hot water cylinder question, can one of you great people help.

[dgee2040]

Hi, im trying to turn off my hot water to change a tap washer, i have a dimplex hot water cylinder. i have attached a photo of it, the two valves on the right are labled to turn off hot and cold water, the cold water valve works instantly no problem with that. the hot water one doesn't stop the water completely i went to the kitchen to try and drain the remaining hot water from the pipes to discover that it just keeps on running at lower pressure and spluttering. but all the other taps are are dry in the house. it seems that it only has enough pressure to run through one tap? do i have to completely empty the tanks?
can anyone help me thanks i really appreciate it

 

[Best]

Those gatevalves are renowned for letting water past.
If you can find the mains stopcock that supplies your home, then turn it off and it should turn both the cold & hot off. (Your unvented cylinder is supplied from the mains).
There might be a valve near the cylinder, but otherwise find your stopcock perhaps in kitchen or a cupboard somewhere

 

[dgee2040]

ok i see, i have a tank in the attic. does that only supply the cold water taps in the house?

 

[ShaunCorbs]

Is it a small tank eg about 11/2 long by a foot wide ?

 

[quality]

the tank in the attic will feed the heating/boiler circuit

 

[dgee2040]

no its bigger it looks just like your average cold water tank?
so those two gate vales in the picture they are labeled to turn off hot and cold to all appliances are those pipes mains fed? so if i turn off the mains will it turn off water instantly? really appreciate the help lads thanks

 

[dgee2040]

i turned off the mains stopcock, it didnt stop the hot water. so it possible the tank could be gravity fed rather than mains fed? im in ireland and the water pressure in my area is very bad.

 

[ShaunCorbs]

When you run the hot water does the loft tank fill ?

 

[dgee2040]

yes it fills i often hear it after i shower?

 

[ShaunCorbs]

Any chance of a pic of the bottom half of the cylinder ?

Edit just seen the gate valves are labelled turn the one hot off you might need a pair of grips to totally turn it off,

Should stop then give it a /16 more of a turn

 

[dgee2040]

i will try that. do i need to take of the handle to turn it with the grips. is there a chance of it breaking off and leaking on me? so is my system a gravity fed cylinder? thanks shaun

 

[ShaunCorbs]

No just use the grips on the red handle part

And with gate valves yes but not to leaking

Looks like a unvented thermal store but fed from a gravity source

 

[Ric2013]

As Shaun says, gate valve could break. Unlikely to leak, but then will be jammed shut. You'd then need to replace it, but that is where you are anyway if it doesn't work.
On a lateral way of thinking, if it's running at a lower pressure, you could potentially leave the lowest tap running and change the other washer above. Waste of water, but hey ho.
If the flow is slow enough, you could even change the tap washer downstairs with it running through the tap you are working on. I have done this before I became a plumber (I now have an internal pipe bung for these occasions).
If you have an assistant that could hold a hand over the tap body while you play with the removed mechanism (to ensure the water runs down the spout as usual) that could be handy. Try to catch the hot water in buckets for a bath after?

 

[dgee2040]

thanks lads i tried the above and got it closed off. the gate valve is sticking etc i think its fecked. got the washer changed. thanks all for taking the time to help.

 

[ShaunCorbs]

Did you open the gate valve back up ok ?

TBH best get it changed for a full bore lever valve

 

[dgee2040]

yeah it opened up although it sounds like its on its last legs. so i think i will get that changed. thanks again shaun.

 

[sammathias]

plug the outlet of the tank in attic, jobs a good'un! suprised that gatevalve didnt snap closed. terrible valves.

 

[Ric2013]

Gate valves I feel have an undeservedly bad reputation. I have used ones that are probably 5o years old and working, and ones that have failed entirely in 20. Buy cheap: buy twice.

 

[Moffski72]

An unvented thermal store?
Really?