Bath running out of hot water!

[davey72]

Hi first post on this forum and hope someone can kindly help me.

My partner ran a bath last night, the hot water filled the bath about half way then tap went to a trickle and eventually stopped.
No hot water at all in any of the other taps in the house.

I have forced water into the hot water pipe by taking off the cold water pipe from the washing machine and looping it into the hot water pipe. It seemed liked an air lock when i ran the hot water again, lots of spurting but water soon flowed and became hot again. Problem solved..or so i thought , just ran bath this morning and the same thing has happenned!

Anyone any ideas please?

We have conventional gas boiler (not combi) and hot water tank in airing cupboard if you need that info.

I'm definately not a diy'er so please keep any solutions as simple as possible!

 

[picasso]

If you go into your loft and look in the big tank you will probably find the ballcock is stuck, put a new one in as they arent that expensive (or get your plumber to do it)

 

[JohnD]

How long has it been doing this? Have any plumbing changes been done since it worked properly? Had you been running other taps (hot or cold) before or during running the bath?

have a look in the cold water tank that feeds the cylinder, see how fast it fills up and how big it is.

It will have a ball-valve in it like you find in a WC cistern.

At a guess, the tank is not filling up as fast as the bath taps run (bath taps can easily deliver 5-10 litres per minute each, and a bath holds about 100 litres)

There may be various causes for slow filling, such as faulty ball-cock; low mains pressure; multiple taps running; a service valve partly shut (some people do this deliberateluy hoping to reduce noise); poor pipework design including restrictions such as ball-o-fix valves, flexible hoses, multiple elbows.

In the meantime you can try filling the bath up slower, e.g. by running one tap at a time, and waiting until it has stopped refilling before you turn the tap on..

 

[davey72]

its done this once before , many months ago and fixed it the same way by blasting water into the hot water pipe by washing machine.
To be fair we only use the shower and this is the first time we have run a bath since! No taps are turned on during or prior to filling bath .
I will venture up into the loft now and check on ball valve.

thanks for your help so far

 

[davey72]

Just had the same problem again (we dont use bath very often just showers)
bath got 1/4 full only then hot water tap ran dry, then air lock again.Went into loft, cold water tank filling up ok, ball cock valve not blocked.
Eventually the air lock cleared (next morning) but still cant see why we are running out of hot water when just running a bath, no other taps are on.


Anyone any ideas?

Is there a problem with the hot water tank in airing cupboard?

 

[warmadmax]

could it be a blocked vent pipe to the cold water tank??

 

[JohnD]

no

it is because water is being drawn from the tank faster than the ballcock is filling it.

go and stand by the tank with a torch while someone runs a bath, and see.

you have not mentioned a shower pump, or what size the tank is, so I wil start by guessing the ballcock is just dribbling out, in which case change it.

if someone else is running taps at the same time that will make the problem worse.

Also have a look in the tank for blockages due to insulation, limescale or drowned rodents.