Economy 7 - Hot water not working

Heely

Wait, so when the immersion failed, so did the storage heater?? Or are you saying that it’s off anyway and nothing to do with the immersion failing?

The storage heaters are working fine. They are switched off for Summer. Nothing to do with the immersion failing. 

tim_p

The reset is generally found on the stat itself, which is attached to but normally separate from the immersion, so with the lid off the immersion there will be the incoming cable, 3 wires, one going to an earth terminal, another going to the immersion itself and the other goes to one side of the stat. The other side of the stat goes to the other connection on the immersion.  This applies to a top fitted immersion but it’s so long since I’ve looked at the shorter side mounted immersions that I might be wrong, although the basics should be the same as it’s doing exactly the same job. Stats fail and are a simple job to replace. Replacing an immersion involves draining the tank and you’re usually lucky to get an immersion out without huge effort and risk of damaging the tank, especially if it’s been in there a good many years. 

thorganby

Heely said:

Gerry1 said:

Essentially there are only three possibilities.

• No supply voltage is reaching the element.  Culprits include the E7 timeswitch / contactor and strange wiring / operation of the Horstmann timer.
• The thermostat is faulty or not calling for heat.  Turn it to maximum.
  
• The element is faulty or has an open circuit connection.
  

A nocturnal test with a voltmeter (after the meter has been observed to switch to night rate) should yield results.

Tested - No supply voltage is reaching the element.

Was the original element actually tested to prove that it had failed before it was replaced or was it simply assumed that it must be the element?

If no volts are getting to the new replacement element it is likely that this was the case before it was replaced as only three wires have been reconnected.

Did the "Timed" light illuminate on the Horstmann Quartz when you checked for volts during off peak time?

Nobody can know from the limited information provided how your immersion heaters have been wired, the Horstmann Quartz was obvious fitted by a cowboy!

It may have been fitted to simply provide a timed boost function to the upper immersion, so more investigation by a competent person is required to proceed any further.

Gerry1

Thinking outside the box for a moment, we're all assuming that the old immersion heater had failed.  That's probably true, but it's possible that the old heater and thermostat were both OK and that there's a fault somewhere else.  Not particularly likely, but something to bear in mind if it remains a difficult nut to crack.  The Horstmann installation seems a bit weird and unprofessional, so there may have been a Restricted Hours Tariff that's left a legacy problem.

Update: beaten to it by Thorganby.  Telepathy at work !

Talldave

So many unknowns - is there a fused spur switch somewhere with a blown fuse?

The on peak MCB doesn't look like it's the original. Why is it 32A? Suspect the "upside down" cowboy fitted it to overcome RCD tripping.

I wouldn't let my neighbour change my immersion element.  But each to their own!

tim_p

As Talldave says, too many unknowns. Heely, did the neighbour who ‘changed the element’ drain down the tank?  Asking as I’m curious as to exactly what was changed. Perhaps post a photo of the new element with the lid off (it should be dead as it’s E7 and out of those hours but... take care. )

Heely

thorganby said:

Heely said:

Gerry1 said:

Essentially there are only three possibilities.

• No supply voltage is reaching the element.  Culprits include the E7 timeswitch / contactor and strange wiring / operation of the Horstmann timer.
• The thermostat is faulty or not calling for heat.  Turn it to maximum.
  
• The element is faulty or has an open circuit connection.
  

A nocturnal test with a voltmeter (after the meter has been observed to switch to night rate) should yield results.

Tested - No supply voltage is reaching the element.

Was the original element actually tested to prove that it had failed before it was replaced or was it simply assumed that it must be the element?

If no volts are getting to the new replacement element it is likely that this was the case before it was replaced as only three wires have been reconnected.

Did the "Timed" light illuminate on the Horstmann Quartz when you checked for volts during off peak time?

Nobody can know from the limited information provided how your immersion heaters have been wired, the Horstmann Quartz was obvious fitted by a cowboy!

It may have been fitted to simply provide a timed boost function to the upper immersion, so more investigation by a competent person is required to proceed any further.

The original element was not tested to prove it had failed. Good point. Once removed, there was indication of burn around the screw. (See pics sent earlier).
The "Timed" light did not illuminate on the Horstmann Quartz when I checked for volts during off peak time.
Horstmann Quartz was fitted circa 2013 and has had no problems to date. 
Immersion heater element changed 2015.  

Heely

Talldave said:

So many unknowns - is there a fused spur switch somewhere with a blown fuse?

The on peak MCB doesn't look like it's the original. Why is it 32A? Suspect the "upside down" cowboy fitted it to overcome RCD tripping.

I wouldn't let my neighbour change my immersion element.  But each to their own!

Not sure what a fused spur switch is or looks like. Pics of the electrical set up were posted to the forum earlier. 
A separate electrician fitted a new MCB couple years ago. Not sure why its 32A. What should it be?

Heely

tim_p said:

As Talldave says, too many unknowns. Heely, did the neighbour who ‘changed the element’ drain down the tank?  Asking as I’m curious as to exactly what was changed. Perhaps post a photo of the new element with the lid off (it should be dead as it’s E7 and out of those hours but... take care. )

The neighbour did not drain the tank. Pics posted below. 

Heely

New element. 
Full view of tank, water switch heater and Horstmann Quartz