SD

Ok here's the story. I'd appreciate some advice on what the problem might be.

Yesterday morning I washed my hair and thought the hot water pressure was a 'little' low. Yesterday afternoon the hot water taps in the house (13 year old house - economy 7 hot water system) were fine on full opening, but after a few seconds lost pressure slowly until the flow of water practically stopped. Then it spluttered a little, then it came out, but very very slowly. When you turn off the tap you can hear the pipes in the house between the tap and the loft filling back up with water again. (I think). Cold water pressure is fine, no problem. Leave the tap for a minute or so and turn them back on and there's full pressure again but you lose that after a few seconds.

The system is a standard electrically heated storage system from what I can see. Cold water tank in the loft, and hot water tank/heater in the airing cupboard in the front bedroom.

Here's what I noticed:

1) The top of the hot water tank is hot, so it's definitely full.
2) There's a pipe going from the base outlet of the cold water tank in the loft to the hot water tank. This has a stop **** on it. When the hot water is just dribbling out the taps, stopping the stop **** makes no difference to the flow rate, it just continues to dribble out.
3) The cold water tank in the loft is full, and filling fine.

Other than that though, I'm at a loss. As I understand it the pressure from the cold water tank in the loft pushes the hot water out the hot water tank and out to the taps, right? So this is how the pressure works in the system? I can't see any pumps anywhere. (House has electric heating, so no central heating to confuse the issue).

As far as I can see there either must be a blockage in one of the pipes, or in the hot water tank. Am I right? Where else might the problem lie?

Any help much appreciated. I'm struggling to think what the problem might be, and how to resolve it.

Ta,

Simon.

[Edited by SD - 6/27/2002 8:53:41 AM]

alcazar

iTrader: (2)

Had something similar at bro in law's. He was stumped.
Go up in loft and watch what happens as someone turns on the taps.
If they've turned the taps on full you should see the level in the cold tank start to fall, and as it does so, the ball valve will fall, opening the ball-****, and allowing water to enter.
Keep watching. The level should fall slightly, and the ballcock should remain open, while water continues to pour out of the taps downstairs. Get helper to tell you when the flow starts to drop off at the taps. What's the ball-valve doing?
My guess is that you've a blockage somewhere between the cold tank exit, (can you see it in the cold tank? Is there anything obvious blocking it?), and the entry to the hot tank.
If the blockage is not obvious, tie the ballvalve in the up/shut position, turn on the hot taps, and wait for the cold tank to drain. Now disconnect the feed from the bottom of cold tank to bottom of hot tank, AT THE TOP ONLY!!!!
Try poking a piece of curtain wire down it. Is there a blockage, or does it go all the way (take measurements to check)? blockages are common at the right angled bend into the hot tank,persevere with the wire until you're SURE it's there.
If you find a blockage, you'll have to drain the hot tank now via the drain-off tap somewhere at the base of the tank, into bowls/buckets etc, a ball-aching job. Then disconnect the cold feed pipe at it's lower end,(cut it if necessary), remove blockage, reconnect or replace cut section with fresh piece of pipe and compression joints, refill, and away you go.
About half a day's work, but a LOT less than a plumber will charge you, and easier than working on a modern car!
Hope this is of help

SD

Wow, thanks alcazar for that comprehensive reply! I'm at work now but I'll try what you suggest when I get in...

Will let you know

Simon

Jolly Green Monster 2

I agree with Alzcar, when I replaced my hot water tank recently the pipe to the top of the hot water tank was reduced to about 3mm's by limescale in the pipe.
Are you in a hard water area? the tank heats the water sitting in the pipe when no hot water is being used and the limescale sticks to the sides of the pipe just like in the kettle....
I would place my bet on that pipe / bend at the top of the hot tank.

Mine was so bad that I put the biggest drill I could in the pipe and drilled the channel bigger. But couldn't empty it totally so added it to my long list of jobs for one day... replace that bit of pipe.

Good luck

JGM

alcazar

iTrader: (2)

Also agree with JGM2- check the outlet pipe while the tank is empty, but be a bit careful drilling it out if you can't recover the debris. It'll end up knackering your taps (which is better than it tapping your Knackers!!)

Jolly Green Monster 2

LOL at Alzcar.

JGM

Mog

Being one of the so called expensive plumbers here is my 5 bobs worth or 5 squid
1.It is very unlikely to be limescale if you suddenly lost pressure as limescale build up is very slow.
2.Limescale only occurs badly when water is heated above 60 degrees,so it is worth checking the immersion heater stat.
3.Is only one hot tap affected or the whole house.
4.Has the hot water system been drained recently.
5. The most likely reason is an air lock in the stopcock/gate valve.
6.However I have come across on a few occasions the plastic disc at the bottom of the cylinder(part of the sacrificial anode) coming off and floating up and blocking the outlet.

More suggestions can be given based on your answers

£50 can be sent by BAC's to my bank

Regards
Mog

scooby nutter

Being one of the so called expensive plumbers(ME TOO)

Sounds like blockage or air lock.But air locks only really happen if the hot water was switched off recently!

Anyway a little trick,bit naughty but ssshhhhh!!

Get some hose,attach to cold tap securely.Attach other end to a hot tap securely(presume they are old taps)open hot tap fully,then open the cold to backfeed the hot which should clear the air lock(if thats what it is ,we never get scale here in blackpool)

Cheque payable to D.Parkinson,Thanks


also forgot to add,whats on top of your domestic tank?As we have had blockages with fiberglass(roof insulation),this falls into tank and blocks the pipe somewhere!!!A right B******

[Edited by scooby nutter - 6/27/2002 7:28:39 PM]

alcazar

iTrader: (2)

LOL at Mog and Scoobynutter, told you plumbers were dear if they can afford to run Scoobies. (Tongue in cheek mode).

SD

Guys - thanks for the comments! I've just got in so I'll try a couple of the things now to see if I've any luck.

Simon.

RON

I'm no plumber, but could the thermostat be busted? thereofre the hot water is getting too hot and causing said air lock!!!!!
Like I said, no plumber, but if it is the problem I'd like the £50 please!!!

mattstant

ooh naughty scoobynutter
I am a water inspector and you are now fined for flouting byelaws regs.

Or


50 squid to keep quiet

druddle

Not sure if its related but i had a problem with water pressure and it turned out to be the ball **** on the header tank in the loft. I lived in a hard water area, and the hinge for the ball **** got clogged with scale, so the ball **** didnt fall with the water level and hence never filled up.

Dave

scooby nutter

mattstant,

Your cheques in the post