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:

 

[ivrytwr3]

 

[gasmarc]

Do not switch it back on the thermostat has gone ,people have died before due to this

 

[ivrytwr3]

now i'm scared! Thanks for the swift reply!

 

[gasmarc]

no problem if the power is turned off its safe

 

[gasmarc]

there is a thermostat inside the cylinder that has packed up ,they cost about £20 max to buy a new immersion that comes with the resettable stat

 

[so-solar]

as above, but please please dont switch it back on. i have seen tanks melted and boiling water flowing through the ceiling all over somebodys bed, thank god they were not in it at the time.

 

[gasmarc]

well i think these was a case a year ago ,best not go down that road, ideally you could get a good sparky to replace the stat and it has to be resettable as this is the law now ,for the exact reason that could have happened,screwfix will do them I think good luck

 

[Billy Bob Bob]

yes a young child died trough a thermostat failing it caused a round plastic tank to fail thats why new stats now have thermal cut outs i am curious though you must have a way to have hot water of the boiler perhaps its gravity is there a time clock in the house

 

[ivrytwr3]

yes a young child died trough a thermostat failing it caused a round plastic tank to fail thats why new stats now have thermal cut outs i am curious though you must have a way to have hot water of the boiler perhaps its gravity is there a time clock in the house

Without the immersion switches on there is no hot water at all.

A time clock? In the airing cupboard is the timer, but this only appears to control the heating.

 

[GrahamM]

yes a young child died trough a thermostat failing it caused a round plastic tank to fail thats why new stats now have thermal cut outs i am curious though you must have a way to have hot water of the boiler perhaps its gravity is there a time clock in the house

Looks like it's a heating only boiler gas man. Does not appear to be any flow/return in the cylinder pick above.

 

[gasmarc]

yes i spotted that maybe they are on economy 7 or some cheap tariff ,I would change it over myself but maybe there is a reason why who knows

 

[ivrytwr3]

change it over to what? EON are coming out to change the meter soon.

(when i calle dthem i had to give 5 electric readings! they said a new meter will allow me to remain on my fixed tarrif and only have a day and night reading).

 

[Billy Bob Bob]

get it converted to fully pumped

 

[ivrytwr3]

hee hee, mate that means nothing to me! How much? who should do it? Why should i do it?

Next instalment......


at 2am, i switched off the top switch due to the problem. This morning we had no hot water. I then stitched on the bottom switch and a few hours later we have correct temperature hot water.

Should i leave the bottom one switched on and just use the top for quick bursts? Or do you think there is still a problem with the temperature control?

 

[TC.]

your cylinder is fitted with two immersion heaters, one at the bottom to heat up the cylinder at night when the leccy tarriff is cheap and the one at the top to provide hot water on demand, well kind of!

Do not under any circumstances turn the top one one not even for a nanosecond, it is dangerous and should not be used. It needs replacing before you can consider turning on the top part of cylinder. There is a problem with the termostat inside the top immersion heater, causing it to boil the water inside the cylinder and i bet its boiling out into your cold water storage tank. As it should.

Just in case i didnt mention it, get it replaced!!

 

[TC.]

if you go careful and ration your hot water usage, you can use the lower one to heat up your cylinder at night to provide hot water throughout the day, but when its gone it'll be a while before it gets hot again!

 

[doitmyself]

I am curious though, you must have a way to have hot water off the boiler; perhaps its gravity.

From the picture it looks as if it is a direct cylinder.

 

[TC.]

From the picture it looks as if it is a direct cylinder.

yup - the cylinder is directly heated by the immersion heaters!

 

[TC.]

i dont think from what i can see - the boiler has anything to do with HW supply. Im guessing that rather unusually the boiler is for the CH circuit only. Leaving the leccy immersion heaters to heat up the cylinder!

 

[ivrytwr3]

You're not the first to recommend this - ok, so looking at the set up i have, what would this cost and who would do it to link the hot water to the boiler?

 

[Billy Bob Bob]

you would need a different cylinder (indirect) a 3 port motorised valve,room stat,cyl stat but this would be a safer set up and cheaper to run

 

[TC.]

how old is ur boiler? and what make is it? me and boss ripped out a system like yours and fitted a combi boiler for 2k. was a giant system tho, and we were there for two days!

if you have the cash you would be better off investing in a combi boiler - the best on the market is a worcester bosch boiler! we have been getting them to 98.7% effecient!

though plumbstop are doing cheap boilers - glow worm i think, however these are B rated boilers and less efficient! stay away from Baxi!!

if you upgrade to combi - you HW pressure to the taps/bath will increase as it will be mains fed!

however if you really want to stay with your current set up - cant think why- other than cash issues, you would be better off going down to city plumbing, or screwfix, b&q and getting a replacement immersion heater, and paying a plumber to fit it, it should only take a hour max to fit and wire up. the options are entirely yours!

 

[TC.]

oh and just seen gasmans reply there is that option too!

 

[ivrytwr3]

anyone in Lincolnshire available - or any recommendations?!

 

[Rosebery]

Cylinder is already indirect by the looks of it.

 

[ivrytwr3]

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

[DLMURL="http://www.theelectricalcompany.co.uk/search.php?xSearch=bt7"]The Electrical Company > The Electrical Company > Electrical supplies[/DLMURL]

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?)

 

[GrahamM]

I would stop right there and get someone qualified to do the job.

 

[ivrytwr3]

lol, why? everyone is telling me how simple a job it is!

 

[TC.]

it may be a simple lookng job but if you screw it up you could end up causing alot of damage to either the building or a person through the spillage of scalding hot water.

you should get a plumber in to do this job.

 

[ivrytwr3]

too late now, i'm half way through the job!

I took the thermostats out to have a look at them, sizes any obvious damge, make sure i order the exact replacements etc. My question is, when i get the new ones, i am unsure as to which sides the 2 x wires (white and grey) go into. Is it like a 3 pin plug and they come with a wiring diagram?

Any help/pictures would be very much appreciated.

 

[GrahamM]

No one here should or would condone you messing about with electrical connections for which you have little knowledge of.
No one knows how this is wired up without looking at it and doing the relevant electrical checks to confirm it has been done correctly.
This is a bit more involved than sticking a plug on a toaster and has the potential to be more dangerous if done incorrectly.

I'll say it again, call a competent person to finish what you started.

 

[ivrytwr3]

Had an Eon engineer at my place today to change the meters over. I asked if if he did 'private work' and we spoke about changing the thermostats - he said if i could change a plug i could change the theromostat.

And on here and diy.com, people have advised it's a simple task.

My only concern now is, on the thermostats i have taken out, there are 2 x holes/screws for connecting them to the element/tank - and i have 2 x wires, one grey and one white, but there are no markings on the thermostat as to which wire goes where.

So my question is, does it matter which way it is wired, if it does, which goes where!?!

But thanks for the warnings.

 

[ivrytwr3]

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

 

[ecowarm]

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

Where in lincs are you?