Self Build Advice Please - consumer units, sockets & switches...

[janner43]

Hi all,

We are doing a self build 2 bed bungalow in Devon which is going to be very highly insulated with u-values of..
Floor 0.15
Walls 0.14
Ceiling 0.11

With an air tightness factor of 0.8
MVHR with 89% efficiency

* Our other design spec includes no central heating system (not required with the previous specs), we'll just add a panel heater to act as a top up for the stored heat within the home when required. The MVHR should do the rest.

* An "experiment" with no central hot water - just local instantaneous water heaters (3 @ 12kw) where required. Half the plumbing, no dead leg of water, no waste hot water stored. We are not having a bath, so an instantaneous electric shower (9.5kw)

* We are having a 3.7kw solar array. The whole concept is based on the PassivHaus model with a couple of tweaks.

I don't really want to debate the design concepts - feel free to comment if you like, though .
The whole idea has been predicated on thinking differently about the designs when it comes to the heating and water heating together with an avoidance of the connection costs, plumbing, boiler purchase, boiler servicing costs associated with a gas connection (which is available).

We have a great, fully qualified sparky on the project who grew up with our son & is a good guy. I know he'll give us good advice, but I would appreciate several points of view on this please. He is kindly not supplying materials & is letting me source those to save some money. He is also arranging for a pal with the MCS ticket to commission the solar array at mates rates.

That's the background, now to the questions...

1) Consumer Unit...
I wondered if it would be a good idea to have two consumer units...
One for the heavy items - three 12kw water heaters and one 9.5kw shower
One for everything else

Or just get one large unit?

Would there be an issue with the solar array connectivity if we had two consumer units?

I like the idea of splitting as many of the circuits as possible, so what sort of config would you design if this was your build?

2) What brands are the best value for money - I'm familiar (Dad was an electrician for decades, started his trade in the 1950s) with MK, Wylex - but are they as good now as they were or are other names just as good?

3) Any recommendation on which make of sockets & switches to get?

4) Any recommendations as to the cheapest place to buy the gear from please? I already have a Trade Account at Travis Perkins (and Trade Point - don't laugh, it might be handy... )

I hope I have given you enough information & thanks in advance for taking the time to read this and for any answers / opinions / recommends you might be willing to give.

Cheers all.

 

[sean_ork]

How on earth should I know? You'd need the flow rate at the point of connection to find out what it will be out of the tap!
From experience the boiling water is not noticeably slower than the regular hot from a tap.

Again how the hell should I know the average volume of a kitchen sink?

I'm only asking why such a large amount of power is necessary to achieve the same result as can be achieve with much less power?

Post a link please, I'll find its flow rate - there's no point getting excited over it if its flow rate is 2 dribbles a fortnight.

 

[sean_ork]

I thought the whole point of this was energy efficiency?
Using a few sinks worth of dishes to cook a meal is not very energy efficient when meals can be cooked with far fewer dishes!

Maybe some folks want a meal that doesn't just consist of toast and beans

 

[davesparks]

Post a link please, I'll find its flow rate - there's no point getting excited over it if its flow rate is 2 dribbles a fortnight.

Quooker is the best known one, but there are other brands out there.

 

[davesparks]

Maybe some folks want a meal that doesn't just consist of toast and beans

??? That's just daft, you can cook a while roast dinner with just a few pots and pans if you know what you are doing.

 

[sean_ork]

Quooker is the best known one, but there are other brands out there.

I suspected you'd say that - you do know there's a small tank hidden away feeding it ? The only advantage of these £1200 taps over the £145 versions is boiling water and a very fancy tap.

3kW just isnt enough to heat water instantaneously for the flow rate required

http://www.quooker.co.uk/enuk

 

[sean_ork]

??? That's just daft, you can cook a while roast dinner with just a few pots and pans if you know what you are doing.

OK let's assume you can do what no one I've ever known has been able to do ........

So what about the 2,4 or 6 folks who sit down to scoff that roast - will they be using any plates, knives, forks, spoons, then there's pudding, that's maybe 6 more bowls and spoons, then there's a cuppa afterwards, then the cheeses and more drinkies ... that's a good few sinks of washing up, average domestic sink capacity of say 25 litres ?

rough calculation - 10 litres of water, say its incoming at 10 degrees, 90 degrees rise required - 3kW element - that's nearer to 20 minutes to raise that volume to near boiling

 

[Leesparkykent]

Why not just have a unvented cylinder with an immersion or even twin immersion? and you could run the shower off it. Small solar thermal setup on the roof to keep it topped up throughout the day with something like the solar iboost so when the pv is producing more than what's being used it also heats the hot water.

 

[davesparks]

OK let's assume you can do what no one I've ever known has been able to do ........

So what about the 2,4 or 6 folks who sit down to scoff that roast - will they be using any plates, knives, forks, spoons, then there's pudding, that's maybe 6 more bowls and spoons, then there's a cuppa afterwards, then the cheeses and more drinkies ... that's a good few sinks of washing up, average domestic sink capacity of say 25 litres ?

rough calculation - 10 litres of water, say its incoming at 10 degrees, 90 degrees rise required - 3kW element - that's nearer to 20 minutes to raise that volume to near boiling

You do your washing up in boiling water?

 

[sean_ork]

You do your washing up in boiling water?

No, but that's an argument against having a tap that produces boiling water

 

[sean_ork]

Why not just have a unvented cylinder with an immersion or even twin immersion? and you could run the shower off it. Small solar thermal setup on the roof to keep it topped up throughout the day with something like the solar iboost so when the pv is producing more than what's being used it also heats the hot water.

Great, until the sun doesn't shine - and then you've got heat loss from the cylinder and the dead legs - which most folks don't seem to mind wasting their money on living in their conventional energy inefficient home, but that's not what the OP wants to build.

 

[davesparks]

Great, until the sun doesn't shine - and then you've got heat loss from the cylinder and the dead legs - which most folks don't seem to mind wasting their money on living in their conventional energy inefficient home, but that's not what the OP wants to build.

Solar hot water setups are surprisingly good even with minimal available sunlight.
With some careful thought as to the layout you could get the dead legs to be fairly short. And a thermal store rather than a conventional cylinder would presumably help too? (they must have come up with something better than the gledhill heaps of junk by now)

I don't think it's so much a case of not minding about living in inefficient homes, but more a case of not knowing and not being able to do much about it if they did.

 

[Leesparkykent]

Great, until the sun doesn't shine - and then you've got heat loss from the cylinder and the dead legs - which most folks don't seem to mind wasting their money on living in their conventional energy inefficient home, but that's not what the OP wants to build.

A well insulated cylinder/thermal store in a well insulated house the the loss of heat is going to be minimal surely? Same applies to the dead legs...pre insulated pipe and legs as short as possible. Solar thermal works well even on the not very best of days, you would be surprised.

 

[janner43]

OK - someone said I had lost interest in the thread. Nope. I'm just not willing to debate the often ill informed comments that have been posted along with the insightful ones.

Only Sean and spinlondon apparently have any real experience of this type of build. Other than the eminently sensible electrical design advice that has been given which I have already said is making me seriously consider changing the rating of the water heaters, 80% of the posts are just argumentative and "you don't want to do it like that". I said I didn't want to debate the design scenario, but there appears to be a lot of interest (or maybe not).

I understand the reasons why folks don't know or haven't considered alternative build or design scenarios. I also understand the uselessness of many of the alternatives that are out there which are only really useful in two cases.
1) Where the environment is harsh and requires it
2) Where the technologies are being fitted as part of a refurb rather than a new build.

Where we live the average winter temperature doesn't fall below 3.7° - Plymouth, England Climate Plymouth, England Temperatures Plymouth, England Weather Averages
As a result, high levels of insulation and air tightness coupled with an efficient MVHR should mean no heating is required over that generated naturally within the home.

These things are calculated properly and scientifically and do not require opinion. If top up heating does prove a requirement, I think you'd agree that adding a 1.5kw panel heater somewhere shouldn't prove too challenging!!!

As it is my home, my opinion on the quantity and frequency of hot water that will be required is such that showering and hand washing are all that should take place. We wash our clothes in a washing machine. We wash our dishes in a dishwasher. What you might do is a matter for you.

We are trying to build a 21st century home - not an 19th century one. We are using state of the art knowledge and techniques. Only one other home has been built in the UK to date using the build method we are using. That was the proof of concept in Scotland. Ours will be the first commercially built home after that.

I have also effectively been called a liar - the first time it was reasonable and put in a polite way and I understood and answered it. After that it is just offensive.

In short, while you guys unquestionably know more about electrical science than I. I am not going to take lessons in the overall design concept or in day to day living paradigms from you, thanks very much.

Finally, again my genuine appreciation to the posters who have helped with their constructive suggestions and observations.

 

[Octopus]

OK - someone said I had lost interest in the thread. Nope. I'm just not willing to debate the often ill informed comments that have been posted along with the insightful ones.

Only Sean and spinlondon apparently have any real experience of this type of build. Other than the eminently sensible electrical design advice that has been given which I have already said is making me seriously consider changing the rating of the water heaters, 80% of the posts are just argumentative and "you don't want to do it like that". I said I didn't want to debate the design scenario, but there appears to be a lot of interest (or maybe not).

I understand the reasons why folks don't know or haven't considered alternative build or design scenarios. I also understand the uselessness of many of the alternatives that are out there which are only really useful in two cases.
1) Where the environment is harsh and requires it
2) Where the technologies are being fitted as part of a refurb rather than a new build.

Where we live the average winter temperature doesn't fall below 3.7° - Plymouth, England Climate Plymouth, England Temperatures Plymouth, England Weather Averages
As a result, high levels of insulation and air tightness coupled with an efficient MVHR should mean no heating is required over that generated naturally within the home.

These things are calculated properly and scientifically and do not require opinion. If top up heating does prove a requirement, I think you'd agree that adding a 1.5kw panel heater somewhere shouldn't prove too challenging!!!

As it is my home, my opinion on the quantity and frequency of hot water that will be required is such that showering and hand washing are all that should take place. We wash our clothes in a washing machine. We wash our dishes in a dishwasher. What you might do is a matter for you.

We are trying to build a 21st century home - not an 19th century one. We are using state of the art knowledge and techniques. Only one other home has been built in the UK to date using the build method we are using. That was the proof of concept in Scotland. Ours will be the first commercially built home after that.

I have also effectively been called a liar - the first time it was reasonable and put in a polite way and I understood and answered it. After that it is just offensive.

In short, while you guys unquestionably know more about electrical science than I. I am not going to take lessons in the overall design concept or in day to day living paradigms from you, thanks very much.

Finally, again my genuine appreciation to the posters who have helped with their constructive suggestions and observations.

Probably because you did little of nothing to persuade the masses that you actually have a sparky involved.......

 

[janner43]

Probably because you did little of nothing to persuade the masses that you actually have a sparky involved.......

Look, I do understand why you and others may be dubious - but then again I have stated that there is an electrician and given you all sufficient background to perhaps trust my word on the matter. I don't have the time or inclination to attempt to convince people who are not going to be convinced in any case.

Neither do I have the time or inclination to, as someone put it "argue with an idiot as they will drag you down to their level and beat you with experience".

Neither am I going to debate further than this reply my personal integrity. The facts I have posted in the OP are true, the whole truth and nothing but the truth.