25A rated timer for electric boiler

[a-z electrics]

Hi guys,
I have a customer asking for a timer/programmer to be fitted to an electric boiler (Aztec 6kw by Trianco, Sheffield). It only has an isolating switch at the moment and presumably an internal stat. This is to allow some control over the time its powered up instead of on all the time cycling at high temperature. It also heats radiators for the central heating.

Most timers I have come across are rated at 13A, this one needs to be at 25A, I have a photo of the rating plate.

Anyone any ideas/done something similar? Is it a good idea in the first place? seems reasonable to me as most gas boilers have programmers.

Many thanks..

 

[SKY]

Can you not set it up so that a 13a timer switches on a relay feeding the water heater?

I have done this before using a small adaptable box with a din rail inside.

 

[Marvo]

I'm not sure if it's a good idea or a bad idea and you might find a 25A timer in the RS or Farnell range but I imagine it will be costly. I would just install a small DIN mount contactor like this one to do the switching of the load and use an off-the-shelf cheapie 6 or 10Amp rated timer to control the contactor.

Edit Pretty much what sky suggested.

 

[jaydee81]

install a controlls circuit and use central heating programmer and connect it to boiler sw terminals on right hand side of unit check out trianco.co.uk for electric boiler manual hope this helps

 

[COSMICSUN]

HI, COSMICSUN here. iam a first timer on here. I worked with industrial boilers in the past. I would also recommend a relay as sky advises, it is very easy to do, although one thing to mention is that you may need something to suppress the spark that gets created depending on the initaial current being consumed on start up. a capacitor has worked for me in the past. it may seem a bit ott but it prolongs the life of the relay stops any arcing and you can walk away without any worries your coming back.. kind regards COSMICSUN

 

[bugsy]

timer and contactor

 

[jaydee81]

aztec 6kw is a electric flow boiler it heats a cylinder for water and rads are you saying you have no controls fitted should be controlled same as gas or oil boiler using y or s plan with programmer cylinder stat and room thermostat

 

[a-z electrics]

ok, learning something new here.... never had dealings with contactors / relays before now....so a contactor is like a switch, controlled by a smaller current to switch a larger current, is that right? (always wondered what they were!)
I have looked thru a catalog and seen 25A contactors, mcb-like, for about £20; so I just fit this in a small din rail box with the 25A input and outputs. How does the timer get connected to do the switching? cheers..

 

[COSMICSUN]

HI A-Z. the timer output gets connected to the coil on the relay. depending on if the output is either one pole or two, ie one pole is just a live feed two pole is both live and neutral. you will need a 240v supply to your coil on your contacter. a neutral and a live. ie once the timer is activated it gives out a feed to the coil on your contacter. if it is only a live feed you need to wire up a permanent neutral link to your coil from the supply side of your timer. so then it act like a single pole switch. hope you understand it is so easy when you see it in your head, typing it out to explain is different. by the way if your timer only give out a 12 or 24 volt supply your coil needs to be 12 or 24volt rated. best regards good luck COSMICSUN

 

[a-z electrics]

Havent been to the premises yet - there is a cylinder stat apparently but no room stat, hence their request for a timer.. maybe your suggestion to wire in a programmer would be best solution, I checked out the trianco manual. Thnx.

 

[tlangdon12]

A - Z Electrics has now made it as far as C. (for Contactor)

(Sorry A-Z, couldn't resist.)

 

[a-z electrics]

Thats ok tlangdon12, thats about right.. have finally sussed out that all he needs is a room stat + timer/programmer. For some reason the water heating is done separately by immersion!!