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Trying to help a neighbour (as plumbers are seemingly impossible to get!) ...
A regular and persistent air lock preventing water supply to the bathroom. Can be cleared by running a hose from downstairs to the bathroom mixer tap, opening it on cold and forcing water back to the water tank ... you hear a bubble burst and then all is well for about a week. But it's happening every couple of weeks and much as I can pop around, not really ideal!
It's terraced 1900s 2 bed house; GCH and an older Potterton gas boiler in the kitchen; water tank in the loft with a header tank; electric shower with newish water pump; bath.
I looked in the loft and the pipe from the cold water has a very shallow drop and runs for 10ft before descending to the bathroom.
She's tried to get a plumber but a couple said they weren't interested and a couple aren't responding. I'd happily try to resolve if it's not too complicated ... but not sure what I'm looking for! Any clues?
Am I interpreting this correctly, is that the cold supply?
Why does the system run the cold from a tank? Usually that's for a high multi-storey house or low pressure/volume. Ask the water board to test that.
Are you sure that it doesn't run the cold to the taps, with a supply to the tanks? When it's working, put your thumb over the tap; if you can stop the water then it's tank fed
Conventional boiler or combi? Guessing conventional
Does the hot stop as well? If so I'd imagine that the hot water cylinder is getting emptied and air-locking. Doesn't necessarily explain the lack of cold though
IANAP but we need more detail: does it air lock when running the shower or the bath?
Shower will only be fed by cold and I don't see why that's running short of water unless there's a flow issue.
(See how long it takes to fill a big pan or something with cold water from a downstairs tap and work out the litres/min. Then do the same upstairs and see if there's an issue)
Sounds like it's the hot water air locking and the only reason I can think is that the HW tank is being emptied by the [newish] pump if it's on the HW in the bathroom as it's drawing more than the [cold] supply to the tank can refill.
One solution would be to fit a pressurised HW tank and get rid of the pump.
Sounds like it's the hot water air locking and the only reason I can think is that the HW tank is being emptied by the [newish] pump if it's on the HW in the bathroom as it's drawing more than the [cold] supply to the tank can refill.
Sounds plausible to me. I couldn't think how air was getting into the system
If that is the description they have given to potential Plumbers, I’m not surprised no one is interested.
So the cold water isnt flowing into the bath tap? Is the cold water feed direct from the header tank above the copper cylinder - is that what you mean by the ‘water tank' then? Is it just the cold water slowing down? Or does is affect hot too?
What is the electric shower pump? Is that just a fancy little mixer with a pump in it, rather than an electric shower?
If its just the cold, and that is fed from the hot water header tank, then I wouldnt even bother investigating it, I’d cap off the old cold supply, and fit a new mains fed supply to bathroom cold water. It could be as little as a hours work to tap into the feed to the header tank, and connect that to the cold outlet. You’d then have fresher water and a higher pressure going into the bathroom taps. Depending on what the shower is, that may need balancing, which is an easy job too, but may not need doing anyway.
Thanks all and sorry I've not got full details.
I haven't been able to find the mains stopcock in the house and I think, to turn off the water supply, you do this in the loft from the stopcock by the plastic tank (I think).
The airlock has been happening frequently pre the new shower and pump.
I think the airlock stops cold water as the toilet flushing is her major concern.
It's a conventional boiler.
I'll try and pop around to see how quickly the tank drains when running the shower, and also if I can stop the water flow by thumb over the tap
Thanks again
I haven't been able to find the mains stopcock in the house and I think, to turn off the water supply, you do this in the loft from the stopcock by the plastic tank (I think).
Be careful with random gate valves (sometimes have a red wheel on top). These can do anything from isolating the boiler to balancing the CH and HW.
Gate valves (as opposed to stop valves) aren't watertight
Hi, so a little more information.
I can easily put my thumb over the bathroom tap to stop the water flow.
I ran the bath and watched the stopcock / tank fill ....it was filling less quickly than the bath was draining it.
Have you tried measuring the flow both upstairs and down yet?
There may be an issue with the pipework going from the rising main up to the tank.... or even in the pipework before the house.
[when we moved in the flow was pretty crap - turned out the old galvanised pipe that ran 100m from the road to the house was 90% clogged up with corrosion. I had it all replaced and fitted a pressurised cylinder to get rid of the stupid tank in the roofspace - all good 23 years later.]
Is the shower pump supply using a suitable flange? It should be an Essex flange or similar (Google it they look quite distinctive). If not this can draw air into the system.
Well I managed to get a plumber in and he's confident it's the float on the tank. He's replaced it and filling much quicker now, so fingers crossed.
Thanks for the help
Haha.... never thought of the float valve!
Glad it seems to be sorted.
I'm pretty sure it's a feature of older system boilers. The cold water tank in the loft provides water for the hot water cylinder by gravity feed, and to ensure hot and cold water pressures are the same it'll supply all the cold taps as well. Or rather all but one: there'll be a single cold tap fed directly from the mains, this is likely the kitchen one that you use to clear the air lock.
First thing to check is turn on a bathroom cold tap then go up in the loft to see how quickly the tank refills - maybe the ballcock is knackered, or the ball valve upstream of the ballcock, and the tank is emptying quicker than it can fill.
Being an attic tank it could just be full of manky biofilm, dead birds, etc. and occasionally you pull a bit of scum, a dead bird's beak, whatever into the cold supply line and it needs a blast from the mains to free it up again?
The best solution would be changing to an unvented heating cylinder and mains cold to all taps, but that's not going to be cheap.
Second best, and probably the one I'd recommend if it's just you doing a good deed for your neighbour, would be to cap off the tank outlet the to cold taps while ensuring the supply to the hot water cylinder is still operational - it may be two separate outlets or it may be a single outlet that tees off to hot water cylinder/taps - then putting a tee into the mains supply to the tank and connecting all the cold taps to this instead, where you just cut and capped at the cold tank outlet. You'd need some pipe cutters, a few compression fittings, a couple of pipe spanners/adjustables and a bit of copper pipe to do this. Probably half an hour's work max if you think it through first and make sure you're using the right size fittings. Note: if you were to be cutting into any thicker pipe it might be 22mm but more likely 3/4" given how old the system sounds. The compression fittings you get these days will have 22mm olives in them, these won't seal properly on 3/4" pipe and I'd recommend getting some 3/4" olives if that's the case.
The downside of this fix is the hot/cold water pressures will no longer be balanced, and any mixer taps will not behave the same as they used to.
⬆️ Or you could save all that typing and just replace the float valve. 😁
Well, she had a full bath last night and no airlock so early days but hoping the new float valve will sort her!
Happy neighbour 👍