F&E Tank Overflow query

[AshtonM00]

Hi there,

Just uploaded pics of both the CWST & header tank + associated pipework (not fantastic pics I know).

I also managed to put the camera over the F&E tank. I can see the water level is too high & mucky. I had my boiler replaced in January 2020 (conventional boiler replacing ancient back boiler) & a radiator power flush done at the same time.

Seems like more than 1 potential issue here then - no overflow, water level too high, mucky water...

I have the boiler service due early next year so will raise this. Bit concerned now!

Ash

 

[fixitflav]

At least you know now you have a float valve. Usually the pipe goes through the tank wall to the float valve, above water level. Maybe the pipe with the iso valve goes behind the back of the tank, then up, but can't tell from the pic.
I assume the other pipe is the open vent. The top of the inverted U should be minimum 450mm above the water level. It doesn't look like anywhere near that so surprised if you don't get pump-over. Perhaps you do, which might explain the crud.
You say the F/E tank is at high level, above the CWST, but AFAIK there's no reason it needs to be, is it possible to lower it? Then you could get the 450mm and things would be more accessible as well. And fit a dedicated overflow out to the eaves.

 

[fixitflav]

Another thought - what I said about 450mm and overpumping only applies if the system is piped the modern way, boiler - open vent - cold feed - pump. The older way was cold fill - boiler - open vent - pump. That avoids overpumping but gives other potential problems.

 

[denso13]

Seems like more than 1 potential issue here then - no overflow, water level too high, mucky water...

Yes, not a great cistern installation.

 

[AshtonM00]

Thanks for your input guys. Noted what you say about possibly lowering the height of the tank & then giving it a dedicated overflow. It looks like Fernox F1 has been introduced into it in the past & I did read somewhere on these forums that lots of people experience the appearance of muck after introducing it so could that be partly responsible? This would have been introduced into the system prior to us moving in but the boiler being replaced was less than a year after us moving in so presumably the system would have been drained when that took place (I know the rad's were flushed).

Ash

 

[Harry Bloomfield]

My tank with F1 was clean/clear, so I would suggest the flush was maybe not as thorough as you suggest - it needs to be done again and properly.

I would begin by isolating the CW supply to that tank and syphoning as much of that out as you can then a drain down, flush, drain, flush until it runs out completely clear. Add the missing overflow pipe and bend that valve arm down so it shuts off well before the overflow level.

 

[AshtonM00]

Thanks Harry,

I'll find a decent plumber/heating engineer to carry out the works.

Ash

 

[Harry Bloomfield]

Thanks Harry,

I'll find a decent plumber/heating engineer to carry out the works.

Ash

Make sure F1 is added at the end of the process.

 

[fixitflav]

Thanks for your input guys. Noted what you say about possibly lowering the height of the tank & then giving it a dedicated overflow. It looks like Fernox F1 has been introduced into it in the past & I did read somewhere on these forums that lots of people experience the appearance of muck after introducing it so could that be partly responsible? This would have been introduced into the system prior to us moving in but the boiler being replaced was less than a year after us moving in so presumably the system would have been drained when that took place (I know the rad's were flushed).

Ash

Looking again at the pics, you clearly haven't got the 450mm, or any way of raising the open vent to provide it. Have you checked how the system is plumbed? If it's the modern way you're almost certain have pump-over, and associated problems.
The earlier method doesn't give pump-over, but each time the pump starts the water level in the vent pipe falls (and the tank level rises slightly) an effect known as seesawing, which brings aerated water in, adding to corrosion risk.
As far as we can see from the pics, it doesn't look like lowering the tank would be a problem.

 

[AshtonM00]

Hi all,

I've now had an overflow fitted to the F&E tank & it Tee's into the CWST overflow. The tank was also emptied & cleaned out & inhibitor added. The heating engineer/plumber said the state of the water in it wasn't too awful, it was just murky but nothing worrying in it. Thanks for all your help & advice. Great forum.

Ash