immersion heater and thermostat

[hothothot]

Having posted the below message and received answers that there might be a bad connection, I checked the wiring but couldn't see anything wrong. Nonetheless, I removed the thermostat and wired back in.

Unfortunately, after just half an hour of the heating being on, the water is still overheating. It appears the brand new thermostat is not cutting out the heat. Given that this is the second thermostat with the same problem, do you think that there is an issue elsewhere with the immersion? Maybe the element is faulty?

=============== original message =================
I bought a property recently with an immersion heater. The water was scolding. I tried to vary the thermostatic setting, but the temperature was always too hot to touch.

I visited the local plumbing shop who recommended that I change the thermostat. After changing the device, the temperature was still too high (factory setting was 65). I turned down the thermostat and immediately the temperature went down. However, this time is was just a tad too cool for my liking. So I turned up the thermostat a fraction. I went out for a couple of hours and when I got back there was the smell of burning. I sourced it to the immersion which I switched off. I took the immersion cap off and saw the inside was black and so were the wires although they have not burnt out.

 

[Agile]

Why are you apparently starting a new thread?

Its extremely unlikely that anything is faulty twice!

I would even wonder if its correctly wired or the stat set to the right temperature.

In any case current stats have an overheat device which cuts off when the temperature gets too hot.

It sounds to me as if there is something seriously wrong and that could be dangerous.

My advice would be to get professional help!

Tony

 

[twgas]

have you checked the temp with a thermometer, or are you just running water and testing with your hand?

 

[hothothot]

I didn't check the temperature with a thermometer but with my hands. The water was scolding.

This morning, I unwired the immersion thermostat which had clearly melted from the heat and was no longer functioning.

I took it to the plumbing shop where I bought it. After examining it, they said that it looked as if there were too many appliances running off the same circuit as the immersion which just overloaded.

I recalled that when the device went down the first time, all the appliances in the kitchen stopped working: fridge, freezer, dishwasher and oven; broadband router and phone also went down; there was no electric feed into to the toaster and kettle sockets although these appliances were not actually on. But I was using two computers off the same circuit and these also stopped working.

One of the two thermostats for the underfloor heating had also melted. I've since removed the device, terminated the wires with plastic blocks and sealed off the hole in the wall with a plastic plate.

I'm now going to seal off 4 of the 8 sockets in the kitchen and move the phone, router and computers to another part of the flat. I felt when I bought the property, there were too many sockets and it did cross my mind if all sockets and appliances were in use, then there might be an overload.

The plumbing shop advised me to install a brand new element (with cut out therm) just to be on the safe side even though the old element is still heating up. They pointed out that that there might even be a split in the element but obviously without seeing, they can't be sure.

What do you think about the above advise and the measures I've taken? Can you suggest anything else?

I will install the new element tomorrow so fingers crossed.

 

[Agile]

I took it to the plumbing shop where I bought it. After examining it, they said that it looked as if there were too many appliances running off the same circuit as the immersion which just overloaded.

That is total nonsense! But what should you expect? A competent electrician is hardly likely to take a sales assistant job!

You should measure the insulation resistance of the element ( over 1 Meg. ) and the element resistance which should be around 18 ohms.

Obviously I have not inspected your installation so I dont know whats wrong as I have not been able to test it.

I still question why you have apparently been using an illegal thermostat without an overheat trip.

Tony

 

[Softus]

I still question why you have apparently been using an illegal thermostat without an overheat trip.

Could you remind everyone which law is being broken when the alleged illegal thermostat is installed?

 

[Agile]

From the CIBSE's web site:-

Following the tragic death of a young mother earlier this year, the CIBSE Domestic Building Services Panel has called for the heating industry to be increasingly vigilant regarding safety in immersion heater installations.

The most important action is to ensure that any new or replacement immersion heaters fitted comply with the EN 60335-2-73:1996 standard which will be a legal requirement from April 2004.

This standard requires that the overheat thermostat cuts out with contacts open, is non-self resetting and operates independently of the water thermostat.

The recent death occurred when a faulty immersion heater thermostat failed, allowing the water in the plastic cold-water tank to eventually reach boiling point. During the night when the victim was asleep, the poorly-supported water tank bulged and flopped over. Hot water then poured through the ceiling onto the victim sleeping below.

As well as the safety of immersion heaters, the incident draws attention to the need to ensure that plastic cold-water tanks are provided with fully-supporting bases.

 

[Softus]

Could you remind everyone which law is being broken when the alleged illegal thermostat is installed?

 

[hothothot]

The plumber told me that the thermostat was with auto cut-out. But I don't understand why it failed to stop the water overheating. The wires were definitely connected. I triple checked them.

What I did notice when removing the thermostat was that the side of the plastic head had melted. When I popped it back into the immersion sleeve, I noticed that the plastic head was touching the metal immersion head. This is not so on the new element that I bought. Could it be that I had the wrong make or design of thermostat?

 

[Softus]

C ould you measure the depth of the thermostat pocket (with some curtain wire, or similar)?

Also, the length of all three rod thermostats?

 

[hothothot]

I've now replaced the who element with a new thermostat and the system now seems to be working.

I guess I'll never really know what the cause of the problem was but thank you everyone who offered advise.

 

[Softus]

I still question why you have apparently been using an illegal thermostat without an overheat trip.

Could you remind everyone which law is being broken when the alleged illegal thermostat is installed?

 

[Agile]

If you want legal advice, Softus, I suggest you consult your solicitor who will charge you about £300 p.h.

I only give free plumbing and heating advice on forums!

Tony

 

[Softus]

If you want legal advice, Softus, I suggest you consult your solicitor who will charge you about £300 p.h.

I didn't ask for, and I don't want, any legal advice.

I'll give you the benefit of the doubt and infer that you didn't understand my question, rather than the other possibility of you just evading it.

The issue is of you telling someone that their actions are illegal, without revealing which law was being broken, so I asked you which law you think it is.

If you don't know, then just say "I don't know".

 

[Agile]

If you want legal advice, Softus, I suggest you consult your solicitor who will charge you about £300 p.h.

I didn't ask for, and I don't want, any legal advice.

.............. so I asked you which law you think it is.

Asking about laws would be legal advice im most people's views!

Why dont you like to be called by your own name?

Tony

( Thats my real name! )