Scalding/dangerous hot water from immersion heater

Ivrytwr3

We moved into our new home yesterday (1999 build) and found there was no hot water. In the end we contacted the previous owners who informed us the heating is ran by the boiler (working fine) and the hot water is ran by the immersion heater which they left swotched constantly on.

We turned on the immersion heater (top part, as there is a top switch and bottom switch). A short time later we had hot water - yey!

However, at 2am, there was loud bubbling noises coming from the tank and the loft. I immediately turned off the immersion heater and found:

1. Pipe coming from top of immersion too hot to touch.

2. In loft the tank was bubbling like a boiling kettle and steam was coming from it.

3. When i turned on the hot water, it was scalding hot - no kidding, i couldn't touch it (you could have made a cup of tea with the water!)

I drained off some of the water through the taps and fortunatley we are all still alive this morning. I cannot find a thermostat anywhere, so can anyone advise what has happened? Do we need to get an engineer out?

(sorry for questions, but previous owner has not left any instruction manuals for system!)

Here are some pics of the system:

Canucklehead

Hi.


Immersion heater thermostat failed to 'unsafe'
You could try swapping the bottom for the top one until you get a new one with an overheat cutout on it.
They are fitted into a dry pocket so no need to turn any water off .
Obviously you will need to turn off the electric. (at the the fuse board end would be safer than the switch in the cupboard.)

The stat is under the round cover on the immersion. A small nut or screw holds the cover on. All will be revealed. Turn off power!

GSR.

1984ReturnsForReal_2

See the 2 wires going on to the boiler?

They are attached to to immersion heaters.

Under the round covers which are done up by screws there are thermostats.

One of them has failed/set to high/or both failed/set to high.

When all the electric is off for the house at the main consumers unit (I cant see a switch for it there) undo the covered with a screwdriver (should be one screw) and look at the settings on the thermostat. There is a wire going in & a wire going out & a little screw on top with some numbers around it. Turn the top one to about 65 and the bottom one to about 40.

They should both switch off at around these temperatures.

Then get someone to fit a timer controlling both thermostats that has a manual override.

And a strap on thermostat set at 70 & put on the top wouldn't go amiss to power off the whole lot should anything else fail & leave you with a melted tank in your loft and boiling water over your kids beds.

baldelectrician

Have a new thermostat fitted - the new ones come with 2 cut outs (one normal and one set higher for saftey)

The new stats are dear (the old ones cost a < £5 the new ones are >£10-£14). There isn't really an option as the dearer ones are alot safer

See HERE

The ones I use a from my wholesalers and are Howden ones (I use them as they are better and I get no problems). I don't know about other makes.

Ivrytwr3

ok, i've took the thermostats out and now have 2 x BT7 thermostats. On the net i have found these:

http://www.theelectricalcompany.co.uk/search.php?xSearch=bt7

Are these OK to use? Or can anyone recommend a better one?

Also, when i took them out, there were 2 wires going into the thermostats, 1 white, 1 grey. When replacing the thermostats does it matter what goes where? ie is it like a 3 pin plug, live, neutral etc?)

Ivrytwr3

no one? i'm stuck now then; lol!

closed

Get a quote to convert it to gas heated water?

gas4you

The wires into the thermostat are both live. One side from the external wire, the other from the stat to the element.

The neutral is connected to tha seperate contact in front of the stat and the earth to the side.

Thermostats should now have an overheat cut out as standard, to prevent what you have had from happening.

Canucklehead

Hi,

Take the stat to any plumbers or electrical merchant and get a new one. It will come with an overheat cutout as standard.

It doesn't matter what wire goes where ,but you will find the white wire from the terminal post will be too short to go in one terminal and relaxed to the other terminal.IYSWIM.

GSR.


PS Get some quotes for converting to gas h/w though;)
Edit
Like buses they all come at once.

keystone

What do the instructions say?

Are the terminals marked on the old ones?

Do markings on the terminals of the new ones correspond?

Cheers

Ivrytwr3

only ordered the parts today should be here in a few days.