Switch timer

FreeBear

Scot_39 said: Note the as installed - timings to heat for one 3kW immersion to factory set 60C target are 99, 121 and 150sh minutes for the 3 smallest tanks (100,120 and 150l) - so at the 121 minutes 120l tank volume - thats 6kWh.

With an unvented tank, you could quite safely drop the temperature down to 50°C or even lower. The only way for bacteria to enter the tank would be from mains water supply (which is treated), so the risk from Legionella and other nasties is virtually zero.

Whilst storing hot water at 60°C will ensure bacteria are killed within minutes (at 50°C. it takes an hour or two), you have a high risk of scalding unless you have thermostatic controls on all hot taps - With a small child in the house, the scalding risk should be taken seriously.

Newbie_John

What does it say on the EPC rating:
https://www.gov.uk/find-energy-certificate

Quite often it indicates what heating systems you have in place and some major issues etc.

Gerry1

The flashing red light on the meter is your friend.

As described in the Meter Sanity Test, work out how many kW it says you are using at any given moment and compare it to the kW you expect from the devices that you know are switched on.

If you're using significantly more then power down and unplug sensitive items before turning individual circuits off at the consumer unit until you find the culprit(s).

inigma

Newbie_John said:

What does it say on the EPC rating:
https://www.gov.uk/find-energy-certificate

Quite often it indicates what heating systems you have in place and some major issues etc.

Most of my neighbours in the same block of flats, are rated C, a few are rated B, I am rated D...

Scot_39

FreeBear said:

Scot_39 said: Note the as installed - timings to heat for one 3kW immersion to factory set 60C target are 99, 121 and 150sh minutes for the 3 smallest tanks (100,120 and 150l) - so at the 121 minutes 120l tank volume - thats 6kWh.

With an unvented tank, you could quite safely drop the temperature down to 50°C or even lower. The only way for bacteria to enter the tank would be from mains water supply (which is treated), so the risk from Legionella and other nasties is virtually zero.

Whilst storing hot water at 60°C will ensure bacteria are killed within minutes (at 50°C. it takes an hour or two), you have a high risk of scalding unless you have thermostatic controls on all hot taps - With a small child in the house, the scalding risk should be taken seriously.

The tank is as above factory set to 60C - why I used 60C.

If own place - its a personal decision to disregard HSE - and the manual linked to includes instructions on where to find and how to adjust the setting if required - but if rented it's likely to impact landlord's LRA if a tennant were to do so.  (And unless the landlord tells them not to - the landlord would be held responsible - part of the HSE advice to landlords is to instruct tennants not to tamper with settings to comply)

But with a young child (or an elderly person ) in household  - it's probably better to be cautious.

Obviously heating incoming cold 10->50 will use less energy than input from 10->60 (temp diff 50 vs diff 40 = 25% more energy needed for 60C).

I heat mine to 60 as open vented.  It does seem wasteful to do so and then have to mix with cold of course - so my stopper goes in or basin goes under before reaches that temperature.

I've recently measured it as hot as 58 by running tap over meat thermomemeter - hardly scientific test or accurately calibrated device - before even a typical sink basin full - let alone bath type volumes - as you say a definite scald risk - for child (or elderly / infirm ) especially.

Of course scalding according to HSE should be taken care of by other measures. 

AFAIK last time checked - thermostatic mixer valves are now only mandatory in new builds or conversions - and only for baths in normal domestic scenarios (48C max) . But iirc also a wider and lower 44C requirement apparently exists in care and health service locations.

Spoonie_Turtle

55℃ might be a good compromise, if it stays there long enough.

The OP may also be interested to know that the default for water through heat pumps is to do a legionella cycle once a week (to 60℃), which may also be a good compromise if they want to err on the side of caution whilst reducing how much energy the hot water uses overall.

Scot_39

Getting off-topic for OP

Especially as we have - crucially - yet to establish HW tank is in fact source of the high daily energy consumption.

But doing a quick google - re legionella kill time number for 55C - came across the following site.

https://www.heatgeek.com/hot-water-temperature-scalding-and-legionella/

It quotes 90% kill times - 50C 80min-2 hrs, 55C 20 mins, 60C 2 mins

It makes some interesting comments re tank turnover rate etc vs temperature vs growth temps - to link to probable tank bacterial levels.

Would like to see it's arguments in proper scientific papers / detail elsewhere - but the chart of recommended min temp vs tank content turnover certainly an interesting idea.

Based on my low daily use etc wont be turning my thermostat down any.  But others might want to consider the arguments if genuinely considering risk vs savings from dropping temperatures.

Robin9

inigma said:

Newbie_John said:

What does it say on the EPC rating:
https://www.gov.uk/find-energy-certificate

Quite often it indicates what heating systems you have in place and some major issues etc.

Most of my neighbours in the same block of flats, are rated C, a few are rated B, I am rated D...

Most of my neighbours in the same block of flats, are rated C, a few are rated B, I am rated D...

Probably says more about the EPC assessment than anything else.

If D then that means your flat needs heat and it's coming from somewhere -  are you sure your floors particulalry in bathroom  aren't warm to the touch?

inigma

Robin9 said:

inigma said:

Newbie_John said:

What does it say on the EPC rating:
https://www.gov.uk/find-energy-certificate

Quite often it indicates what heating systems you have in place and some major issues etc.

Most of my neighbours in the same block of flats, are rated C, a few are rated B, I am rated D...

Most of my neighbours in the same block of flats, are rated C, a few are rated B, I am rated D...

Probably says more about the EPC assessment than anything else.

If D then that means your flat needs heat and it's coming from somewhere -  are you sure your floors particulalry in bathroom  aren't warm to the touch?

No i have checked none of the floors are warm.

Robin9

Hmmmm  - mystery 

Can you give us  the photos of the meter, consumer unit please ?