Question about hot water CYLINDER

[Franki]

Hi everyone, hoping someone can help.

I've lived in the same rented flat now for a years, with no real issues with the hot water/heating etc. We've only got electricity, no gas. The heating is under floor heating, but we switch it on because the flat is generally quite warm. The hot water is heated via a large CYLINDER in the airing cupboard in my room - see pic below.

20200203_132502

• Franki
• 3 Feb 2020

At the end of December, the hot water stopped working. It just didn't seem to be heating up properly, only getting sort of tepid, rather than actually getting hot. At one point, while trying to figure out what was going on, I switched this switch on, but nothing happened. The switch is in the cupboard, next to the CYLINDER -

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• Franki
• 3 Feb 2020

Anyway, after several days of no hot water, and our lettings agent being unhelpful, they eventually arranged for an engineer to come out and he sorted it. He mentioned something about the thermostat, replaced a part, and the water went back to being nice and hot again.

Fast forward to now and we've just had our electricity bill for January and it's quite a lot higher than normal (I do a meter reading every month). It occurred to me that the "boost" switch had been switched on all month, so I switched it off last night. This morning, I went to take a shower and the water was back to being tepid again. So, I switched the "boost" switch back on and now the water seems to be heating up. Am I right in thinking that there must still be something wrong with the system if the water's only heating up when this switch is on?

 

[stem]

There are two electric heating elements fitted to the hot water cylinder. One (the bottom element) is only used when an 'off peak' supply is available. This heats the water up at times when there is not much demand for electricity (ie during the night, or late afternoon, depending upon your chosen supply) so the electricity is discounted and costs about one third of the normal rate.

However, this can run out during the day, and so the boost is provided (the top element). This will heat the hot water on demand when switched on, but at the full rate.

Sounds like you have left the boost switched on and have been heating your water using the expensive electricity. Switch the boost off and only use it as a top up if you happen to run out of hot water during the day, and make sure the timeswitch (if is it controlling the bottom element) is set to coincide with your cheaper electricity.

 

[Franki]

Right ok, but I switched the boost off last night, so shouldn't the "off peak" supply have kicked in overnight and heated the water? This morning there was no hot water?

 

[SFK]

I would be looking at that timer and see if it is set to the correct time, and if it is rotating.

 

[stem]

make sure the timeswitch (if is it controlling the bottom element) is set to coincide with your cheaper electricity.

If that doesn't fix it, the bottom element might need replacing.

 

[Franki]

Thanks stem and SFK for both getting back to me so quickly.
Ok, so this is a closer look at the timer. At some point, it's been set wrong, as it was showing the current time as 4am... I've just set it to the correct time!

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• Franki
• 3 Feb 2020

Out of interest, what times would you recommend setting the pins to? They're currently at 4am and 10am, but they're both in the "ON" circle, when I think the 10am one was probably meant to be in the outer/off circle. We're on Economy 7, and our off peak hours are 12.30-7.30am, so is it better to have it come on AND go off during these hours?

 

[SFK]

Frank,
IGNORE below, as I feel Stem is correct (in following message) and I am wrong.
SFK



I think you may still have an problem.

The fact that the timer is set to be ON all the time, I think suggests that this timer is probably working.
And depending on how it is wired this timeswitch might be:
1) heating the water whenever the E7 is on. or
2) Heating the water whenever your use the Boost switch.

And to be honest as you are renting it might be time to get Plumber back in.
SFK

 

[stem]

That looks like the timeswitch switch that controls when the bottom heating element is on.

Not only does it need to be set to the correct time, but the set 'on' time needs to correspond with the 'off peak' supply and this can vary according to your electricity tariff. Your electricity supplier will be able to advise, it might even be on your bill. I normally set them so that they don't switch on until half an hour into the off peak rate.

 

[Hugh Jaleak]

Cheap Rate Electricity was often known as 'Economy 7' or 'E7', as it was the 7 hours through the night when demand for power was traditionally lower. Usually between 01.00 and 08.00 hrs, the system was set up to allow storage heaters and E7 hot water immersions to heat up during this period.

Can you check your electricity meter? The newer types have 2 readings, for peak and off peak, and change over with an audible 'click' at 01.00hrs, putting the supply onto cheap rate until 08.00hrs. If this is the case, you need to set the time switch to the correct time, and program it to turn the immersion on during off peak hours.

If it works correctly, it should then heat the whole tank overnight on cheap rate. Boost (expensive rate) is then only require to top up during the day if you run out of hot water.

 

[muggles]

thought Economy 7 has a separate meter?

This is a 4 month old post. I'm sure it's sorted by now

 

[stem]

thought Economy 7 has a separate meter?

As has been said the problem is probably resolved, but as this is a good question which is asked fairly frequently, I thought a reply might be useful.

You could connect the immersion heater directly to an 'off peak' supply, but the problem then, is that if you ran out of hot water, you couldn't switch it on during the daytime.

Fitting a timeswitch to a permanently energised electricity supply allows the immersion to be set to only be 'on' during the 'off peak' period and thus make use of the cheaper electricity. But, if required, the timeswitch can be overridden to allow the immersion to be used during the daytime, albeit at the full price tariff.

A further advantage in the case where an existing installation is converted to benefit from an off peak supply, is that the existing immersion wiring can be used without any modification other than the addition of the timeswitch.

 

[Madrab]

The old ones were like this and had the mechanical timeswitch as per or similar to pic 2 that would swap circuits in the consumer unit -

new meters are like the white one in the 2nd pic and it either alternates between the 2 rates or there's a button to switch the readings and integrated electronic switching.

 

[Hugh Jaleak]

Mine is the newer type, you hear it change with an audible 'click' at 0100 and 0800 hrs.