Sometimes water dripping from expansion overflow and sometimes sudden water discharge

[samsg30]

Hi,

I have: -
- an open vented central heating system with F&E tank in the loft.
- Sealed cylinder hot water (megaflow). Guess it won't matter with the issue explained below
- Boiler is flexicom hx30 heat only.

Most often (but not absolutely everytime), water drips from the expansion tank overflow even when only water in megaflow sealed cylinder is heating up and no central heating is running. Sometimes a sudden burst of water comes out as well. *** I can also see some sort of blackish sludge type hanging out of expansion overflow pipe exit on the outside wall ***

Though everything with hot cylinder seems working ok, I recenlty noticed that radiators on the ground floor (in 3 storey house) are not warming up enough. Infact when radiators on top two floors are very hot to touch, ground floor radiators are only slightly hot and I can feel the temperature difference between top and bottom of the same radiator on ground floor.
Last month, one of the ground floor radiator was replaced with new and another radiator was emptied completey for changing lock sheild valve. Whilst partially draining the system for doing above job, just slightly dirty water came out.. light brown in colour.

Also whilst working of partial draining the system, I noticed sludge in F&E tank in loft when I put my hand in the water. I don't know if it is black or brown sludge but guess it makes a huge difference so I am going to check tomorrow.

Please can anyone suggest if dripping water from Expansion overflow (without demand for central heating and only demand for hot water) is related to raidators on ground floor not heating up (may be due to sludge came down to lowest radiators very soon) ? And what actions could I take to identify actual cause and remediate it.

Thanks.

 

[Simon F]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

if the f+e tank is overflowing repeatedly then the water is coming from somewhere.
possibilities -

water level to high ( float issue ) overflows on heating and replenishes when cooled
split cylinder coil
dripping fill valve
blockage causing pumping over etc

get into the loft and observe what is happening

radiators not heating -

pump, blockage, balancing

 

[Pro Action]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

Are the cold feed and vent on the flow pipe before the pump? If not it could be pumping over.
Flush and protect system, pump may need replacing if it's worn. If there isn't one already fit a magnetic filter on the return by the boiler, before the flush.

Turn off the radiators on the upper floors and put the heating on.
If the rads on the ground floor then heat up enough, that would indicate that the system needs balancing.

 

[samsg30]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

I went into loft and had a good look inside F&E tank. It is full of black dirty water and I can see quite a bit white jelly type thing floating in it.
Also water level is right at the edge where overflow pipe starts. For testing purpose, I pushed the ball valve down a bit to let some more water flow in and they went straight out from overflow pipe. I put hand in that disgusting water and can feel bottom of the tank has got good layer of sludge.

So if we look at water dripping issue, it raises two questions: -
1) Should water level be right at the edge of overflow pipe or few inches below it to allow water expansion when water in the return/flow pipe heat up.

2) Is that white jelly in water and absolute dirty water with sludge at bottom of F&E tank normal? or should I be looking to clean it and fill with fresh water. I did put 2 liters of Fernox F1 inhibitor a month back when system was drained to fit new radiators.

Attaching picture of F&E tank from inside and outside

 

[tamz]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

Who cares what it looks like. Its a bacteria breeding ground.
Bend the ballcock down and go get a tetanus shot.

 

[samsg30]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

Is there any point in cleaning that tank by taking the water out from F&E tank via hose? This will take existing bacteria and sludge out. I'll bend the ballcock down to avoid overfilling. Not sure how quick it builds up and if it is of any concern? Like you said who cares.. so it is good to assume there's nothing to worry about with dark murky water and white jelly.

I can smell chemical when I opened the lid and some other posts on google suggests inhibitor have a tendency to come back in F&E tank via expansion and look like jelly. Atleast it is not brown sludge on top which would be of more concern.

 

[tamz]

Re: Sometimes water dripping from expansion overflow and sometimes sudden water disch

Personally, unless i was scratching my rse for work i wouldn't bother but its up to you.
Easy sell if you have the time.