On peak off peak wired incorrectly?

Avo Mk8 said:

So far it appears:

• (anybody care to comment on the presumably timed neutral feed to the contactor from meter, what's the other to the Henley?)

Click to expand...

The meter timed auxiliary contact has N in sourced from the Henley and N sw out to contactor.

It does seem there has been some interference with the original setup, for unknown reasons.

What needs investigating is;

Do both immersion heaters work when powered, if not replace as required,

Do the thermostats in each heater control that heater correctly when set to the appropriate temperature, if not replace as required,

Is the top heater controlled by a switch labelled ON Peak (preferably the upper switch to avoid confusion) which is supplied from the ON peak section of the Consumer unit, if not reconnect / relabel as required,

Is the lower heater controlled by a switch labelled OFF Peak (preferably the lower switch to avoid confusion) which is supplied from the OFF peak section of the Consumer unit, currently missing an MCB to be able to do that, if not reconnect / relabel as required,

Have we established whether there is a Horstmann E7 style water heating controller in the property?
The most worrying aspect of this is that four electricians have already visited and failed to sort what appears to be a fairly simple problem for anyone worthy of that title.

Avo Mk8 said:

Not in my opinion!
I'm thinking what you call a knob is the cover of each immersion heater, which has the thermostat adjusting knob in it.

The bottom immersion is there to heat the whole tank, and that is the one normally powered by off-peak.
The upper immersion is for a "boost" if you run out of hot, normally fed from on-peak.
Does the light on the on-peak switch actually stay on all the time?

My first thought is that they are wired the wrong way round, but at this time of night I could be wrong. No doubt someone will be along to comment!

Click to expand...

Yes sorry the black cap is what I am referring to (thermostat underneath I believe)

The photo I took was at 10am yesterday which would mean the light should be off - but yes light stays on always. Attached another photo which was taken just now at 10:25.
When we turn it off we are left without hot water which sparks my concern that it’s all wired incorrectly (or is it as simple as labelled?)

Avo Mk8 said:

So far it appears:

• the 'off-peak' section of the consumer unit seems to be fed from a DNO/Eon contactor, so should actually be 'off-peak'!
• (anybody care to comment on the presumably timed neutral feed to the contactor from meter, what's the other to the Henley?)
• the right hand 'off-peak' MCB position labelled 'immersion' has had the breaker removed
• so we don't know where power for the immersion heaters is now coming from.
• the bottom immersion heater works, but seems to need a new thermostat
• the top immersion heater does not work, but we don't know if it's lack of power, fuse, thermal cutout or faulty element etc.
• the flex to each of the immersion heaters seems to be transposed compared with what you would expect.
• the 3 x 500W Dinplex (presumably panel, not storage) heaters in the hallway are powered from peak rate electricity, which may be correct for that type of heater,

You would think it would be relatively straightforward for a competent electrician to sort this out !

Click to expand...

Majority of bullet points are a little tricky for me to understand but thank you, will keep these all noted.

Just a point re your last point as I struggle to understand this too re the panel heaters and you are correct they are panel not storage.
So each of these (hallway, room 1 and room 2) have their own switch - shouldn’t be connected to on peak or off peak at all. When I do my maths to work out the costs (wattage x hours on x day rate/night rate) let’s take the highest day rate for example:
0.5KW x 5 hours x 0.44p kw/h = £1.1 so it should be costing me approx £1.10p to run these for 5 hours a day however when I pop these on and watch my ‘smart meter’ (the little screen thing I have plugged in at home) it drinks pounds for fun… and uses far more than £1.10p
I was under the impression these would not run off the on peak / off peak and just simply on day rate / night rate

brianmoooore said:

Have we established whether there is a Horstmann E7 style water heating controller in the property?
The most worrying aspect of this is that four electricians have already visited and failed to sort what appears to be a fairly simple problem for anyone worthy of that title.

Click to expand...

Hi Brian
No I do not have this inside / or outside my home.
Thank you

I'm also shocked that 4 electricians haven't been able to play a fairly simply game of "I wonder what is supplying this" and make a little progress.

@MeganS I'll try and repeat what others have said in simple terms. As far as I can tell the original design was that the very right hand bit of your consumer unit is designed to be powered only during off-peak times.
So it looks as though the original design was for the storage heaters and the lower immersion to be powered at night.
The upper immersion was probably intended for obtaining extra hot water and likely was intended to be manually switched on and off as required.

(to complicate matters some modern storage heaters can also be wired to also be used during the day, but ignore that for now)

The primary goal for any electrician (as said above in various ways) is identifying how the off-peak supply to the lower immersion was intended to work when originally installed.
I'm 99% sure there is a cable from the consumer unit to one of the two marked switches.
I'm also fairly sure that it isn't now connected to where it was once connected, as the breaker is missing.

I could speculate that if the lower immersion became faulty, someone could have decided the fault was it wasn't getting power (mis-diagnosis if they checked during the day) and decided to give it power from somewhere else.

But any electrician is simply looking to find the cable that was originally connected to the very right hand space on your consumer unit, check which switch it goes to, and check that in turn is connected to the lower one.
They would need to re-fit the missing circuit breaker (MCB) too.

Once that is done, we get into secondary issues, like does the immersion heater and it's stat work, and how is the on-peak unit powered. But at least the on-peak could then be turned off to immediately save you some money.

If you don't mind, post whereabouts in Essex you are (roughly). You've been messed around so much that someone might offer to help, as the diagnosis should be a quick job.

If there's no E7 or similar, then there should be a feed for the immersion heaters from the off peak section of the CU.
I'm beginning to wonder whether there was a fault on the off peak feed (missing MCB), and a simple work around, to get a full cylinder of hot water back, was to swap the bottom immersion to the non off peak switch in the airing cupboard.
A competent electrician should be able to work out what the problem is, but not necessarily fix it, within half an hour

Edit: Looks like timhoward and I have come to the same conclusion at the same time!

My earlier post was too cryptic. If you do not live far from the Dartford Crossing, which is 10 minutes away from me in Essex/Havering, then I will pop round and have a look at what's what and take some photos for the fine folk who have posted so far to examine. And I will give you my 'tuppeny worth' too. I will not do the remedial work but I will visit for free as long as you are within 30 minutes of the DC. It will get me out of the house. Being married to my dear wife for 35 years means responding to a damsel in distress is a speciality of mine Daytime please.

marconi said:

My earlier post was too cryptic. If you do not live far from the Dartford Crossing, which is 10 minutes away from me in Essex/Havering, then I will pop round and have a look at what's what and take some photos for the fine folk who have posted so far to examine. And I will give you my 'tuppeny worth' too. I will not do the remedial work but I will visit for free as long as you are within 30 minutes of the DC. It will get me out of the house. Daytime please.

Click to expand...

You didn't say how many sugars you want in your tea....

OP, you should take up this offer. Then you will be in a better position to inform your local electricians what the problem actually is.

And, it will convince you never to use any of those electricians that have visited already, if they cant figure out the problem.

@marconi
is one of the few people who actually understands electricity and how it works, If you have the opportunity to serve him a cup of tea, your endeavours will not be wasted.

marconi said:

My earlier post was too cryptic. If you do not live far from the Dartford Crossing, which is 10 minutes away from me in Essex/Havering, then I will pop round and have a look at what's what and take some photos for the fine folk who have posted so far to examine. And I will give you my 'tuppeny worth' too. I will not do the remedial work but I will visit for free as long as you are within 30 minutes of the DC. It will get me out of the house. Being married to my dear wife for 35 years means responding to a damsel in distress is a speciality of mine Daytime please.

Click to expand...

Apologies I missed replying to the message within the many lovely explanations from all the others.
I have sent you a private message with further details
Thanks so much

My ex apprentice (now an excellent qualified spark) now lives in London and has his own company

Once Marconi has been I can send him a message.
I don't know if he is doing domestic work or not but I can check

baldelectrician said:

My ex apprentice (now an excellent qualified spark) now lives in London and has his own company

Once Marconi has been I can send him a message.
I don't know if he is doing domestic work or not but I can check

Click to expand...

That’s very kind, thank you
I am catching up with Marconi via phone call tomorrow so we’ll update you all as soon as he’s had a look

First Megan and her baby were very pleased with the generous help and advice from those who responded . I visited today and took a few photos and found out a few things:

1. There is a time switched off peak supply controlled by the meter and connected to the far right off peak main switch of the CU. I saw this supply turn on during my visit. The first picture below shows the peak and off peak supplies to two FCUs for the one and only storage heater.

2. Both immersion elements are sound as are their thermostats. However neither thermostat is a safety 'stat. Both were set to 55C. I have recommended the rod 'stats are changed to safety stats. The elements are both 11 inch. Each elements draws 13A. The switches for the elements are wrongly labelled. The top one labelled off peak feeds the upper elements and the lower one labelled on peak feeds the lower element. But see a later comment at 5 below.

3. The 24 hour supply for the storage heater is fed from the flat FRC. The off peak supply is from the first rcbo (B20A) to the right of the off peak main switch.

4. All the wall dimplex heaters are fed from the flat FRC and thus from the peak supply side of the board.

5. The two immersion heater switches are connected to the same peak supply B20A mcb - the one above which you see my ampclamp. I confirmed this by turning both 'stats to maximum and my amp clamp measured 26A and mcb buzzed.

6. The 13A socket for the water pressure pump is spurred off the immersion heater switch above it - you can see the wago connections behind the switch above the socket. Whereas the flat us wired in old colours the paralleling of the immersion heater switches and socket is done in new colours. The supply to all three from the board is the original old colours.

7. The second right B20A rcbo on the off peak supply says it is a for heater on the outside of the board bit is marked up with 'Imm' inside. I don't have a picture for that. There is an old colour cable connected to it but I could not establish where its goes. I suspect it is terminated in connectors behind the lower immersion heater switch or the 13 shower pump socket but I could not see if this was the case. I did not look behind the surface mounted 13 A socket - all a bit too awkward for me to do. Disconnecting this cable run, it measures open circuit between L-N.

8. I did not check how the lounge storage heater programmer was set up.

In brief then the only Eon controlled off peak heater is the storage heater in the lounge. Whether water heating uses off peak is by chance because Megan did not know that the whole flat (ie all the peak side loads) uses the lower tariff when it switches. (She has E10 which I checked on her bill). A phone call to be made to determine the off peak time slots but I have passed what I think they maybe and how to detect when off peak is available - the lounge right FCU neon light. The shower is fine albeit the flow rate is low which means that on the highest power setting the water temperature is too hot to bear. On the low power setting the water temperature is fine for a bloke but perhaps not hot enough for a damsel ;-). On the cold setting the water is cold and there is only a cold water supply to the shower.

The major work it seems to me is to provide peak and off peak supplies to the two IH elements, swap the stats to safety ones and provide a dedicated FRC supply perhaps for the shower pump 13A socket - or fit an fcu spurred peak IH switch.

I have to sign off now as wife home from hospital.

PS: I left the board with some postits on it but forgot to take a photo.

But the question remains....

How many sugars?

littlespark said:

So it’s wired --- over t!t, then?

Click to expand...

Sort of. The tank elements only have one shared feed using one 2.5mm2 cable off a B20A on the peak busbar. I have advised Megan only to use one element at a time. Something has happened in the past to make this so and to change the pattern/brands of the IH iso switches.

The extreme RH MCB position on the CU is blanked off and marked spare, but was originally labelled 'immersion'. Is there any evidence inside as to what this might have been about?
You say both switched cable outlets for the immersion heaters are connected back to the CU by a single 2.5mm2 T&E. Does the feed go to one and then spur on to the other? If so, does this look original?

brianmoooore said:

The extreme RH MCB position on the CU is blanked off and marked spare, but was originally labelled 'immersion'. Is there any evidence inside as to what this might have been about?
You say both switched cable outlets for the immersion heaters are connected back to the CU by a single 2.5mm2 T&E. Does the feed go to one and then spur on to the other? If so, does this look original?

Click to expand...

1. Theis new MK CU was installed when Megan moved in.

2. I suspect strongly that the RH mcb position you mentioned was for the off peak IH element. It is now fitted second right to off peak MS but does not power anything. I reckon one of the original three B20A rcbos (two for SHs and one for off peak IH) on the right of the off peak mainswitch has been moved to the right of the far left peak main switch to supply the hall dimplex.

3. After Megan bought the flat but before she moved in the electric space heating was renewed in toto.

3. The original red black 2.5 mm2 feed from peak side B20A marked IH arrives at top IH iso. Spurred off it in brown blue is a drop to the lower IH iso. Spurred off lower IH iso is a drop to the new 13A socket for the water pump.

So it's looking likely that the conclusions that timhoward and I came to at exactly the same time, in posts 31 and 32, that there was a fault with the off peak supply to the lower immersion are correct? This was then bodged to get the lower immersion working again, most likely without telling the customer that the cost of water heating would be doubled.

The single feed to the immersions could perhaps be used as is by installing a Horstmann Economy 7 type controller, fed from one of the existing FCU's, which could output to the two immersions, as it ensures only one can be powered at any one time. So setting the timeclock to E10 periods would power the bottom immersion on cheap rate, and the rest of the time the boost button would be available for a top-up, on peak rate of course.
But does the pump draw too much to be left on that citcuit as well, I guess it doesn't consume much?

brianmoooore said:

So it's looking likely that the conclusions that timhoward and I came to at exactly the same time, in posts 31 and 32, that there was a fault with the off peak supply to the lower immersion are correct? This was then bodged to get the lower immersion working again, most likely without telling the customer that the cost of water heating would be doubled.

Click to expand...

Yeah -we did ok!
But I can't get my head around someone's decision making process. I'd have thought the choices (most preferable first would be)
1) Actually fix it and sort out the off peak supply
2) leave lower IH connected to peak supply and fit a ?radio time switch. Customer has control over when there is hot water and can heat it up overnight.
3) leave lower IH connected to off-peak supply - Tank heats overnight at cheap rate, customer has hot water at better price for some of the day
4) leave peak connected to both IH's. Overload the circuit 24/7 and pay through the nose for perpetual heating of water.

Only a right muppet, or someone completely ignorant about how it worked would choose option 4.

Avo Mk8 said:

The single feed to the immersions could perhaps be used as is by installing a Horstmann Economy 7 type controller, fed from one of the existing FCU's, which could output to the two immersions, as it ensures only one can be powered at any one time. So setting the timeclock to E10 periods would power the bottom immersion on cheap rate, and the rest of the time the boost button would be available for a top-up, on peak rate of course.
But would the pump draw too much to be left on that citcuit as well?

Click to expand...

Your idea should be option 1a in my list. Nice!

Avo Mk8's suggestion of the E7 is the way to go. In fact, I had nearly finished typing a virtually identical post when he posted, so deleted mine.

I think the problem with the peak/off peak was suggested way before #31 and 32.

Its just good to have a proper 'eyes on' examination of a problem

littlespark said:

I think the problem with the peak/off peak was suggested way before #31 and 32.

Click to expand...

It was only in post 30 that is was determined that there was no Horstmann E7 or similar controller fitted anywhere, which would have only required a single 24 hour supply.
There are efficiency advantages to be had by using a controller in preference to the supplier's off peak switching - the off peak supply starts heating the water at a time of day when there is likely to be little demand for hot water, finishes heating it after three hours or so, then spends the rest of the night bouncing off of the thermostat, as heat leaks from the cylinder.
Ideally, you want the cylinder to finish heating just before the end of the off peak period.