IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Timer for Econ7 immersion heater
Topic Summary: Can i place an additional clock
Created On: 08 July 2013 04:07 PM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 08 July 2013 04:07 PM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

Customer has a strange setup. He has a version of economy 7 where he gets cheaper electricity in the night and for a few hours in the day. However he wants to be able to reduce the number of hours that the water heater is used without simply turning the Immersion heater isolation switch to off.

He purchased a straightforward timer clock. Obviously this can't be used as the clock won't keep time when the low rate power is on.

Are there any clocks available that can have an alternative source of power to keep the clock running during "off" periods and allow switching to interrupt the power to the immersion heater during "on" periods? I've certainly never seen one.

Thanks
Jon
 08 July 2013 04:12 PM
User is offline View Users Profile Print this message



normcall

Posts: 8149
Joined: 15 January 2005

AFAIK, all time switches keep the clock going when the setting is off.
What you really want is a separate supply for the clock and volt free set of contacts. Sangamo do one and I expect many other manufacturers, but the 'sheds' won't have them due to cost. Then you need an uninterrupted supply (lighting circuit?)

-------------------------
Norman
 08 July 2013 04:21 PM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

Thanks Norm. I have an uninterrupted supply close by (boiler FCU fed from ring circuit). I'm a bit tight for space where it needs to go. I did suggest to the customer a contactor in an enclosure, but I'm not sure it will fit (or at least not the usual ones I fit for timed flood lights).

I'll look into your suggestion to see if I can find something more compact.

Jon
 08 July 2013 04:29 PM
User is online View Users Profile Print this message



AJJewsbury

Posts: 11585
Joined: 13 August 2003

Does the customer have a dual-rate meter or two separate meters for peak/off-peak? If one meter (which switches between different rates at different times - so the 24h supply is also charged at low rate at off peak times) then perhaps move the water heater circuit over to the 24h supply and rely on the new timer only to switch on during off-peak times. Not ideal (always a risk of the customer's time getting unsynchronised with the suppliers), but might save the hassle of adding a contactor.
- Andy.
 08 July 2013 05:16 PM
User is offline View Users Profile Print this message



broadgage

Posts: 1311
Joined: 07 August 2007

Most cheaper timeswitches need a continous supply into the clock mechanism for it to keep time.
In cheaper basic timeswitches there is no simple way of seperating the clock supply from the supply that is to be switched.

Sangamo do indeed make a suitable time switch for this application, you need the "round pattern, 4 pin plug in timeswitch" These have 2 connections for the clock supply and two more ISOLATED connections for switching the load.

The three pin sort are not suitable, they are simply a much better qaulity version of the cheap ones with an internal connection between clock and load circuits.

Another option would any cheap timeswitch of your choice connected to a permanently live circuit, with the switched output being used to control a suitable relay or contactor in series with the load.
 08 July 2013 05:37 PM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

Thanks Broadgage. I checked out the Sagamo website and saw the timer you suggested. I proposed your solution in last part of post to the customer but as space is limited and the contactors / enclosures are a bit large and ugly he was less than keen.

Will probably go with the Sagamo time clock if he will accept the cost.

Thanks
John
 08 July 2013 06:54 PM
User is offline View Users Profile Print this message


Avatar for M.Joshi.
M.Joshi

Posts: 212
Joined: 10 January 2003

I believe the Time-Guard series retain the settings and time when power is lost:

http://www.timeguard.com/produ...ion-heater-controllers

-------------------------
M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!
 08 July 2013 08:06 PM
User is offline View Users Profile Print this message



maltrefor

Posts: 121
Joined: 01 November 2009

http://horstmann.co.uk/downloa...ating/Electronic7.pdf




This unit can be set for up to 3 off peak periods in 24 hours.
 08 July 2013 08:37 PM
User is offline View Users Profile Print this message



peteTLM

Posts: 3187
Joined: 31 March 2005

its called ecomony 10 tariff

-------------------------
----------------------------------------
Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 09 July 2013 08:27 AM
User is offline View Users Profile Print this message



broadgage

Posts: 1311
Joined: 07 August 2007

Originally posted by: M.Joshi

I believe the Time-Guard series retain the settings and time when power is lost:



http://www.timeguard.com/produ...ion-heater-controllers


Yes, they retain the settings in case of the odd power cut, this being done by a very small internal battery. This feature is intended for the odd breakdown, I very much doubt that it would work for long with power only present for 14 hours out of 24, long term.
 09 July 2013 12:16 PM
User is offline View Users Profile Print this message



kshrimpton

Posts: 11
Joined: 15 February 2007

I doubt you'd have a problem with either of the above mentioned -Horstmann with a quoted 2 year battery or Timeguard with 720hrs . The Horstmann seems designed for your application.

KS
 09 July 2013 12:47 PM
User is offline View Users Profile Print this message


Avatar for M.Joshi.
M.Joshi

Posts: 212
Joined: 10 January 2003

The only reason I mentioned the Timeguard over the Horstmann is because the Horstmann one is considerably more expensive. The Horstmann is probably the ideal solution though.

-------------------------
M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!
 09 July 2013 12:47 PM
User is online View Users Profile Print this message



AJJewsbury

Posts: 11585
Joined: 13 August 2003

quoted 2 year battery

but doesn't appear to be rechargable - so on an E10 or similar scheme you might expect the unit to fail after less than 3 and a half years.
- Andy.
 09 July 2013 01:57 PM
User is offline View Users Profile Print this message



Pacific

Posts: 596
Joined: 29 January 2005

Originally posted by: peteTLM

its called ecomony 10 tariff


Does E10 work like that ie only energising heaters and not switching over the whole house to off peak. I was under the impression that it was an extended E7
 09 July 2013 03:40 PM
User is offline View Users Profile Print this message


Avatar for M.Joshi.
M.Joshi

Posts: 212
Joined: 10 January 2003

Explanation of Economy 10:

http://www.ukpower.co.uk/home_energy/economy_10/

-------------------------
M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!
 09 July 2013 03:44 PM
User is offline View Users Profile Print this message



Pacific

Posts: 596
Joined: 29 January 2005

Originally posted by: M.Joshi

Explanation of Economy 10:



http://www.ukpower.co.uk/home_energy/economy_10/


So is it like E7, not clear from the explanation whether the whole house is on E10, anyway the system described by the OP sounds like an old tariff with separate meters, my in laws still have one and I wired a timer for the immersion for them powered from the lighting circuit

 09 July 2013 11:44 PM
User is offline View Users Profile Print this message



alancapon

Posts: 5790
Joined: 27 December 2005

My understanding is that Economy 10 is like an Economy 7, but with an afternoon and evening boost. The modern electronic meters have a Radio Tele-Switch built in, rather than as a separate device but usually do not have sufficient space for an internal contactor. The contactor to switch the off-peak supply is usually owned by the customer, and operated by a switched neutral from the meter. The phase to the contactor comes off the load side of the electricity meter, using a suitable sized fuse.

Regards,

Alan.
 10 July 2013 06:10 AM
User is offline View Users Profile Print this message



Jaymack

Posts: 4699
Joined: 07 April 2004

Originally posted by: JZN
Are there any clocks available that can have an alternative source of power to keep the clock running during "off" periods and allow switching to interrupt the power to the immersion heater during "on" periods? I've certainly never seen one.

Greenbrook Kingshield T105-C is an electronic 7 day programmable timer.

Regards
 10 July 2013 07:16 AM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

It's not the whole house that switches to off/on peak rates, just the water heater and a couple of electric heater circuits. The cable to the immersion is therefore effectively dead. I've used the horstman timers before but only where the supply is always live and it's just the tariff that changes. I'm sure the back up batteries in these are not meant to cope with keeping the clock going most of the day while the supply is dead during off peak times.

Will look into the Greenbrook option Jaymak.

Thanks for the replies

John
 10 July 2013 09:09 AM
User is offline View Users Profile Print this message


Avatar for potential.
potential

Posts: 1278
Joined: 01 February 2007

Originally posted by: M.Joshi

Explanation of Economy 10:



http://www.ukpower.co.uk/home_energy/economy_10/

For information, I have an old Economy 10 tariff in my house.
It dates from the 60s, has one (white) meter with dual dial, a separate clockwork time switch, all the house is on the tariff and the meter dials are switched from 9pm to 7am GMT.
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.