchen sockets (washer / kettle / microwave / freezer) - can I put the additional into this ring? (directly at the breaker)?....

In the bathroom, I did consider D/c the immersion heater and connecting the IWH instead (do away with the immersion cylinder ETC)...  Any advise on this?... any one got a house without cylinder / boiler that relies only on IWH?

 

[Apache]

Hello and welcome.

I believe fixed heating loads, such as these, need to be on their own circuit, to comply with the regulations. They are 16A each!

Do you have space for additional breakers in your consumer unit? Do you know what your earthing arrangement is? When were the electrics last checked - do you have a certificate to hand with the results on? What other loads are on your system?

Random change of subject - it's VERY important from a hygiene view that children wash their hands properly with warm water. Have you got mixer taps - that way you can get the perfect temperature for safe hand washing. If not then how about a thermostatic valve on the hot water - to top you burning the kids - they are adjustable so you can turn them up as they get older and more sensible.

http://www.rwc.co.uk/products/thermostatic-mixing-valves-tmv

 

[Wayne Brian Pearsall]

I thought that was going to be the answer.  Sadly no space in my CU for additional breakers - and i'll need two...  The elects were last check start 2014.  Earthing arrangements? - we have two massive spikes outside into our ground... (we have overhead powerlines) [if that's what you mean].

Domestic Visual report... is that what you mean?

So the IWH might not of been the best route...  A 2KW tank can be plugged directly into the ring main? (via a RCD)?

---

On the kids washing hands - Don't worry, I make them, but they rush on their own b.c the water is too hot

"For England and Wales, from 1 April 2010, revisions to Part G of the Building Regulations (Hot water supply and systems) include the requirement that baths, subject to building regulations, are fitted with a protective device (i.e. a thermostatic mixing valve) to limit the temperature of hot water. Similar regulations have been in force in Scotland since 2006." - that's actually new to me too  never knew that one...

 

[Davethsparky]

I thought that was going to be the answer.  Sadly no space in my CU for additional breakers - and i'll need two...  The elects were last check start 2014.  Earthing arrangements? - we have two massive spikes outside into our ground... (we have overhead powerlines) [if that's what you mean].

Domestic Visual report... is that what you mean?

So the IWH might not of been the best route...  A 2KW tank can be plugged directly into the ring main? (via a RCD)?

---

On the kids washing hands - Don't worry, I make them, but they rush on their own b.c the water is too hot

"For England and Wales, from 1 April 2010, revisions to Part G of the Building Regulations (Hot water supply and systems) include the requirement that baths, subject to building regulations, are fitted with a protective device (i.e. a thermostatic mixing valve) to limit the temperature of hot water. Similar regulations have been in force in Scotland since 2006." - that's actually new to me too  never knew that one...

Youll need an electrician to fit an additional CU and install the circuits for you. 

A domestic visual report isn't worth the paper it's printed on.

if the water is too hot then turn the temperature set point Of the immersion heater down.

 

[Apache]

if the water is too hot then turn the temperature set point Of the immersion heater down.

Not too low - it will be colder by the evening and risks of things like Legionnaires disease.

I'd rather go for mixer taps or thermostatic valves.

(I have no gas either - just storage heaters and electric immersion)

 

[Wayne Brian Pearsall]

by additional CU, I am taking that a SECOND CU can be added (well third in this case, as we have a second for Storage heaters on night) by a sparky - i assume by just siting it next to the original and putting a feed from the main switch to the RCD  in the second CU?  

(So if all the cables etc are run already, - and heaters plumbed in, it shouldn't take long and cost a fortune?  - I do have a small CU in my shed with two 32A breakers on) - [bought last year as wanted to wire up second shed at some point]

So would anything else be needed... ? or is it looking like just paying a spark for his time?

-- Also: the temp on the Immersion can't really be changed... the other reason for doing this is there is a considerable pipe run from cylinder to kitchen, and it wouldn't be hot enough to wash dishes etc - plus it takes some time (30ish seconds) to flow warm.

The kids are young (6 & 3) so they're sensitive... I can personally have my hand under the hot water without much issue

 

[Wayne Brian Pearsall]

... if this is a job for a spark (as it certainly looks) any guestimates of prices i would be looking to pay...

1) for them to run cables, with all parts already here

2) for them to connect up - with cables run, and parts supplied

 

[Davethsparky]

by additional CU, I am taking that a SECOND CU can be added (well third in this case, as we have a second for Storage heaters on night) by a sparky - i assume by just siting it next to the original and putting a feed from the main switch to the RCD  in the second CU?  

(So if all the cables etc are run already, - and heaters plumbed in, it shouldn't take long and cost a fortune?  - I do have a small CU in my shed with two 32A breakers on) - [bought last year as wanted to wire up second shed at some point]

So would anything else be needed... ? or is it looking like just paying a spark for his time?

No it wouldn't be connected to the main switch of the existing CU, the new CU would have its own permanently live feed. I'm not prepared to explain how this is done in case anyone reading this decides to try it for themselves and dies as a result of working with the live incoming supply to their property.

if the cables are run already then it may take even longer as the electrician will need to inspect them and check that they have been installed as per the regulations and are not damaged and calculate the size of cable required for the circuits.

32A mcbs would not be appropriate for the circuits, and a CU purchased last year may not comply with the new regulation which came in to effect this year.

yes other things are needed, the electrician will check that the rest of the installation satisfies a minimum standard of safety including the correctly sized earth bonding of metal pipework and other parts. 

He will also carry out testing of the new circuits and issue you with an electrical installation certificate and make the legally required notification of the job under part P of the building regulations. 

 

[Davethsparky]

... if this is a job for a spark (as it certainly looks) any guestimates of prices i would be looking to pay...

1) for them to run cables, with all parts already here

2) for them to connect up - with cables run, and parts supplied

In order to estimate the price of the job we would need to know specification of the heaters, length of cable run and incoming supply details in order to calculate the cable size. 

Most at of us will add an additional charge onto our prices if customers want to provide their own materials because they almost always buy lower/poor quality materials which are not so easy to work with or result in extra hassle for us.

Connecting cables run by someone else results in us accepting responsibility for someone else's work which is a massive liability to accept. Obviously it is up to the individual electrician, but personally I would refuse the job unless I know the installation of the cables was carried out by an electrician or if I can fully inspect the cables. 

 

[Wayne Brian Pearsall]

No it wouldn't be connected to the main switch of the existing CU, the new CU would have its own permanently live feed. I'm not prepared to explain how this is done....

So for a job like this (a 10M run - in surface trunking) and a 15m run *(through roof space / floorboards already lifted - and surface trunking down) what would you think I would be looking at? - 

Not too low - it will be colder by the evening and risks of things like Legionnaires disease.

I'd rather go for mixer taps or thermostatic valves.

Thats the issue other, the water isn't as hot when its actually needed either - when you've had that big evening meal, n have all the washing up to do.

 

[steptoe]

what he says,  ^^^^^^^

more or less

 

[Doc Hudson]

Some electrical jobs can be tackled by a reasonably competent DIY in a safe manner. Other work requires a bit more technical expertise in the design, installation and testing to ensure the installation is safe. The work you describe I would not advise being done as a DIY job. You may be able to connect some stuff up to get the heaters apparently working, but in the event of a fault it could be fatal. Electricity can kill a healthy adult in less than half a second. I would hate to think that your children suffer a shock due to the work being not correctly tested and commissioned before use. Standard guidance that has been used for many years: Get three or more local electricians to give you a quote for the work.  It is impossible for someone on the internet to asses the job without seeing it. You mention the existing board has one RCD, this almost certainly does not comply with current wiring regulations and there may be other points that need addressing to ensure the installation is safe with the additional load you want to connect.

Doc H.

 

[ProDave]

If you are removing the hot water tank, then in principle the existing feed to the immersion heater could power the instant water heater in the bathroom.  That only leaves you needing to find one additional circuit.

EDIT re thinking, forget that if it's only an off peak feed to the immersion that you have. But it's usual to have two immersion heaters and a peak rate feed to the top one in case you run out of stored hot water.

I would be concerned at why you have no spares. You obviously have a fairly recent CU to have rcd's in it, and it would be a very poor job to fit a CU that was only just big enough (unless space was really tight) so I wonder if you already have additional circuits that could be better reconfigured.

Best to get a couple of local electricians around to advise a solution and give you an estimate for the cost of the work.

Rather than instant water heaters, I would fit the type that goes under the sink that has a small stored volume of hot water. I have fitted thee before (when the sink was far too far away from the hot tank) and they worked very well with instant hot water and plenty of it. 

I would also seriously look at fitting mixer taps. the hot water must be heated hot, to about 50 degrees to prevent a risk of legionella, so you really want a mixer tap, or a thermal mixing valve to limit the temperature delivered to the taps.

Otherwise do what I did as a kid, when plumbing was in the dark ages, you put the plut in the basin and mix hot and cold until you have a basin full of pleasantly warm water to wash in, rather than was under a running tap.

 

[Doc Hudson]

I would be concerned at why you have no spares. You obviously have a fairly recent CU to have rcd's in it, and it would be a very poor job to fit a CU that was only just big enough (unless space was really tight) so I wonder if you already have additional circuits that could be better reconfigured.

Just because there is an RCD doesn't make it recent, it could still be well over 20+ years old. And it could have been a DIY fit CU as well.

Doc H.

 

[SLIPSHOD & SLAPDASH]

The small consumer unit you have may be no good for the house now as from 1/1/16 the people who write the regulations have decided a plastic unit may spontaneously combust. So, without seeing the job you need a metal board with Rcd main switch and 2, 20 (or 16)A breakers or main switch and 2, 20 (or 16)A Rcbo's. I would fit a 4 way board minimum for future expansion.

 

[Wayne Brian Pearsall]

Hi guys.  

Thanks for comments.   On looking again at cu, there may be one spare slot split into three small spacers.   

The immersion heaters are on a day circuit with timer in the tank Cupboard (found this out when we moved in as the water was coming on in the day on high rate). 

My wife's friend's hubby is a spark, as is brothers wife's Brother,  so will get one of them round to see.  Considering pipe run to upstairs loo isn't too long I may be able to run kitchen n upstairs loo from one heater, n bathroom from other so may have sufficient space.   

The kitchen was rewired in 2003, so I'm assuming the cu is from then. (before we moved in).

I'm guessing replacing the cu will be more than adding an additional cu from meter... 

Considering the kitchen demand a small tank in the kitchen might be better so depending what spark says another unit might get purchased.

Thanks for comments.

 

[Wayne Brian Pearsall]

The small consumer unit you have may be no good for the house now as from 1/1/16 the people who write the regulations have decided a plastic unit may spontaneously combust. So, without seeing the job you need a metal board with Rcd main switch and 2, 20 (or 16)A breakers or main switch and 2, 20 (or 16)A Rcbo's. I would fit a 4 way board minimum for future expansion.

A second 4 way is what I was thinking after comments...  Start with two heaters leaving immersion and if they work out OK, get rid of the tank and possibly add a third heater / split kitchen pipe (this depends on if the pressure after the heater will feed upstairs though)

When spending a few hundred on a project I like to future proof where possible. (spend extra 40 now to save 200 + next year)

 

[Wayne Brian Pearsall]

so I wonder if you already have additional circuits that could be better reconfigured.

Quite possibly can be reconfigured, upstairs had two heaters on the day circuit which have now been d.c. Also have fan heaters in bathrooms which are d.c. So a large load has been removed.  our main draw is the kitchen and hot water. So it's possible the two sockets could be linked.  But ill leave to see what spark Says

 

[ProDave]

Hi guys.  

Thanks for comments.   On looking again at cu, there may be one spare slot split into three small spacers.   

That makes no sense.  A CU can accommodate a fixed number of circuit breakers, there is no such thing as large spaces and small spaces.

Can you post a picture of your consumer unit? you might have to make two more posts on the forum if the restriction of no attachments until you have made 10 posts still stands.

 

[Murdoch]

Best get your Sparks round to quote.....

anything written on here, without seeing the installation is pure speculation.........