Comination cylinder overflowing water from top

[tonydee1965]

Central Heating system problem....
Hi,
I believe I have a combination cylinder (fitted in my basement of our 3 storey home) as it has a top section with a lid and a float/ball valve there when i take the lid off).

Bascically, water is seeping over from the top.
I have checked the ball valve & it looks fine. I have taken it apart, cleaned the washer and replaced (adding a slight bend in the arm) to lower the water level but this has had no effect.

I have temporarily removed the cold water connection to this ball valve in this top header tank BUT water still fills up there somehow & seep out.

I belive water is feeding up from the pipe from the bottom section of the cylinder tank.
The unit is about 6 years old.
There are no tanks in the loft at all, only a small potterton bolier on the 1st floor.

Any suggestions ? tri valve ? Pressure to high ?

Thanks

 

[picasso]

It sounds like the coil has pinholed, I am guessing you have a thermal store so turn off the cold water feed to the whole cylinder and if the water stops rising its a new cylinder you need.

 

[Agile]

I agree that it sounds like a thermal store ( or sludgebucket as we call them! ).

A picture would confirm, but regardless, you are likely to be engaging a professional to do the replacement. They are not cheap either! I seem to remember about £800 when I priced a larger one a few years ago.

Generally, I would usually be advising a different system NOT using a heatstore.

Tony Glazier

 

[tonydee1965]

You'll have to educate me on the new terminology though ie 'coil pinholed' & 'Thermal Store'.
Could you be saying that water is pinholing out of the internal coil (Heating coil) into the main cylinder lower section and forcing its way out through the bottom 22mm pipe and back into the top header section (via the ball cock mechanism) ?

fyi:connections to the bottom section include:

the immersion heating element (for the electric side) should the Gas heating not work.
It also has the pipes leading to the Return Flow Valve/Pressure Reducing Valve etc.
Cant see a Cyclinder thermostat anywhere though.

In taking some of the water out from the top (using a small bucket), I did not that there were little bits floating about (e.g. little insulation bits - used for cavity insulation)). Notsure if this helps diagnose the prob.

 

[picasso]

any chance of posting a picture as were are doing a fair bit of guessing.

 

[tonydee1965]

I will get some photo's acros to you at around 6pm today (when I get back to the house).
Many thanks.

 

[gasservice85]

tony and picasso are correct if you turned off the cold main and the water still rises you definatly have a hole in the coil of your cylinder.

cheaper than this cylinder will be a small tank on the wall above and standard cylinder.

i would recomend getting a proffesional though

 

[tonydee1965]

......offending cylinder.
They are in the Album called : 'Water_Cylinder'.

Are there any other tests I should do before I replace the cylinder.
Also, I have a Potterton boler (small) firing up the heat for this and have been offered a larger Vallient from family (who have replaced for a new one). Is it worth replacing the boiler to this at the same time (to give a bit more heat/'power' perhaps).

Thanks
Tony

 

[picasso]

Your going to have to replace the cylinder,the domestic hot water coil has pinholed, your probably looking at around £1200 for the cylinder plus labour, I would look at an unvented cylinder as an alternative.

 

[gasservice85]

i would expect you would struggle to find a qualified engineer willing to fit a second hand boiler especially if it is non condensing.

also i would question why you would want to install a boiler that someone has replaced

for what reason?

 

[Agile]

If the new cylinder is correctly sized then the existing boiler will be totally adequate.

A boiler spends less than 10% of its time heating water. To slightly shorten the reheat time when its not relevant means it will be less efficient for 90% of its time!

Tony

 

[tonydee1965]

Many thanks for your prompt posts.

Just one further addition to my issue,

.....before I went to bed last night I reduced the pressure (on the 'Pressure Vessel' - ie the red fat round bulky item - as in the photo) down from about 1.5 Bar pressure to 0.5 Bar pressure) by turning the black knob at its top.
This morning, on inspection, the water did not fill up and overflow [in the upper section (header tank)] of this combn cylinder.

Could this be a temporary solution, or would I still need to replace the ehole cylinder ?

@Tony

 

[picasso]

on the picture there are 2 coils, the lower one is the heating coil which is connected directly to your boiler and the red expansion vessel which you have lowered the pressure on, if this coil was leaking you would be topping up the pressure constantly so this is not your problem,

the upper coil is under mains pressure, when it has a pinholed it fills the cylinder because the cylinder isint under any pressure, so the level rises and runs out of the overflow.

View media item 35843

 

[tonydee1965]

.. so just to clarify, the problem you suggest still lies with the Cylinder 'pinholing' and hence needs replacing ?

 

[tonydee1965]

.. also, why would lowering the pressure as I did last night (ie for the lower coil you mention) slow down & possibly stop the overflow above if the upper coil has still 'pinholed' as you say ?

Thanks