Economy 7 immersion boiler with timer only for top element? Confused with how it's meant to work!

greenguppie

Assuming we are not looking at a bodged job:

The top heater may have failed to come on during boost because:
1. The water is already hot and the thermostat for the upper heater does not allow further heating at this time.
2. The top heater is faulty
3. The top heater thermostat is faulty
4. The top heater thermostat is set too low to allow the heater to operate

With regards to the lower heater operating:

1. Double check, and adjust if necessary, the current time of the clock.
2. Double check, and adjust if necessary, the timings you have set. As per the instructions, there are 3 settings. The first should be set to 12.30am - 7.30am (or to suit your off peak electricity timing). The other 2 periods should be set to a time after 7.30am, and the on and off times should be the same, so they effectively do nothing.

If the lower heater still operates during the peak period, then I'm afraid we are looking at a bodge job.
In which case, best to contact the landlord and get him to send a compentent electrician around. Don't even allow the electrician through your door unless and until you have checked he is competent.

With regards to heating water, hot water rises, so only the water above the applicable heater will be heated. If you look at the lower heater, that is about 6" above the bottom of the tank, so those bottom 6" will never be heated even if the lower heater does work.
There is no significant issue about bacteria in the water, as the water is drawn from the top of the tank, so it will always be hot, assuming you are heating it.

If you allow the water tank to heat up (it may take many hours, even 2 nights on off peak only), you may be able to identify which heater is working.
First of all, if it's the lower one, you will have a full tank of hot water (such as for a decent bath) whereas the upper one will only heat half the tank, so you may find yourself running out of hot water unless you reheat it.
But that may be difficult to judge.
So see the brass surround between the white immersion cover and the tank? Be careful, but that should be hot for the upper heater.
It should be hot either because that heater is working, or the lower heater is heating the water around it
Then check the same on the lower heater. It will be cooler, but won't be cold unless the lower heater is not working. The upper heater will not heat the water around the lower heater.

Gerry1

Leave the On Peak switch off and the Off Peak switch on.  Look at the meter on the wall and wait until the night rate kicks in.  If you then jiggle the Off Peak switch next to the tank (BTW, it's not a boiler) a few times and listen closely you'll probably be able to hear it spark and the lights may flicker very slightly.  That will confirm that the lower heater is working.

Needless to say, if the hot water goes cool and then cold that confirms the lower heater isn't working, either because it's failed or it isn't receiving a supply.  Either way, it would be down to the landlord to get it fixed.

coffeehound

^ OP has already established that the lower immersion heater does not draw any current overnight

Gerry1

coffeehound said:

^ OP has already established that the lower immersion heater does not draw any current overnight

Agreed, it seems likely that the lower heater isn't working for some reason, but 1.7kWh was drawn overnight.  Probably just the baseline load of the fridge and the freezer etc, but there's no harm in making additional checks; the lower heater may not draw much if its thermostat is set low and the upper heater is set high.

The 'spark and flicker' test has the advantage of being instantaneous, as does looking at the 1000 Imp/kWh light on the meter.