Woken by a near catastrophe

cormie

I woke up in the middle of the night to the hot water tank going bananas. Was boiling like made so I put the hot taps on and it spewed out, had to leave them on for a good few minutes. Sounded like it was seconds from blowing (can they actually blow if you leave them long enough?)

Anyway, it's puzzling, as the water is on a timer, and has been for the past age and this has never happened before. It's always the same amount of time it's on for and when I wake up to a hot tank and have a shower and finish with the cold tap (it's supposed to be good for you) it usually makes me scream with it being so cold, this morning I finished with the cold again, but there wasn't a sound out of me. It wasn't hot or anything, but it wasn't freezing.

So what could have happened that caused such an excessive heating and the cold water to be heated too?

Any feedback appreciated

DublinDilbert

cormie wrote: »

I woke up in the middle of the night to the hot water tank going bananas. Was boiling like made so I put the hot taps on and it spewed out, had to leave them on for a good few minutes. Sounded like it was seconds from blowing (can they actually blow if you leave them long enough?)

Anyway, it's puzzling, as the water is on a timer, and has been for the past age and this has never happened before. It's always the same amount of time it's on for and when I wake up to a hot tank and have a shower and finish with the cold tap (it's supposed to be good for you) it usually makes me scream with it being so cold, this morning I finished with the cold again, but there wasn't a sound out of me. It wasn't hot or anything, but it wasn't freezing.

So what could have happened that caused such an excessive heating and the cold water to be heated too?

Any feedback appreciated

Don't mean to be pedantic, but as such you don't have a hot water tank, i presume you have a copper cylinider..

Was the immersion timer on when this happened? ( i assume it was )...

It could be the thermostat is sticking closed on the immersion... You could try adjust it lower and see if that makes a difference....

It probably sounded a lot worse than it actually was, there is an expansion pipe from the top of the cylinder which will send the excess water to the attic. If you had of put on the cold tap in the bathroom you probably would of gotten luke warm water out of it.

Pete67

The hot water cylinder has boiled and this caused hot water and steam to be driven up the vent and into the cold water storage tank, heating it. The only way this can happen is if the thermostat in the immersion heater has failed in the 'on' position and does not switch off the electrical supply to the heating elements when the water temperature reached setpoint.

The thermostat is easy to replace if you have basic electrical skills, but DO NOT GO NEAR IT if you do not know what you are doing. Having got that warning out of the way, here is how do do it. Isolate the electrical supply to the immersion at the fuse board, and switch off at wall switch. Remove the round metal cover over the end of the immersion heaters. You will see a small thermostat with a dial which should be set to 60degrees. Note how it is connected (draw a sketch and label it with wire colours etc) Disconnect and remove it, and obtain a replacement from an electrical wholesalers. Connect it up making sure no stray copper conductors are sticking out. Tighten up the terminals well, a poor connection here will overheat and could start a fire. Set it to 60 degrees. Replace the cover, switch on and test.

Certain installations have two separate heating elements in the side of the cylinder, if this is the case either one could have a failed thermostat and you will have to check both. The more common dual element immersion heater is mounted on the top of the cylinder.

If you don't want to tackle the job yourself, any electrican will do it for you.

bugsntinas

we had that happen to us a few year ago in a rented house.the person they sent round said the thermostat was brocken.he said only run it a while at a time.bad idea as the water tank in the loft boiled away filling the roof space with steam and eventually brought the ceiling down.definately get the thermostat checked.

cormie

Jaysus. I'm in rented accom myself, don't have an attic in my place, I just have a cylinder in the hotpress. Actually had another near catastrophe last year when I woke to the smell of burning, followed the smell to the hotpress and it was the old timer that was smoking. Got an electrician in and he sorted it, put an e7 timer on it which is supposed to be really good. Turned the dial one day and then for ages, it would never switch off when it was supposed to by the timer, so I'd have to just use the boost function instead and leave it for 2 hours, then I got the dial working again and it turned itself off. So maybe last night it just stopped working properly again and it's the timer keeping it on?

The landlord covers this kind of thing anyway so whatever it takes, I wont be paying, just as long as it's done right

cormie

Oh, the water from the hot tap is now kinda browny. I'm guessing this is just from it boiling the crap at the bottom of the tank and it being mixed about? Should I just leave it running until it's clear?

Pete67

The brown water will run clear eventually when the sediment settles back to the bottom of the tank. A faulty switch/timer would not cause the problem you experienced, because even with the switch permanently 'on' the thermostat in the element(s) should shut them off when the water is hot enough.

cormie

Ah ok, so definitely a thermostat problem you reckon? Maybe it's been like that for ages, because the electrician said when he was installing the thingy that it'll save you money, because it will only heat it to a certain amount every night and then switch off. It seemed to always stay on for the same amount of time even if I didn't use much water that day and maybe last night it just got stuck on the timer, and because the temostat never worked, it just kept it boiling away while the timer was stuck!