Immersion Heater fault

[lim88]

I have an immersion heater controlled by an horstmann economy 7 Quartz timeswitch that will not heat the tank. The whole heater unit was replaced only a few weeks ago, and I replaced the timeswitch like for like in january last year and the thermostat had already been replaced 3 times in the last few days, before I even looked at it.
I have tested everywhere I can. When the timeswitch operates I have power on the incoming and out going terminals in the timeswitch, on the incoming and out going at the thermostat and at the element itself. The only possible reason I can see for the fault at the moment is possibly the element playing up, even though it was working perfect after they installed it.

Like I said I have tested at every accessible point and all seems fine. Is there something obvious I am missing?
I would be great full if anyone has any idea or advice on what else I can do to solve this.

Many thanks

 

[Deleted member 9648]

Test across the element terminals with your ohmeter,you should get a reading of around 17-18 ohms (off the top of my head). If so and there is 230v on the element when switched on it will heat up. If you get open circuit the element has failed.

 

[billy110]

Some elements have a thermal trip on them, usually a little black plastic nob which doesn't always look obvious when it's tripped. As wirepuller said the element continuity is usually about 18 ohms but make sure you are getting continuity accross all the element components.

 

[lim88]

Thanks for the help wirepuller and billy110.

Luckily for the customer they are on holiday at the moment, I'm getting a spare key early next week so I will check these things and hopefully I can solve it for them before they get back.

I will let you know how it goes.

 

[Hawk81]

you can also clamp the element to see if it is drawing a load.

 

[mogga]

first thing to check is that the element is getting power no point checking the element till you establish it has a supply Q7 controler may be at fault also check that the BOOST element is connected at the TOP of tank and overnight element is at the bottom other way round and you will only heat top of tank overnight

 

[lim88]

Thanks I will clamp it too, to make sure.

yes the element is definitely getting power, and the boost element is not in use. I mentioned about the boost element not being used when I replaced the Q7 controller 17 months ago, but they never use the boost and don't want it connected.

 

[jackdor]

i had a customer who had a coal fire with a back boiler that would heat up the water when fire was lit. only problem was that if the fire was on for a while it would operate the thermal trip on the heating element. so when they wanted to use it later i would not work.

 

[lim88]

The element was fine, it was just the thermal trip I obviously missed the little plastic knob in that dark little corner. I have to wonder if that was the problem with the old one the customer said they had already replaced.

Thanks for the help.

 

[davelerave]

you might need to fit a cylinder stat if a separate boiler is overheating the cylinder-as already said they can be troublessome

 

[Deleted member 9648]

you might need to fit a cylinder stat if a separate boiler is overheating the cylinder-as already said they can be troublessome

You cant fit a cylinder stat to a solid fuel boiler fed hot tank....generally the tank is fed by an uninterupted gravity feed which is the means by which excess heat from the boiler is lost. You cant switch off a solid fuel boiler like you can a gas/oil one.

 

[lim88]

There is no boiler anyway, only the immersion for hot water and night stores for heating

 

[davelerave]

You cant fit a cylinder stat to a solid fuel boiler fed hot tank....generally the tank is fed by an uninterupted gravity feed which is the means by which excess heat from the boiler is lost. You cant switch off a solid fuel boiler like you can a gas/oil one.

thanks i'm well aware of that-i didn't mention solid fuel boilers

 

[Deleted member 9648]

thanks i'm well aware of that-i didn't mention solid fuel boilers

Sorry if my post smacks of sucking eggs....I assumed you were referring to jackdors post which pointed out solid fuel boilers as potentially causing thermal trips to operate.

 

[davelerave]

i've seen it with oil boilers if memory serves -when a stat/mv isn't fitted