Why is water staying hot in evening (economy 7)

[wolfie882]

Hi,

We are running Economy 7 / immersion heater / Horstmann timer system for our hot water. In usual daily use the boost switch on the timer isn't used during the day so by evening the water is tepid at best.

However, when running the hot tap last night and again tonight around 8pm, the water was running piping hot. The boost switch hadn't been used.

The timer unit appears to be working properly (i.e. the 'Timed' indicator light goes out at the end of the Economy 7 overnight cycle). The clock is showing the correct time.

A friend suggested I alter the temperature setting on the thermostat from 60 to 50 degrees. But will this fix the problem? With the immersion heater sitting idle after the Economy 7 cycle switches off, won't lowering the temp on the thermostat mean we'll just have cooler water first thing in the morning?

Hope someone can cure me of my ignorance!

Thanks

 

[AndyPRK]

is the water hotter than usual in the mornings? scalding?

 

[PrenticeBoyofDerry]

Does the rod element on immersion have a cut out sensor?

 

[cjard]

A friend suggested I alter the temperature setting on the thermostat from 60 to 50 degrees.

Your friend appears to want you to die of Legionnaires' disease.

Actually even 60 degrees is only just hot enough to pasteurise the water - users of low temperature heating systems like heat pumps (where the water is stored at 40 to 50 degrees) are recommended to boost their systems to 65 once a week to prevent the risk of infection

 

[crystal ball]

The contacts on the E7 switch may be welded closed, if you are competent with a multimeter this can be tested

 

[wolfie882]

Hi all

Thanks for the swift replies.

AndyPRK - The water in the mornings is very hot, but I don't think it's any hotter than normal.

Crystal ball - Could I verify this visually (i.e. take the front cover off the timer)?

Thanks

 

[JohnW2]

Crystal ball - Could I verify this visually (i.e. take the front cover off the timer)?

Is there any indicator light, on the timer or elsewhere, which tells you when the E7 supply is powering the immersion?

Kind Regards, John

 

[wolfie882]

Hi JohnW2

Yes, there is a light labelled "Timed" on the Horstmann unit which comes on when the Economy 7 cycle starts (around 11.30 pm) and goes off at the end (around 7.30 am).

 

[JohnW2]

Hi JohnW2 Yes, there is a light labelled "Timed" on the Horstmann unit which comes on when the Economy 7 cycle starts (around 11.30 pm) and goes off at the end (around 7.30 am).

That sounds right, then. The timer/E7 switch contacts cannot be welded, then.

Kind Regards, John

 

[stem]

Some timers don't use the actual switching contacts to operate their 'on' light, so the contacts could still be 'welded' together.

 

[JohnW2]

Some timers don't use the actual switching contacts to operate their 'on' light, so the contacts could still be 'welded' together.

If it's an electronic one, that could be true.

Kind Regards, John

 

[stem]

Some of the mechanical programmers also had separate wiring for the indicators, but for a specific reason.

With a 3 port motorised valve, when the programmer has switched off, there is a live on the motorised valve's 'hot water not required connection' from the programmers HW off connection. This live is then electrically connected via the cylinder thermostat (but only when in satisfied mode) to the 'hot water on' terminal at the programmer. Therefore, if the programmer's light was wired directly to the same terminal, it would illuminate even though the programmer was set off. So to prevent this, programmer design dictated that they not be connected to each other.

OK, this refers to programmers for central heating and hot water, but I would imagine that for standardisation of components, that many manufacturers would adapt the same procedure for their E7 timers.

 

[EFLImpudence]

Let's start again.

We are running Economy 7 / immersion heater / Horstmann timer system for our hot water. In usual daily use the boost switch on the timer isn't used during the day so by evening the water is tepid at best.

Only if you have used some of it, otherwise it should still be relatively hot.

However, when running the hot tap last night and again tonight around 8pm, the water was running piping hot. The boost switch hadn't been used.

Had you, unusually, NOT used any during the day?

The timer unit appears to be working properly (i.e. the 'Timed' indicator light goes out at the end of the Economy 7 overnight cycle). The clock is showing the correct time.

Ok.

A friend suggested I alter the temperature setting on the thermostat from 60 to 50 degrees.But will this fix the problem?

That won't solve the problem if there is a fault, will it?
However, if you are able to do that then it is simple to determine if it is powered during the day.

Also, immersion heaters make a noise when working (they are big kettles) so, have a bath, can you here it?

With the immersion heater sitting idle after the Economy 7 cycle switches off, won't lowering the temp on the thermostat mean we'll just have cooler water first thing in the morning?

Yes, of course it will.

Hope someone can cure me of my ignorance!