header (f&e) tank overflow pipe drip

Hi, after some confirmation please after reading up here an other forums.

Have conventional boiler, hot water tank, cold water tank & small header tank.
Overflow pipe from header (f&e) tank has constant drip.
Ballcock not leaking and works as it should - level of water goes over max. should be.
There is (what I assume is) an overflow pipe from the hot water tank that feeds into the bottom of this small tank.
When hot water or heating pump is on I think I can feel the water coming in this bottom pipe - and feel vibration.
Have tried turning boiler temp down - no difference. Now trying turning pump down from 2 to 1 as read that may help short-term (not a permanent fix I know)
Also water in header tank is quite scummy, with deposits at the bottom.

Sounds like it could be pump/valve issue, or leak from cylinder.
Either way looking at service call right ?

Thanks in advance for confirmation. John

edit: sry should have added I have a care agreement thing, just wondered if a quick fix & check my diagnosis.

Confirmed, a Plumber is required

UPDATE:
homecare visit for f&e tank overflow drip 23/08.
First off said I needed Powerflush @ £850.
Then changed pump when he saw the hot water coming back into the f&e feed. Showed me pump after and all furred up. Said this will be OK short term but need powerflush once heating is on & won't change pump again for free.
No more f&e overflow drips.

Advised cold water tank ballcock leaking. 28/08 changed all OK.

29/08 - f&e overflow drip returned - checked and water level is over ball valve (ie. over half way up the ball itself but ballcock valve appears to be working) - removed approx 4ltrs of water to get back to normal level

Any ideas before I call them back again ? Thanks

This is normally a cylinder leaking into the heating coil.

Of course a Homeserve nupty will not recognise that on the first visit.

But just keep calling them.

Start an argument if you like and at the end say you are going to call an independent expert to diagnose the fault and will charge their cost to them!

That threat MIGHT get them moving!

Thanks - will call them again.
Has been fine for a few days, but now seems worse. Emptied approx. 6ltrs from h&e tank this morning @ 8am - 2pm have noticed dripping again and emptied same. This with no heating or hot water on.
Previously dripping was only from overnight - during day was fine if I emptied some.

New cylinder needed.

Andy

UPDATE & resolution.
took 2 x visits & had to wait 2 weeks between but agreed diagnosis of new HW tank with BG.
They insisted system left off overnight to prove not system blockage. Did this (fortunately not cold yet) and still overflowing.
New HW tank & immersion & switch & associated plumbing to fit scheduled for next week. And we've had new pump fitted also during diagnosis which is massively quieter than old one.
Still saying should have powerflush, but not essential yet. At £800-ish they have that right - any idea how much this would normally be ?
Thanks for input. Jon

the system may well be dirty. Powerflushes are a great moneymaker, and people who provide boiler maintenance services often push them.

If you can do basic plumbing, you can do a chemical clean yourself which will get quite a lot of dirt out, and will often be enough (provided you have not actually got a blockage yet) and save you hundreds of pounds. If you are having a new cylinder fitted next week I would be strongly tempted to rush out and buy a litre of Sentinel X400 or X800 today. You need to know where the drain cock is, and where the feed and expansion tank is.

If you can fit a system filter, or get a plumber to do it, on the return pipe to the boiler, it will do a great deal of good, combined with the chemicals. You might spend £35 on chemicals and £100 on a filter, plus the time to fit it, and will learn to drain and refill your system, which is not actually difficult but takes time, so is expensive if you pay someone.

JohnD - will look into that - thanks. No chance to do before service visit unfortunately.

UPDATE: Tank replaced (1st didn't fit, second did but took most of day in all) & all seems well. Had new HW isolation tap fitted at same time.