Economy 7 - how to set timer?

mjtf24

Hi all, I'm trying to figure out my Economy 7 setup and I just can't get my head around how to set the timer (top right knob). I just had the lower element in my water heater replaced, but now need to make sure the economy 7 is "talking" to it correctly to fire it up overnight (my off-peak tariff starts at about 23:30). Apparently I need to set the clock to the "correct time", but what time does that refer to? If I set it to, say, the time now (23:45ish), then that's only the correct time right now (it doesn't move)...? So tomorrow at 9am it would be "wrong" as it would still say 23:45? Am I missing something simple here?

(Yes, I know the knob looks odd, an electrician was here recently and has inspected it)

Thanks in advance!

 

Ildhund

mjtf24 said:

I need to set the clock to the "correct time", but what time does that refer to? If I set it to, say, the time now (23:45ish), then that's only the correct time right now (it doesn't move)...?  

I have a similar time switch, except that mine has the clockface on the rotating bit, so a mark on the case indicates the time now. With your stationary clockface, it looks like it's the pointer currently at around 11:00 that tells the time. If it's now 23:45, the scorched knob should be turned about 180º so that the pointer indicates almost 12 midnight. Of course, since it's a clock, it should both tick (actually more like a buzz) and rotate as time passes, but it needs mains power to do so. It will only rotate when the main switch above is on. If 'it doesn't move', it's broken.

Your meter should see to powering the lower heating element only during offpeak hours, and you may be able to hear it firing up, a bit like switching the kettle on. The thermostat will normally switch it off again long before the offpeak period ends.

I would expect your E7 offpeak times to shift by an hour at the end of British Summertime on 26 October, but check with your supplier.

MyRealNameToo

They dont communicate, thats the problem. Ideally your lower element is wired to a different circuit which is only live when in the E7 which makes life easier and cheaper if things go wrong. 

This seems to be a controller made by Pactrol, lots of people ask about it. 

Frozen_up_north

E7 switching is normally controlled by the meter, which will turn on a relay to switch a separate circuit wired to the immersion heater and storage heaters.

The usual installation included an override timer to boost the hot water with an element at the top of the water tank, this was on the ordinary “24 hour” wiring, which could be used to provide a limited amount of hot water if the hot water tank was cold and you didn’t want to wait overnight for hot water.

Ordinarily you would use the boost, is that what the timer in the image does?

QrizB

If I set it to, say, the time now (23:45ish), then that's only the correct time right now (it doesn't move)...? So tomorrow at 9am it would be "wrong" as it would still say 23:45? Am I missing something simple here?

As I understand things, the knob is connected to a timer and should rotate so the arrow is always pointing at the correct time, more or less.

If the knob doesn't rotate, the timer is probably knackered and the entire controller needs replacing. There are various models on the market with varying prices and capabilities. Fitting one is a relatively simple DIY job or something your electrician will easily be able to do.

WiserMiser

You seem to have two problems here.  Firstly, it's a very old and primitive motorised switch.  That's a hostage to fortune because a power cut (of which you may be unaware) will make it switch at the wrong times, so you'll find yourself heating your water at expensive day rates until you correct it. Similarly, they can get mechanically stuck.

Secondly, having a timer is a bit of a bodge because ideally you should operate the immersion heater from a circuit that's switched by the meter.  That's the only way to be certain you're heating using the cheap rate.  What the E7 times are supposed to be is irrelevant, it doesn't matter what your supplier tells you or what times apply in your region, all that counts is what your meter does.  If those times go out of kilter then it can cost your dearly.

That's the gloom and doom bit over, so here's the solution.  Make sure you have a 5-terminal meter, or a 4-terminal one with a contactor (typically a big black box that may get slightly warm); if you have storage heaters that's probably the case.  You then need to check the hot tank.  The usual arrangement is that there are two heaters.  The lower one should be on an E7 circuit switched by the meter (switched outlet left on) and overnight it gives you a full tank of hot water.  The upper heater is left switched off at the outlet and should be used only if you've run out of hot water during the day and need a day rate boost.  Best to have a timer that switches off after an hour or two to eliminate the risk of leaving it on by accident.

However, it sounds like you're using a 24h supply and relying on a timer to mimic the E7 times.

If you don't want to install an E7 switched circuit then you can fit a modern electronic timer.  To make sure you get the switching times correct, make sure at least one E7 outlet in an easily visible location has a neon indicator.  Remember that some areas have split E7 times, e.g. 2330 - 0130 and 0330 - 0730 GMT.