immersion wiring help

sajeel · 12 Feb 2015

hi,

currently the immersion is wired to normal supply, however there is second consumer unit connected to economy 7 meter, customer wants to use economy 7 for heating the immersion in evenings, the hot water cylinder is fitted with a single element on the bottom.
So my proposed solution
1) Is to feed a new wire from consumer to economoy7 timer this will then heat tank between 11 - 7 at off peak rate and then can use boost to warm during day if required.
2) Is to feed new wire from consumer unit to change over switch with normal feed and economy7 feed then they can choose between feeds

any other suggestions appreciated

SimonH2 · 12 Feb 2015

sajeel said:
1) Is to feed a new wire from consumer to economoy7 timer this will then heat tank between 11 - 7 at off peak rate and then can use boost to warm during day if required.

I can't follow what you are describing.
One interpretation is how I'd do it :
Take a feed from the economy 7 board, and use it to operate a relay to turn on the IH.
To allow "boost", add a switch in parallel with the relay contacts to override it when on day rate.
For more finesse, use a timer relay - so press button, get (say) 1 hr boost then it reverts to normal. For this, you probably need more than just the one relay if you are to avoid having a "borrowed neutral" involved.

2) Is to feed new wire from consumer unit to change over switch with normal feed and economy7 feed then they can choose between feeds

In which case they'll forget to switch it back and get "a bit of a bill shock"

EFLImpudence · 12 Feb 2015

sajeel said:
1) Is to feed a new wire from consumer to economoy7 timer this will then heat tank between 11 - 7 at off peak rate and then can use boost to warm during day if required.

Yes.

2) Is to feed new wire from consumer unit to change over switch with normal feed and economy7 feed then they can choose between feeds

No. They will forget

OwainDIYer · 12 Feb 2015

sajeel said:
hi,

currently the immersion is wired to normal supply, however there is second consumer unit connected to economy 7 meter, customer wants to use economy 7 for heating the immersion in evenings, the hot water cylinder is fitted with a single element on the bottom.

Usually all the electricity used during the off-peak time is charged at the E7 rate, but the E7 consumer unit is only energsied during the off-peak time.

First clarify the customer understands that 'evening' is not off-peak electricity.

Retain the existing circuit from the normal supply and fit an E7 immersion timer. Set the timer to the correct current time, it will operate the immersion during the off-peak overnight period autimatically, and if the customer needs a boost will supply a peal rate boost without the risk of leaving the immersion on peak rate.

https://www.tlc-direct.co.uk/Products/HOELEC7.html

JohnW2 · 12 Feb 2015

OwainDIYer said:
Usually all the electricity used during the off-peak time is charged at the E7 rate, but the E7 consumer unit is only energsied during the off-peak time.

That's the E7 setup (like the one I have) one commonly sees these days, utilising a dual-tariff meter. However, the OP says that the off-peak CU is fed from a separate "E7 meter". If that's the case, then achieving what the OP wants is obviously not quite as simple as you suggest.

Kind Regards, John

phatboy · 12 Feb 2015

This seems like you are working as an electrician?

Shouldn't an electrician know how E7 works, and the devices available to provide the requires switching without asking here? And probably not refer to cables as 'wires' ?!

JohnW2 · 12 Feb 2015

phatboy said:
This seems like you are working as an electrician? ... Shouldn't an electrician know how E7 works, and the devices available to provide the requires switching without asking here? And probably not refer to cables as 'wires' ?!

One might think that. A peep at the three other threads he's started in this forum over the past 4 years is quite interesting.

Kind Regards, John

sajeel · 12 Feb 2015

Usually all the electricity used during the off-peak time is charged at the E7 rate, but the E7 consumer unit is only energsied during the off-peak time.

First clarify the customer understands that 'evening' is not off-peak electricity.

Retain the existing circuit from the normal supply and fit an E7 immersion timer. Set the timer to the correct current time, it will operate the immersion during the off-peak overnight period autimatically, and if the customer needs a boost will supply a peal rate boost without the risk of leaving the immersion on peak rate.

https://www.tlc-direct.co.uk/Products/HOELEC7.html[/quote]

Usually the e7 meter is wired into main supply and works off peak which in london is around 11 - 7 however this flat appears to have a seperate meter and consumer for the eocmony 7 which was put in place to feed immersion heater but was disconnected.

My plan was to run new feed and install this https://www.tlc-direct.co.uk/Products/SMTRTD7.html
As they only have a single element in hot water cyclinder, the boost and timed load would be linked together and they would use boost to warm up in day if required.
The only issue i have is if the economy 7 meter goes dead in the morning then i will have 2 supplies fed to either a change over switch or a relay that will switch from economy 7 supply to normal supply.

sajeel · 12 Feb 2015

phatboy said:
This seems like you are working as an electrician?

Shouldn't an electrician know how E7 works, and the devices available to provide the requires switching without asking here? And probably not refer to cables as 'wires' ?!

i know how e7 works but this e7 is wired different to usual which is wired together or a dual reading meter is used, in this flat the economy 7 is wired separately as for referring to cables as wires you can sleep on that thought,
I am not asking for a wiring diagram, i was asking for ideas but as usual some people on here just can control themselves

JohnW2 · 12 Feb 2015

sajeel said:
Usually the e7 meter is wired into main supply and works off peak which in london is around 11 - 7 however this flat appears to have a seperate meter and consumer for the eocmony 7 which was put in place to feed immersion heater but was disconnected. My plan was to run new feed and install this https://www.tlc-direct.co.uk/Products/SMTRTD7.html
As they only have a single element in hot water cyclinder, the boost and timed load would be linked together and they would use boost to warm up in day if required.

That would work fine if there were a single dual tariff meter, but you seem to be saying that there are two separate meters, leading to the issue you go on to describe. ...

sajeel said:
The only issue i have is if the economy 7 meter goes dead in the morning then i will have 2 supplies fed to either a change over switch or a relay that will switch from economy 7 supply to normal supply.

Indeed, one would have to have some arrangement such as that ... but WHY ...

... does your customer realise that having an E7 tariff is probably going to cost them a fortune in electricity bills if all they are using it for is an immersion heater? Daytime electricity is much more expensive with E7 than with a 'standard' single tariff, and one generally has to use at least 30% of one's electricity at 'cheap rate' before one even breaks even in terms of cost - which, in practice, nearly always means that it's financially disadvantageous to have E7 unless one has night storage heaters running from it. I suspect you probably should be advising your customer to contact their supplier and get rid of the E7 asap!

Kind Regards, John

sajeel · 12 Feb 2015

JohnW2 said:
sajeel said:

Usually the e7 meter is wired into main supply and works off peak which in london is around 11 - 7 however this flat appears to have a seperate meter and consumer for the eocmony 7 which was put in place to feed immersion heater but was disconnected. My plan was to run new feed and install this https://www.tlc-direct.co.uk/Products/SMTRTD7.html
As they only have a single element in hot water cyclinder, the boost and timed load would be linked together and they would use boost to warm up in day if required.

Click to expand...

That would work fine if there were a single dual tariff meter, but you seem to be saying that there are two separate meters, leading to the issue you go on to describe. ...

sajeel said:

The only issue i have is if the economy 7 meter goes dead in the morning then i will have 2 supplies fed to either a change over switch or a relay that will switch from economy 7 supply to normal supply.

Click to expand...

Indeed, one would have to have some arrangement such as that ... but WHY ...

Thanks john, looks like i will have to go back to do some further testing of economy 7, i understand that day rate on e7 meter is higher that's why a change over switch or a relay would be suitable so they use both supplies to heat up immersion heater.

... does your customer realise that having an E7 tariff is probably going to cost them a fortune in electricity bills if all they are using it for is an immersion heater? Daytime electricity is much more expensive with E7 than with a 'standard' single tariff, and one generally has to use at least 30% of one's electricity at 'cheap rate' before one even breaks even in terms of cost - which, in practice, nearly always means that it's financially disadvantageous to have E7 unless one has night storage heaters running from it. I suspect you probably should be advising your customer to contact their supplier and get rid of the E7 asap!

Kind Regards, John

Thanks john, looks like another visit to inspect their economy 7 setup and then make a final decision the customer wants to save money on bills and was told by a plumber that they can use economy 7 meter to heat immersion heater at night.

RF Lighting · 12 Feb 2015

sajeel said:
phatboy said:

This seems like you are working as an electrician?

Shouldn't an electrician know how E7 works, and the devices available to provide the requires switching without asking here? And probably not refer to cables as 'wires' ?!

Click to expand...

i know how e7 works but this e7 is wired different to usual which is wired together or a dual reading meter is used, in this flat the economy 7 is wired separately as for referring to cables as wires you can sleep on that thought,
I am not asking for a wiring diagram, i was asking for ideas but as usual some people on here just can control themselves

You've never seen E7 wired as a separate supply???

JohnW2 · 12 Feb 2015

sajeel said:
Thanks john, looks like another visit to inspect their economy 7 setup and then make a final decision the customer wants to save money on bills and was told by a plumber that they can use economy 7 meter to heat immersion heater at night.

Well, they obviously could do that - with the necessary tweaking to the wiring. However, as I said, if that immersion is the only thing being run off the E7 meter, then their electricity bills would inevitably be much higher with than setup than if thy got rid of the E7 and ran the immersion (and everything else) off a standard single-tariff supply. Get them to look at one of their bills and see what they are paying for 'day units' and 'night units', and compare the 'day unit' rate with what they would be paying on a single tariff (probably about 14p/unit). With E7, I currently pay 17.021p per daytime unit (but only 7.172 per night unit), but would only pay 13.41p per unit (day and night) if I didn't have E7.

Kind Regards, John

flameport · 12 Feb 2015

If the E7 is separately switched & metered, and you have only one element, the only product worth fitting is the Horstmann BX2000.

sajeel · 12 Feb 2015

flameport said:
If the E7 is separately switched & metered, and you have only one element, the only product worth fitting is the Horstmann BX2000.

spot on flameport
https://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/BX2000.htm

tlc have for sale i can pick up and fit.

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immersion wiring help

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