Horstmann electric water heater question

[graemefaulkner]

I had a horstmann ecomomy off peak timer box for a immersion heater which although appeared to be working, the element never worked. After making sure it wasnt the element i bought a new timer box (Horstmann Electric 7), installed it following the instructions and it is working great.

I have one question regarding the wiring that wasnt clear in the instructions. I have an off peak circuit and a normal circuit but there is only connector for one power source. As the original box was wired with both circuits connected to the same live/neutral connectors i have done the same.

Now i know how it is wired I am concerned that as the normal circuit is live all the time, there isnt any point having the off peak circuit connected as the live is always on and i cant stop the unit drawing power from both circuits. Also do i need to worry about any power drain on the normal circuit when the off peak isnt live during the day?

Thanks

 

[seco services]

1. live power
2. neutral
3. heater neutrals.
4. boost element live.
5. off peak element live.

don't put all lives in terminal 1.

 

[Gaz the Sparky]

The horstman E7 time clock is designed to work with one supply.
it is supposed to be connected to the 24 hour supply because the clock inside swiches the heater on when its the economany 7 period which is usually between 1am and 7am (roughly speaking)

you then have the boost button on the front of the unit that switches the heater on for an hour to just top up the tank with warm water whenever you require.

it sounds like you have got the old system where two supplys where wired to the tank one was the 24 hour supply and the other was the off peak supply.

you should make safe the off peak supply by disconnecting it from the off peak fuse board and just use the 24 hour supply to power the clock because as you say the power will back feed when the off peak supply switches on.

so as stated it should be connected like
1. live supply in from 24 hour supply
2. neutral supply in from 24 hour supply
3.heater neutrals
4. boost element live (which is the top element on the tank if you have got two heaters )
5. off peak element live (which is the bottom element on the tank if you got two heaters)

if you have have one immersion heater on the tank then terminal 4 and 5 should be linked together and the live to the heater should go into terminal 4 or 5 with the link it doesn't really matter which one because they are both linked together

hope that helps
G.T.S

 

[graemefaulkner]

thanks for the clarification. I will disconnect the off peak feed and just run it on the main supply. It only needs to be on for an hour to warm up anyway so the benefits of cheaper electricity are much less than with the storage heaters.

 

[Aqua Marina]

I

if you have have one immersion heater on the tank then terminal 4 and 5 should be linked together and the live to the heater should go into terminal 4 or 5 with the link it doesn't really matter which one because they are both linked together

Hi thanks,
I get that it doesn't matter which live terminal is used (4 or 5) for the live going the out of the unit to the heater.
But then to link terminals 4 and 5 in the box — exactly how?
I assume that would be done by cutting off a small separate piece of Brown (live) wire and inserting one end into terminal 4 and one into terminal 5 to then form a small 'n' shape to link them together?

Read more: https://www.diynot.com/diy/threads/horstmann-electric-water-heater-question.212858/#ixzz6tHbntbvC

 

[EFLImpudence]

I assume that would be done by cutting off a small separate piece of Brown (live) wire and inserting one end into terminal 4 and one into terminal 5 to then form a small 'n' shape to link them together?

Yes, that's right.

You will probably have to form the 'n' shape first.

 

[Aqua Marina]

Yes, that's right.

You will probably have to form the 'n' shape first.

Hey, thanks for the clarification on exactly how to link the two terminals.

 

[ericmark]

Economy 7 is a tariff not a system. In the early days we had a white meter and the off peak and on peak was an independent supply, however that stopped on running washing machines on the off peak, so the latter system had a single supply and every thing in the house used off peak during the allotted time. It depends on which system you have as to how wired, and seem to remember being told there were versions only now used in Scotland, so answers from out of Scotland may well be wrong.

 

[Aqua Marina]

Yes, E7 is just a tariff. I have just a simple set up of a single element going into the boiler, and the whole property just goes over to cheap electric at night.
I just bought this timer to switch on the element during the night time economy hours only.
The instructions say that Terminal 4 is the 'Live Out' for the old daytime 'Boost tariff' and that Terminal 5 just the 'Live Out' feeds the the Off-Peak lower down element in the boiler (if indeed you have two elements) — but I don't have either of these.
The instructions say to 'link up terminals 4 and 5' if you just have a single element, yet I don't really understand why I have to do this — been as I don't have either the two elements in the boiler— or the old boost tariff.

 

[Aqua Marina]

Unless I got it wrong and the Terminal 4 'Live Out' Boost — is not for the old Daytime 'Boost tariff' but instead just a simple Boost or 'override' for any programmed time — which I've previously set the timer to?

 

[ericmark]

With two immersion heaters the boost is only supplied to the short or top immersion heater so whole tank not heated, with a single immersion direct in tank as said 4 and 5 are linked as other wise only boost or only over night will work, and it will take a long time to heat whole tank, with an external immersion heater with the Willis system then you get hot water within minutes of turning on, but only the thick Irish seem to have worked out how to use this system!!!

Maybe since there does seem to be a cultural link between Scotland and Ulster the Willis system may be used? Not seen it used in Wales, and not sure I would want to give it a try using a plumber who does not understand it?

I think the Willis system of heating from the top down is really good,

they say

A Willis Immersion heats approximately 4.5 litres of water to a high temperature every 5 minutes, so if one can decide before switching on how much water is required the pre-heating time can be calculated as follows:

• 4.5 litres for hand-washing, baby’s bath, shaving, breakfast dishes etc. = Pre-heat for 5 minutes
• 9 litres required for washing-up dinner dishes, medium sized clothes wash = Pre-heat for 10 minutes
• 9–14 litres required for a shower = Pre-heat for 10/15 minutes
• 54 litres required for a bath = Pre-heat for 1 hour

• Clearly quoted from a supplier in Northern Ireland, in fact Londonderry.

Using that system you would clearly want boost times of 5, 10, 15 minutes and an hour, so would not want the Horstmann timer.

 

[EFLImpudence]

The instructions say to 'link up terminals 4 and 5' if you just have a single element, yet I don't really understand why I have to do this — been as I don't have either the two elements in the boiler— or the old boost tariff.

The timer is for single or double element tanks.

As you only have one, the link is necessary.


You could of course have the immersion heater on during the day by altering the timer itself.

The so-called boost function allows you to turn it on without altering the timer - and switches the boost off after an hour or two in case you forget.

 

[Aqua Marina]

EFLImpudence
Expert clarification, succinctly put. Thanks again.