Unvented immersion elements

[pertinky]

Morning guys,

We lost our lower element over the weekend, but the boost was working. However, this has incidentally stopped working too this morning.

The system is only a year old, but I know elements failing is quite a common occurrence; I was surprised both would go so quickly. The boost almost never gets used to be fair.

Before I call out the installer to replace the elements, is there anything I can do to check this is working from an electrical point of view?

I'm using a Horsmann 7 quartz timer, to which power is fine. I have two fused switches in the cupboard so I'm assuming one is for the unit. And the other is for BOTH elements?

 

[Tibbot]

Check the immersion overheat safety cut out stats haven't operated. They can be reset. Download instructions for your make to identify where they are (usually on the control stat, under immersion cover). To check timer, make sure 240V arrive at live on the immersions when calling for heat.

 

[Agile]

Normally there is a separate fused spur for each element.

They can be liable to nuisance trips of the overheat part. This is usually because they have been set higher than the 60 C recommended. Not helped when they have become lime scaled up.

Many users don't take advantage of having the upper element changed when the lower one is replaced which is good common sense and only costs about £25 extra in most cases.

Also using the correct type of element has a significant effect on the expected lifetime.

Tony

 

[Madrab]

You can also check the resistance of the element to confirm if it has failed, if you are familiar with resistance testing with a muti-meter. If there is zero resistance the element has gone.
Just remember to isolate from the supply before testing.

 

[ianmcd]

yes it does sound like the o/heat stats have tripped and can be reset, but you have received the correct advice if they have both tripped then get both thermostats changed at the same time it will work out cheaper in the end

 

[pertinky]

Cheers for the info guys!

Turns out the top element is OK - i thought the boost programme (the timer rather than just pressing the button for an hr) ran on upper element - i ran it this evening and i've got some hot water.

Sounds like I can use this as a workaround until I can get my hands on a multimeter on the weekend and have a look if the thermal cut off needs resetting.

 

[ianmcd]

you dont need a multi-meter, just isolate the power and remove the cover , the O/Heat cut out will have a small button on it and if it clicks when pressed then you have re-set it, if it doesnt click then it hasent operated

 

[pertinky]

I took the cover off, but I couldn't see anything that resembles a thermal cut off!

Its a Gledhill slimline.

Also, there seems to be a very small amount of water escaping

 

[Madrab]

Post a clear pic of the element with its cover off pertinky. Unfortunately, the make of the cylinder doesn't tell us what immersion element is in it.

Using a multimeter to check the element resistance is a quick way to find out whether it has gone or not and if it needs to be replaced.

 

[Agile]

The thermostat pocket often leaks.

Its good to check these units when cold and to remove the stat from the pocket to see if there is any leakage.

The element AND the thermostat pocket should both be Incaloy if you want to get the maximum life and avoid corrosion and leakage.

Tony

 

[pertinky]

Untitled

• pertinky
• 8 Dec 2013
• 1

Here you go!

 

[Agile]

Where is water leaking?

That one does not seem to have any o/h stat.

They have normally had the o/h device for at least 2-3 years.

Do you think it was "old stock" ?

Tony

 

[pertinky]

Its absolutely minimal, but definitely a little bit wet at the bottom of the element.

Well, its a year old from Plumbnation. So I'd have expected not; but ultimately you never know...

 

[ianmcd]

It looks as though someone in the past may have inadverently replaced your thermostat with a standard one as unvented elements must have some form of thermal cut out in case the stat fails in the on position, I have seen unvented systems where there is one master O/H stat that cuts power to all immersion heaters, can you post pics on all the equipment attached to the cylinder or tell us the specific make and model of the cylinder

 

[pertinky]

Gledhill Stainless Lite Slimline D210-SL Direct Stainless Steel Unvented Hot Water Cylinder 210 Litre

All I have in the cupboard is 2 spurs and the Horsmann timer.