off peak immersion problems

[hairy g string]

hi .customer complained that her off peak water wasn't heating.its a ex b7 controler .boost worked fine on 24 supply.there is just 1 cable going to tank [1 elememnt] but off peak trips old wylex 15a push button mcb
sorry dont no the bs number.changed the b7 controller because it was 25 years old anyway.the off peak came on to give her a full tank of hot water and then next day trips.never tested element or cable because the boost works fine on a mem 16 a mcb.i am going to put in a 2 way consumer unit tomorrow for off peak.
surely it has to be that pop mcb that is faulty.has anyone else came across similar scenarios .thanks

 

[rattlehead85]

This sounds to me that you may have a problem with the off peak supply feeding the controller. If it works on boost supply but blows when it runs on the night supply the chances of the element being defective are minimal. I would firstly disconnect both supplies from the CU and controller and carry out proper i.r tests to clarify firstly your circuits feeding the unit are healthy.

 

[rattlehead85]

I wouldn't take anything by chance on council properties, tenants can't help but dabble and play with stuff they no nothing about!!

 

[davesparks]

That set up is not the norm, because that totally defeats the object of an off peak consumer unit.

It's pretty common around here. How does it defeat the object of it?

 

[rattlehead85]

That set up is not the norm, because that totally defeats the object of an off peak consumer unit.

You clearly have little to no previous knowledge of how this set up operates if you think is not normal. Thousands of local housing authority blocks used this set up and some to this day still use them.

 

[7029 dave]

You clearly have little to no previous knowledge of how this set up operates if you think is not normal. Thousands of local housing authority blocks used this set up and some to this day still use them.

Yeah if you say so, cool.

 

[rattlehead85]

Yeah if you say so, cool.

Well explain why you think it's not normal. I'm not being funny i'm just seeing where you may be going wrong that's all. Nobody knows everything mate.

 

[rattlehead85]

. this is the clock in question or similar

 

[7029 dave]

I am saying if the off peak is dedicated ie only live on off peak,one element, one flex, how is that going to work without linking both 24hrs and off peak cu's together.?

 

[davesparks]

I am saying if the off peak is dedicated ie only live on off peak,one element, one flex, how is that going to work without linking both 24hrs and off peak cu's together.?

It's just a changeover switch with a timer.

It's normal position is with the element connected to the off peak supply.
When the timer is activated it changed over to the 24hr supply for the time period then drops back to the off peak supply.

 

[rattlehead85]

I am saying if the off peak is dedicated ie only live on off peak,one element, one flex, how is that going to work without linking both 24hrs and off peak cu's together.?

The unit basically works as an either or switch. If the switch is in the off position the element draws no supply......
If you switch it to boost and turn the boost dial it uses the on peak circuit for the time you set the boost dial for......if you choose to switch to 'timed' supply the boost dial is rendered dead and the element becomes live when the off peak circuit becomes energised by the dno. All functions from one element, thats how it works matey.

 

[rattlehead85]

The clock 'davesparks' mentioned is a similar method of operating the element the only difference being that the boost unit has only two switch positions instead of three. Same outcome with only one element. [emoji106][emoji106]

 

[7029 dave]

It's just a changeover switch with a timer.

It's normal position is with the element connected to the off peak supply.
When the timer is activated it changed over to the 24hr supply for the time period then drops back to the off peak supply.

That makes sense, but an easier way would be to have the IH circuit on 24hrs, with E7 tariff, when off peak kicks in the whole installation goes over anyway, so change over switch/ clock not needed.

 

[Dave OCD]

That makes sense, but an easier way would be to have the IH circuit on 24hrs, with E7 tariff, when off peak kicks in the whole installation goes over anyway, so change over switch/ clock not needed.

Exactly Dave, but unless you want to stay up until midnight or 1 in the morning every night to switch it on you still need a timer.

 

[rattlehead85]

That makes sense, but an easier way would be to have the IH circuit on 24hrs, with E7 tariff, when off peak kicks in the whole installation goes over anyway, so change over switch/ clock not needed.

One problem with that one matey. You'd have to have the switch on all the time which would send your bill through the roof and knacker your thermostat inside the tank in next to no time with it kicking in and out all day. Alternatively you'd have to manually switch it on at night when the E7 kicks in.

 

[Dcf]

the E7 BX is the horstmann timer of choice for THTC installations .
It can be configured to either feed an off peak heater and boost heater or a single heater by putting links across 5+9 and 6+10.
make sure they are not mixed up as one is the live and the other the neutral!
I find them pretty reliable tbh as there is no moving parts to them unlike their E7 quartz cousins.
the off peak is switched by the radio telemeter at various parts of the day.
the boost is available 24 hr.
check the heater and thermostat first.look out for white powder in the bottom of the case a sure sign that the element is on its way out.
if ok check your controller is wired up correctly.the BX can get a bit congested with 10 terminals in it..
check your circuits after this.
these types of plug in mcb used to have a 3k rating if i mind right and if its had a short odds on its knacked.