Boiler Banging and Extremely Hot Water

[Innocent1]

Hi,

I am novice girly here, just looking for advice!!! For a couple of months my water has occassionally been boiling hot, even if I am sure I had not had the boiler on. Now I have returned from holiday and put the heating on and the boiler is making a strange banging noise (it sounded like a locomotive so it was quite rythmic!). I switched it off and the banging stopped only when I ran the bath and the water was scalding hot. What could be the problem? I have boiler that says (Wickes 3kv 240v Type pc 27) on the top on a silver thing, and my heating is from a oil storage tank in the garden. I moved into the house 6 months ago so not sure how old any of this stuff is. Oh and I can't check the oil in the garden tank as there's no gauge like I thought there might be??? Please advise ASAP before I start calling god knows who and paying out!!!!

Sam

 

[Hugh Jaleak]

Firstly, for your own safety, please switch off the boiler and make sure the immersion in the hot water tank is also switched off. Then, run off a quantity of hot water to reduce the temperatures in the water tanks.

Banging is usually a sign of overheating, but I am confused as to why the banging has occurred even with the boiler off. Has the immersion been switched on when the banging has occurred?

 

[Innocent1]

Yes the immersion has been on when the banging has occured. I also ran the water into the bath this morning as you suggested. I think I may have got some of my words muddled this morning too! I think its either the water tank (in the loft) or the hot water tank in the airing cupboard that is banging (not a boiler). I presume my oil tank in the garden heats the water, as I know it does the radiator's. I do have a small boiler in the kitchen, but that isn't making any noise, and I think only boil's water for a downstairs shower. Could it be a problem with a pump or the Honeywell timing device (this seemed to ignore any settings I had on it)? Also I had a leak in the loft and a plumber fitted a new ball valve in the cold water tank, but I don't think this is related as the water was over heating long before this (but the banging wasn't occuring then).

 

[Hugh Jaleak]

I did think looking back over your first post that you may have the terminology a little mixed up, not to worry.

It'll be the hot water cylinder doing most of the banging, i'll lay money on the immersion heater thermostat has failed, basically the immersion is boiling the contents of the cylinder. It is vital the immersion is turned off and left off until the problem can be rectified. Also, please run off some hot water to reduce the temperatures. When this situation occurs not only will the cylinder boil, but it can also cause the cold water storage tank in the loft that feeds the cylinder to boil too. If this tank is made of plastic they can begin to deform through the heat, and there have been instances where the plastic tanks have collapsed, pouring boiling water through the ceiling. (In one case a baby was sleeping below, the result was sadly, fatal.)

The oil boiler may well heat the cylinder as well as the radiators, with the immersion switched off, see if you still get hot water. If you dont there is likely to be an unrelated problem elsewhere.

 

[Innocent1]

Sorry for my bad use of the terminology! Yes the cold water also went hot too once. And I think the cold water tank in the loft is plastic. So, if the immersion heater thermostat has failed I need a plumber rather than a heating engineer? How much is that likely to cost to replace? I know you can only give ball park figures! And a final question, I ran the hot water out after turning off the immersion. Now I have done this, do I need to keep doing it if the immersion stays off? I'm presuming not, but just checking!!!

 

[Hugh Jaleak]

Immersion should be about £25-30, plus fitting, depends how easily the old one comes out! The oil boiler should be able to heat the hot water tank as well as doing the rads, be an unusual setup if it doesnt.
I'd be very wary of using the immersion until it has been checked, though if the boiler wont heat the hot water for whatever reason, then the immersion could be used in short bursts, but dont forget to switch it off again before it boils the water though!

Run enough hot water off to lower the temperature in the cylinder and thus the cold storage tank in the roof. It's the temperature of the water in the plastic cold storage tank that gives cause for concern, too hot and there is a risk of it deforming and/or collapsing. If the immersion is left off then the water wont overheat, the boiler will only heat it to a certain temperature before the boiler will switch off. (Unless that is banging too!)

 

[Hugh Jaleak]

Duplicate post.