Bleeding rads and header tank

[Deleted2797112]

Hi,
I have a back boiler, hot water tank on first floor and cold water and header tanks in the loft. The first floor rads need bleeding every week or so, ground floor are fine.

Been working my way round the loft doing insulation and laying boards and just reached the corner where the tanks are. The water level in the header tank is very low. The ballcock arm has at some point been tied up to something but the tapes are no longer attached to whatever it was tied to.

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If I press the ballcock arm down, it lets water in through the inlet pipe so that seems to be working. Is the low water level the reason I'm getting air in the rads constantly. I read back some old posts on the forum about bleeding the rads and topping up the tank over again until all the air is gone. is this what I need to do? If so, what is the normal water level so that it doesn't happen again?

Very grateful for any help!

PS should the tank have a lid?

 

[Armo74]

Looking at the water in the tank it looks very sludgy, i would suggest that your cold feed is probably blocked where it tee's into your flow pipe from your boiler. That will be the reason for the constant bleeding. You need to locate the cold feed and run a magnet up it that will indicate where the blockage is,cut the blockage out and re-pipe.

then drain some water out ,clean your tank out and add some sentinal x400 and run your system for a fortnight then drain and re-fill adding sentinal x100.

The tank should have a lid and be insulated to.

The water level should only be about 4 inches deep.

 

[Onetap]

PS should the tank have a lid?

There should be a lid, to stop dirt getting in and reduce the amount of water vapour getting out and condensing in your loft.

Back boiler; gas or solid fuel?

The water level should be a couple of inches above the cold feed outlet when the system is COLD. The empty space above the water is to accomodate the expansion of the water in the system when it is hot.

 

[Deleted2797112]

Hi, thanks for the replies!

I'll have a closer look at the water in the tank - it didn't look particularly sludgy - it's possibly the picture as I had to hold an inspection lamp over it as it's in a very dark corner. If it's a blockage as you suggest, that's going to be a bit beyond me to do. I wss hoping there were a few simple checks/fixes I could try myself first. This is probably a completely stupid question but I'll ask anyway as I want to understand how the system works - if it was a blockage as you suggest, would that not stop all the rads warming up? My downstairs rads are fine, it's just the upstairs ones that get cold again about a week after bleeding them.

The boiler is a gas one.

The water level should be a couple of inches above the cold feed outlet when the system is COLD

Can I just double-check my understanding please - this the outlet low down on the tank on the opposite side to the ballcock inlet that takes the water down to the boiler? I'll let the system get competely cold and have a look at where the water level is then top up to the level you suggest if necessary and try bleeding again.

I'll sort out a lid thanks! The tank has a very thin insulation jacket on it. I've got more of the black plastic covered insulation panels so I'll put them round the tank. I've also cleared away the insulation underneath this tank and the big cold water tank too.

Thank you!

 

[joe-90]

Those tapes would be tied to a bit of timber laid across the tank to keep the ball valve closed while they did some work without it filling up.

 

[Deleted2797112]

Thank you - I did wonder!

 

[Deleted2797112]

I've let the system go cold and checked the level in the F&E tank and it's at the level suggested, just a couple of inches above the feed to the boiler. The water isn't sludgy at all - I can see the tank bottom clearly and the outlet valve and when I bleed the rads, it's not dirty.

So I've bled the rads, got a lot of air out of two of them. By the time I got back into the loft, the ballcock valve was running re-filling the tank and it stopped filling when it got back to the same level as before. So that seems to be working OK.

I know there's a small leak at the on/off valve of the bathroom ladder radiator but I've kept that turned fully off until I can get round to dealing with it. Can it be letting air into the system even though it's been permanently off? There are no other leaks that I can find.