Water Immersion Tank linked to E7 meter

ceanth

Hi all,

I have purchased a property which has an immersion water tank and an ecomony 7 meter.

I have never used an immersion water tank before so I was wondering if somebody could help clear up something which I am confused about.

Should the immersion water tank be linked to my Economy 7 meter? I am currently with EDF which give me a day rate and a night rate. My understanding was that the water in the tank would heat up over night and then distribute during the date. The issue is how do I "program" the water tank to only turn on during the night? There is an on off switch and a box which gives me a boost option. I do not see any options to specify a time when I would like for the tank to turn on.

The water tank is a Tribune TD180

The boost switch is Electrisaver E15

EDF give me cheaper rate electricity between 12:30am - 7:30am.


Thanks,
c

Owain_Moneysaver

The Electrisaver E15 is a boost timer only. It does not control Economy 7 switching.

EITHER

You have two immersion heaters, one at the bottom of the cylinder for overnight heating and feed from the off-peak-only consumer unit along with the storage heaters, and one near the top of the cylinder for boost and controlled by the electrisaver.

OR

Your water heating isn't on Economy 7 and will cost you a fortune to run.

GolfFoxtrot

In my old flat the water heater had two switches, one for heating overnight (econ 7) or one whenever we needed it.
Check if yours is thesame

Cardew

It depends on the wiring in your house. With some properties electrical circuits are only live during the 7 hours and the immersion heater would be on one of those circuits.


Some houses(most these days) have all electricity at cheap rate during the 7 hours.


It is easy enough to switch on the immersion heater and watch the meter.


P.S. Check if your timing changes by one hour when the clocks switch from BST to GMT.

Richie-from-the-Boro

If its an E7 / E10 / or E anything spec it should already be PartL spec, due to the higher than normal storage temperatures the capability of the insulation to preserve the temperature of the water the type of insulation has a very very low standing heat-loss [one kW per day (kWh/24h) on a 125 litre cylinder] permissible thermal transfer rate from the 60mm of insulating foam, modern ones have the additional benefit of recessed immersions and thermostats to reduce even further energy wastage. All dual PartL cylinders have a top up facility (URL="https://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/HOE15_Datasheet.pdf"]here's yours[/URL) [see below] and is usually operated by a standard 60 minute top-up water controller such as the Horstmann unit also shown below. Yours is a modern version of the picture below and is as Owain Moneysaver said a boost timer only for variously water hearing, panel heaters, towel rails etc.

The Tribune TD180 is a good quality water heater designed for E7 / E10 / or E anything spec and able to have x2 separate 3kW heating elements installed - but has it ? Also those x2 heating elements should each have a cable coming from them to a water controller as Cardew said. This water controller ordinarily tele-switches the cheap rate night element on and off [automatically and out of your control] at the bottom of the tank. The other top element is the boost element controlled by yourself on expensive day rate.

If you do not touch the E15 boost controller and you get a tank of nice hot water every morning its still tele-switching on and off. You have checked your tariff and get 'cheaper rate electricity between 12:30am - 7:30am'. Have you got x2 elements both with wiring going somewhere and what is the somewhere they are going to ?





The top element [top-up-day rate] will give a couple of big sinks of hot water when used, the bottom element [E7-night rate] will give a full bath and a couple of sinks of hot water. Heat loss is not linear to the volume of water, the bigger the mass the slower the loss rate, eg [figured below are 'ish' but about right] :

1 kW per day (kWh/24h) on a 125 litre cylinder
1.5 kW per day (kWh/24h) on a 250 litre cylinder
2 kW per day (kWh/24h) on a 300 litre cylinder

Smiley_Dan

Are those measured figures or figures from the manufacturer?

If they are from the manufacturer you should know the assumed usage pattern used to generate them and the fact that only a tiny amount of pipe losses are allocated, way below reality.

I don't think I have ever heard of such low figures in real life. I would say more like double that normally.

Not that it adds up to much with our low energy prices in the UK, but once reality bites...

Richie-from-the-Boro

Smiley_Dan wrote: »

Are those measured figures or figures from the manufacturer?

If they are from the manufacturer you should know the assumed usage pattern used to generate them and the fact that only a tiny amount of pipe losses are allocated, way below reality.

I don't think I have ever heard of such low figures in real life. I would say more like double that normally.

Not that it adds up to much with our low energy prices in the UK, but once reality bites...

Hiya Smiley Dan, they are precisely """'ish' but about right""". The figures were and are minimum to the PartL CHeSS Best Practice guidelines for insulation.

Size

---

Loss kWh/24hrs
120ltr

---

1.05
150ltr

---

1.23
180ltr

---

1.32
210ltr

---

1.58
250ltr

---

1.84
300ltr

---

2.1

Smiley_Dan

But the trouble is those are not real world figures - they just relate to the losses from the tank. Good thread on this here: http://www.ebuild.co.uk/topic/16283-losses-from-water-cylinder/ .

It surprises me how little insulation we put around tanks, given the temperature deltas. Best practice for space heating may be what, 200mm+ around your house with the average winter temp delta 15C, say? But we only put a few centimetres around a hot tank with a temp delta of 40C+! Granted, not as much to cool down, but...

This is why the more I look into it the more I like modulating instantaneous water heaters. Modulating so they reduce their draw according to the pre-heat from the tank, e.g. solar, ASHP heating to 35-40.

Cardew

Smiley_Dan wrote: »

But the trouble is those are not real world figures - they just relate to the losses from the tank. Good thread on this here: http://www.ebuild.co.uk/topic/16283-losses-from-water-cylinder/ .

It surprises me how little insulation we put around tanks, given the temperature deltas. Best practice for space heating may be what, 200mm+ around your house with the average winter temp delta 15C, say? But we only put a few centimetres around a hot tank with a temp delta of 40C+! Granted, not as much to cool down, but...

I take your point, but any heat lost from the tank usually heats the fabric of the house and so for much of the year is not wasted; and what would we do without an airing cupboard?


The British Standard for losses(stamped on some cylinders) is for water kept at 65C over 24 hours and are similar to those shown in Richie's post. Do we keep water at 65C 24/7?


Even if you are correct that real losses are double those shown by Richie above, it is still not a huge penalty.

Richie-from-the-Boro

Smiley_Dan wrote: »

But the trouble is those are not real world figures - they just relate to the losses from the tank. Good thread on this here: http://www.ebuild.co.uk/topic/16283-losses-from-water-cylinder/ .

It surprises me how little insulation we put around tanks, given the temperature deltas. Best practice for space heating may be what, 200mm+ around your house with the average winter temp delta 15C, say? But we only put a few centimetres around a hot tank with a temp delta of 40C+! Granted, not as much to cool down, but...

This is why the more I look into it the more I like modulating instantaneous water heaters. Modulating so they reduce their draw according to the pre-heat from the tank, e.g. solar, ASHP heating to 35-40.

O/P ecomony 7 meter, cheaper rate electricity between 12:30am - 7:30am

HiYa Smiley Dan,

I'm well known to have somewhere between little and zero time for expensive eco solutions to a problem that does not exist.

An inadequate 11kW or a decent 27kW plumed in to a UK 24kVA with standard 100A cut-out is going to need uprating from domestic to commercial 100amps x 230 volts / 1000 = 23 kva supply. The 27k unit is going to need 3 x 40 AMP double pole breakers .. .. that on its own is 120a. Christmas dinner can often exceed 80a add the 120a to that and you are running at a 200a domestic supply - double the UK domestic standard.

Now the O/P's existing needs are being adequately met for a tiny fraction of the cost and I have not added the £300 to £600 for the supply of the electric tankless plus god knows for a commercial supply / maintenance / wiring / and tariff. Like I said I have little time for """expensive eco solutions to a problem that does not exist"""

Smiley_Dan

Sorry, my previous reply to Cardew wasn't posted for some reason.

It is a problem. There is significant energy lost from hot water cylinders.

It has nothing to do with "eco" or green-wash, it is physics, only far more complex than the simplistic assessment procedures allow.

In terms of finances I agree it is not a big issue. At the moment.