heating element problems with economy 7

[Deleted member 112031]

I have an economy 7 boiler which has two temperature controlled heating elements. After 15 years they were replaced as they had started to heat inefficiently. Unsurprisingly they were covered in limescale.

I replaced them with new elements. The off peak element was placed on just over 50 degrees but kept on needing a reset so it was reduced to 45 degrees. After 6 months it blew up and the element needed replacing. It had split open and the fuse also blew.

I replaced both the elements with chrome elements. Same thing has happened again with the off peak element.

I am puzzled as to what is causing this and I am loathe to spend hundreds of pounds replacing them again.

I have one theory. My eco 7 off peak stays on all over the weekend. (Pls don't ask me why.) I think maybe that the element doesn't like staying on that much though I don't know how often elements check the temperature. I think that maybe the temperature control is malfunctioning meaning it heats up beyond what the temp is set at and then needs resetting as in the days before they blow it needs resetting a lot.

During the recent heat wave I hardly had it on and it was fine. As soon as it turned cold and had to some significant work it blew.

What can I do? Is it the electrics that are causing the problem and if so what action do I need to take.

The previous elements lasted for 15 years and worked great for 14.5 years without issue so I am puzzled why these new elements are breaking so quickly.

Thanks for any help or suggestions!

Rich

 

[Spoon]

Do you not get 12 months warranty with the elements?

 

[Deleted member 112031]

The plumber who installed them despite being a local, reputable firm has not been helpful in that regard. He said it would be hard to prove that the element was at fault.

Even if I got a refund of my £60 for the broken element it doesn't get me anywhere nearer to solving this problem.

It is strange that two consecutive elements have blown which would indicate it was not the element at fault. Or is it common that they blow like this?

 

[Taylortwocities]

My eco 7 off peak stays on all over the weekend.

It doesn't. There may be power to the element, but there is also a thermostat that controls the temperature. Once the water is heated (to whatever) the thermostat turns off the element, until the temperature drops.
When the element was changed, it would have been the best thing to chnage the thermostat as well.

 

[SJD]

Are you sure the thermostat is the correct length and type. I've come across the wrong length fitted, perhaps because that is what the plumber happened to have on the van, so it is not sensing the temperature in the correct place.

 

[Marvo]

The most common cause of an element blowing open and splitting is dry running ie no water and excessive limescale build-up. You can pretty much rule out limescale if the plumber cleaned out the cylinder when the elements were replaced not long ago.

I'd also be wary of the quality of new items especially if the plumber is being unhelpful regarding a warranty claim, there's a lot of cheap rubbish on the market that's not fit for purpose. Usually a reputable wholesaler will happily entertain a warranty claim for a respectable brand name item if it was installed by a professional licensed plumber so I wouldn't accept him being 'unhelpful' if I were you.

 

[GBDamo]

I have an economy 7 boiler which has two temperature controlled heating elements. After 15 years they were replaced as they had started to heat inefficiently. Unsurprisingly they were covered in limescale.

I replaced them with new elements. The off peak element was placed on just over 50 degrees but kept on needing a reset so it was reduced to 45 degrees. After 6 months it blew up and the element needed replacing. It had split open and the fuse also blew.

I replaced both the elements with chrome elements. Same thing has happened again with the off peak element.

I am puzzled as to what is causing this and I am loathe to spend hundreds of pounds replacing them again.

I have one theory. My eco 7 off peak stays on all over the weekend. (Pls don't ask me why.) I think maybe that the element doesn't like staying on that much though I don't know how often elements check the temperature. I think that maybe the temperature control is malfunctioning meaning it heats up beyond what the temp is set at and then needs resetting as in the days before they blow it needs resetting a lot.

During the recent heat wave I hardly had it on and it was fine. As soon as it turned cold and had to some significant work it blew.

What can I do? Is it the electrics that are causing the problem and if so what action do I need to take.

The previous elements lasted for 15 years and worked great for 14.5 years without issue so I am puzzled why these new elements are breaking so quickly.

Thanks for any help or suggestions!

Rich

Does/did your system have a sacrificial anode(SA)? In certain water areas it can help enormously with corrosion.

The originals may have been high quality Incaloy or similar, very resistant to corrosion, coupled with a SA to give the long life.

I'm guessing the SA has corroded away, the new elements are cheapo (although you may have thought you were buying quality) and are only lasting a year.

Google galvanic corrosion and and sacrificial anodes.

 

[marconi]

Could you provide details of the boiler - make,model number?

 

[Deleted member 112031]

Thanks for all your helpful replies.

I agree in retrospect it is suspicious that the plumber wouldn't provide me with the paperwork for the new elements. I asked numerous times before and after the fitting. I am writing formally to him.

The only thermostat in the system is that which is contained within the element. There is no separate thermostat.

I don't believe the system has a sacrificial anode(SA) nor were the original elements high quality Incaloy or similar. This is a shared ownership housing association block and everything was put together as cheaply as possible.

The first set of replacement elements looked identical to the originals. When the off peak replacement element split it wasn't covered in limescale unlike the originals. The chrome elements that replaced the first lot of replacements were slightly longer.

The system is a kernel direct plumbing unit produce code: 3396 installed in 2000. I can provide photos if helpful.

I've spoken to more of my neighbours and one of them said they had a similar problem with elements splitting. That neighbour didn't have a particularly solution beyond replacing the broken ones.

Can anyone suggest a good quality element to use this time?

Some of my neighbours have changed their set up completely, getting rid of economy 7, and moving to a pressure system. (Sorry not sure of the right term.) That's also an option.

Thanks again for your insights and suggestions.

Rich

 

[Taylortwocities]

The only thermostat in the system is that which is contained within the element. There is no separate thermostat.

I have never, ever seen that.

Inside the immersion housing for the element (under the top cover) there is a separate, removeable thermostat. The stat can be changed without draining the tank.

Please post a photo of the immersion connections.