Immersion timer wiring - 5 terminals?

[Lauraalgar]

Hi all,

I’m trying to update an old immersion timer (works only by switch, timer knackered) and confused by the fact it has 5 terminals…

There’s a fused switch connected to the existing timer meaning I have two sets of (old style) cables, not sure if one terminal in the new box ought to be unused or whether I’ve bought something unsuitable…

Any help greatly appreciated!

Laura

 

[Taylortwocities]

The box in the last photo is designed god use with a certain type of Economy 7 supply. Is that what you have?

 

[Lauraalgar]

Yes, we have economy 7

 

[Taylortwocities]

I guess the new box is a horstmann timer???. How many immersions do you have.?
If you have one follow the instructions. If you have two then follow the instructions…
This is the one heater version, what don’t you understand?

 

[Lauraalgar]

These are the instructions, assume both L & N are going in from the fused switch, but then haven’t a clue which two terminals the others would go to - seems immersion N would go into terminal 3 - but appears I’d need to choose between the boost and timer terminals for the immersion L which seems odd - unless I’m completely off the mark?

 

[Lauraalgar]

I guess the new box is a horstmann timer???. How many immersions do you have.?
If you have one follow the instructions. If you have two then follow the instructions…
This is the one heater version, what don’t you understand?
View attachment 321765

Ah - I was missing the bridge wire info, seems likely to be the case, no? Only getting used to smaller diy leccy tasks so a new one for me! Thanks for sharing.

 

[Taylortwocities]

Yes. For one immersion you need the link.
I’m hoping you were provided with instructions with the timer?

 

[Adam_151]

The reason there are two terminals is that in many instances there would be two separate immersion heaters, you'd have a lower one that you'd want to run on E7 during the night, and a boost one in the top which would only heat a part tank for if you ran out of hot water in the day.

Often you'd have a timed supply from a separate fuseboard for the bottom one, and just a switch for the top one.

For supplies where the whole instalaltion goes onto the E7 rate, you could just run one supply and use the local timer in one of these controllers, which would also allow boosting the top element from the same supply (making sure the lower one wasn't on at the time)

When you just have the one immersion heater, you can link the two switch lives together and have boost on the same element as the timed supply, though there are cheaper units to acheive this functionality with just one element

 

[Lauraalgar]

Thanks both, super grateful. We have one old immersion heater in our ramshackle place we bought last December! It can be used with the boiler but the rads have to run at the same time (don’t ask), either hooked up that way or also needs some attention (turning pipework valve from boiler manually to supply hot water only doesn’t warm anything). Anyway, in the short term it means we either burn through oil at an ungodly rate or utilise the immersion on E7 - at least until we replace the heating system next year.

Yes there’s instructions to set the timer, leaflet is pretty useless but shouldn’t be too hard!

L

 

[Lauraalgar]

Thanks all - ever grateful! L