Balls, no water!

[-Z-]

Basically was showering the little 'un last night when both hot and cold water ran dry.

Poked around in the loft and found the cold water tank empty. Thought I'd try the simple things first and tried the stopcock for the tank. Lo and behold the tank started filling again (I think the stopcock was just open and the recent cold caused the pipe to contract slightly, just enough to shut off the flow).

Hot water was back to normal this morning, cold was weak but thought would normalise soon.

Wife just called to say water has gone again Is this going to be down to airlocks in the pipes maybe? How would this be sorted? Any other ideas and solutions appreciated!

[Ferg]

Yes, it sounds like an airlock.
You *could* try pushing mains water from a hose up the offending tap to puish air into the roof tank, but it's awkward.
Alternatively get up in the roof and look at how the pipe runs and you may well be able to see where it's 'locking. There's probably a horizontal out or the tank which then elbows down through the ceiling. Check the horizontal is rising towards the tank connector ant try to manipulate it a little (temporarily) so that you can encourage the air to run out into the tank. You'll hear it bubbling out of the tank connector.

[Deva Link]

-Z- said:

Basically was showering the little 'un last night when both hot and cold water ran dry.

Poked around in the loft and found the cold water tank empty. Thought I'd try the simple things first and tried the stopcock for the tank. Lo and behold the tank started filling again (I think the stopcock was just open and the recent cold caused the pipe to contract slightly, just enough to shut off the flow).

Hot water was back to normal this morning, cold was weak but thought would normalise soon.

Have you got cold water working in the kitchen?

Cold water normally is straight off the incoming main (no tanks involved). In some area the upstairs cold water comes from a tank in the loft.

If that's not filling then perhaps the stop cock either at the tank or elsewhere back towards the road isn't open enough. Maybe the mains presure has been reduced for some reason - are neighbours also affected?

[-Z-]

Thanks for the advice gents.

In reply yes downstairs cold water in the kitchen is perfect.

Everywhere else cold is only a trickle and hot water lasts a minute at good pressure then goes so I think it points to an airlock effecting both systems?

My feeble plumbing brain has told me to run the cold water tank dry then let it refill with the taps open in the hope that this may mobilize an airlock instead of trapping it?

Tried juggling the horizontal pipes but no dice

[Ferg]

You might clear it if you put a cork in the tank connector after emptying the tank, then wait 'til it's full THEN pull the cork out.

[Deva Link]

-Z- said:

hot water lasts a minute at good pressure then goes

That's a bit odd. A minute at good pressure is a fair bit of water. Is the tank refilling OK? Should be filling from the mains pretty well as fast as the hot water is being used.

[-Z-]

Deva Link said:

-Z- said:

hot water lasts a minute at good pressure then goes

That's a bit odd. A minute at good pressure is a fair bit of water. Is the tank refilling OK? Should be filling from the mains pretty well as fast as the hot water is being used.

A minute was an optimistic guess, just timed it at 45 secs

I've now managed to fix the cold water so the airlock has gone from that, but the hot water problem remains. I'd guess the airlock means the hot water tank is filling really slowly, hence why it's better the longer I leave it.

I've tried covering the outlet that goes from cold tank--->Hot water tank with my hand, I can only feel a very slight draw whereas if I do the same for the outlet that goes to the cold water taps you can def feel very strong suction. A bit puzzled how to cure the hot water tank since it's an isolated system?

Think I'm gonna admit defeat and call a plumber tomorrow! Anyone have any recommendations in the Chigwell/North East London area?

[Dogwatch]

Normally any air in the HW system should be vented off by the pipe which on older systems finishes in a shepherd's crook over the cold water tank. (I think that arrrangement has now been stopped but there are still a lot about).

[Deva Link]

-Z- said:

I'd guess the airlock means the hot water tank is filling really slowly, hence why it's better the longer I leave it.

The hot water cylinder doesn't empty and fill - it should stay full. When you open a hot tap, hot water is pushed out of the top of the cylinder by the cold water pressure into the bottom of the cylinder.



Once hot water if flowing then as long as the tank in the loft is refilling it should continue to run.

I can't see it causing the problem you describe, but is there a stop cock where the cold water goes into the base of the cylinder?

ETA: Could this be a problem with scaling somewhere? Don't get it in my area!

Or maybe some gunge from the bottom of the cold water tank got into the system when it first ran dry? Bit odd really - if you ignore the boiler and rads in the picture you'll see it couldn't be much simpler.

Edited by Deva Link on Wednesday 4th November 21:11

[MrV]

-Z- said:

Deva Link said:

-Z- said:

hot water lasts a minute at good pressure then goes

That's a bit odd. A minute at good pressure is a fair bit of water. Is the tank refilling OK? Should be filling from the mains pretty well as fast as the hot water is being used.

I've tried covering the outlet that goes from cold tank--->Hot water tank with my hand, I can only feel a very slight draw whereas if I do the same for the outlet that goes to the cold water taps you can def feel very strong suction. A bit puzzled how to cure the hot water tank since it's an isolated system?

Your not feeling much of a draw as the hot tank is not emptying to need refilling

Have you a mixer tap on either the bath or bathroom sink ?you may get lucky by first opening the hot tap till it stops running then holding you hand over the tap outlet, turn on the cold so cold water is forced up the hot pipe,hold it like this for 30 to 45 secs then remove your hand ,it might pull the hot through.

[-Z-]

I really am hard of thinking when it comes to plumbing, that diagram made my eyes go blurry

I understand how it works now, but the odd problem still remains

Warm water flows for about 45secs to a minute, then gradually dies down to nothing, cold water storage tank is full, house is only 7 years old too.

Cold water tank looks pretty clean inside. Oh and MrV, I'd already tried your suggestion inspired by the earlier post about hooking the garden hose to the tap, still no dice.

I guess the strongest candidate is gunk getting sucked up, regardless of how clean the tank looks now as before the tank ran dry everything was fine.

[Deva Link]

Baffling. With the house only being 7yrs old, there isn't some kind of hot water temperature limiting valve is there?

Also, once the hot water stops, how long does it take to recover?

[-Z-]

Deva Link said:

Baffling. With the house only being 7yrs old, there isn't some kind of hot water temperature limiting valve is there?

Also, once the hot water stops, how long does it take to recover?

Well the cycle is:

Turn on tap- get 10 seconds of good pressure hot water then 20 seconds of gassy spitting/spurting hot water then a reducing trickle.

Turn off tap for about a minute

Turn back on - same as above.

If I leave it longer like 30 mins I get probably and extra 20 secs of good pressure hot water.

Not sure about a valve, but on the boliler I moved the slider controlling hot water to 'Off' about 4 hours ago so shouldn't really be over heating I would've thought.

Edited by -Z- on Wednesday 4th November 23:44

[Engineer1]

We have a similar problem here but the cause is obvious, when we put the new kitchen in we (the MRS) decided to put a nice tall mixer tap in that has reduced the head to the point that the pressure is only good when the tank is completely full.
Otherwise run the hot and cold in the bath for a tank full, it could be an air lock although chances are the water would come out "lumpy" (in wierd pulses).

[jshell]

Air locks.

Run a piece of hose from the mains supplied cold kitchen tap to the hot tap and reverse flow until clear - or use a water filled piston style plunger to force water up each tap until air is cleared.

[Ferg]

jshell said:

Air locks.

Run a piece of hose from the mains supplied cold kitchen tap to the hot tap and reverse flow until clear - or use a water filled piston style plunger to force water up each tap until air is cleared.

But suppose the airlock is in the cold feed to the cylinder as is most often the case...?

[-Z-]

All sorted now. Nice bloke came round and sorted as suggested here from the kitchen sink. To be fair I did try this but he had a little rubber chamber which fitted over the end of the tap, giving more space to flow back.

He only charged £20 too

http://www.kenwhiffinplumbingandheating.co.uk for anyone that needs a good plumber in Essex.

[Deva Link]

Thanks for letting us know.