water in the terminal of immersion heater

[Caren Mccabe]

hi does anyone know possible cause of water in the terminal of immersion heater? electrician said he never saw this problem before and suggests a heating/plumbing expert but has disabled it till plumber is able to call......no hot water and this has only happened since wood burning central heating stove installed in march....terrible overflow prob from loft....is it related? Thanks for any help or info

 

[ruston]

More than likely if the tank is under the leak. Your overflow is probably because the expansion tank can not cope with the output of the wood burning stove and is causing it to fill and either flow out the overflow pipe or come over the top of the tank. Your electrician is right to advise you to get a heating engineer as this could be a potential scalding problem if this is what is happening.

 

[Caren Mccabe]

thanks for now.....plumber due Thursday and electrician Friday so wanted some knowledge before discussing plans for repairs etc! will try to get my head around this before they blind me with science!

 

[ruston]

Well if it is a gravity system there will be a cold fill water tank in the loft to replace the hot water you draw off. Wood burning stoves produce a tremendous amount of heat and can overheat the water in your cylinder which in turn transmits the heat to the header tank , which then expands and flows out of the overflow. In extreme circumstances the water can become as hot as the water in the tank and if the header tank is plastic this can collapse and flood your house, or even worse scald someone underneath it. Safety measures should have been put in place to prevent this happening, but as you are having overflow problems it dose'nt look like it.

 

[MarkieSparkie]

Heed the sound safety advice above and please don't use the wood burning stove or immersion heater until such time as plumber and electrician indicate it's safe to do so.
I have experienced this type of fault on a simple immersion heater system, it was caused by a pin hole in the end of the thermostat pocket, which only weeped when the tank was hot causing condensation/moisture to form on electrical contacts and cap of the immersion heater. This is probably not the most likely cause in your case considering the overflow problem you also experiencing, but it does illustrate that other unrelated causes are possible.

 

[snowhead]

The only cause of water in the terminal section of the immersion heater is is as above, pinhole or other leak thro' the element.

The heater needs replacing.
Heaters fail this way thro age, it's not uncommon.
It may have been worsened by the overheating.

The overflowing and overheating is probably faulty design of the system with the wood burner or it may just need the float valve adjusting.

Who designed and installed the woodburner, they need to come back and sort it out?

Does the hot water from the tap get very hot and steam??

If above is yes the system is in a potentially dangerous state.

The header tank that's overflowing should be a galvanised tank not a plastic tank.

 

[oldtimer]

Can I ask if it is a standard UK immersion or is it a non standard european I think Mega Flow system ? because I have had this with a couple of non standard units. Will try and dig up the info.

As above it called an Atlantic mega flow where the water leaks out off the element casing but it is actually the tube that is at fault ie the element is down to earth and the tube looks like it is sweating inside. By the way Atlantic UK are bust but I have the contact details of the agent also a lot of these were speced for a lot of Barret flats/houses

 

[oldtimer]

Any reply to this ?

 

[ruston]

Any reply to this ?

She might get back after the plumber and spark have been, Thursday and Friday respectively.

 

[rsp84]

Havent any experiance in wood stoves really, but if theres a header tank, (not the cold feed to the cylinder) then the overflow (which pokes out of loft to outside) would suggest a fault with the ball valve float sticking open.
If its the vent pipe of the cylinder into the cold feed tank then there maybe an overheating of the water or a possible blockage in the system and its pumping over rather than cycling the heat round(even possible that the height of the vent pipe was never calculated accuratly and is inadequate for the wood stove)

 

[oldtimer]

Caren it could be the wood burning stove is boiling the water in the immersion I take it there is some sort of heat exchange in the woodburner that uses a gravity feed if this is the case then I take it the bubbling out of the vent pipe is when the wood burner has been on for 2-3 hours so in a sense you have a big kettle on your hands because you have no temperature control.

So when you run the hot tap during the bubbling does it come out scalding hot ? If so you need some sort of heating control if you go back a few years like me the coal fire used to do the same job but only if you redirected the heat going up the chimney to a heat exchanger behind the fire when or if the immersion got up to heat you redirected the heat back up the chimney so it could be that your wood burner does not have this facility although this could be handy in the winter if you redirected this to the CH system.

Just to add you could be getting a leak if you are bubbling as you put it the immersion tank that is meant to control at 60-65oC instead of 100oC (boiling point) and at that temperature things can expand to develope a leak

 

[rsp84]

Hopefully there will be a high limit stat, stops the water boiling (eps dangerous if the feed tank is made of plastic as there been cases of it melting and taking ceilings down).

 

[oldtimer]

Havent any experiance in wood stoves really, but if theres a header tank, (not the cold feed to the cylinder) then the overflow (which pokes out of loft to outside) would suggest a fault with the ball valve float sticking open.
If its the vent pipe of the cylinder into the cold feed tank then there maybe an overheating of the water or a possible blockage in the system and its pumping over rather than cycling the heat round(even possible that the height of the vent pipe was never calculated accuratly and is inadequate for the wood stove)

In Scotland the vent or the expansion pipe is vented out on to the roof ie the pipe is shaped like a swan neck but my understanding that in England some of these pipes vent into the cold water tank not a problem if immersion is ok but when the stat fail it can boil and worse still if the cold water tank is plastic this to can boil then split.

Be aware an infant died a few years ago due to this and i am not sdure but I think that was the reason for fitting a high limit cut out switch on the control stat

 

[rsp84]

+1 old timer, and sorry didnt realise there maybe different installs in scotland. I guess down here we like recyling the venting water :laugh:

 

[ruston]

Hopefully there will be a high limit stat, stops the water boiling (eps dangerous if the feed tank is made of plastic as there been cases of it melting and taking ceilings down).

Simply put if it is a gravity fed system there will be two header tanks , both will overflow externally, however both have expansion pipes fed into the respective header tanks . If the water to either the domestic or heating water is allowed to run unregulated the hot water will expand into one or both of the tanks and can easily expand to the top of the tank reaching boiler temperature.I have seen the external overflow not be able to cope and hot water erupt over the top of the tank and come down through the ceiling. As Old timer has said the old style back boilers had no regulators other than a damper and it was common to boil the hot water in the cylinder, the remedy in those days was to run the hot water off. Hope this helps a bit.