Help, very confused.

[jase158]

Hi All,

I have recently replaced the float valve in my cwst, because the old one was making too much noise, this solved the noise problem but now I am faced with the water going really slow after about 3-5 minutes of running it for the bath.

I have checked the cwst to see if it is going empty but this is not the cause. I am a bit puzzled as to why it would run dry.

my cwst is on the first floor and my bathroom is on the ground floor.

the only conclusion I can come up with is a blockage, there is little bits of dirt coming out, but why did it work before i changed the float valve and it works up to a point?

The water goes slow for about 30 seconds and then goes back to normal, this is happening twice when running a bath, so can become a right problem and isnt brilliant as I am a plumber and having this problem when people are visiting.

If it is a blockage, what can be done to clean the water (potable) pipes? apart from replacing.

 

[diamondgas]

How about the hand basin, does that do the same?

 

[jase158]

not tried it, will have a look.

 

[REDSAW]

debris has entered the feed pipe or air lock?.
turn cold supply off and empty tank. temp bung vent.
connect hose to cold tap and back flush the cylinder thru hot tap for a few seconds.
see what pushes out and clean out.

 

[jase158]

How about the hand basin, does that do the same?

the hand basin alone does not seem to cause it, however if I open the bath and sink at the same time then both run dry.

may I just add that it isnt the cold tap, it is the hot as the cold is off the mains (very old system) so it is coming from cwst, to the hwc, to the hot tap.

I am thinking that there isnt enough pressure when the cwst is half empty? so this is why it is slowing down so much, but unsure.
never heard of this before, I thought that as long as there was enough water to cover the hole there would be enough pressure, as the pressure builds up in the pipes? or am I wrong?

 

[REDSAW]

the feed pipes blocked,

 

[BLOD]

sound like an airlock to me - I'd follow Redsaw's instructions and see what happens

 

[diamondgas]

:iagree: most likely blockage in feed or air lock in domestic as already mentioned :iagree:

 

[secret squirrel]

Was it running dry before you changed the ball valve?

if so agree with the airlock or have you touched anything else which you may have broken?

 

[jase158]

no it wasn't running dry before the ball valve change. cheers evrybody, will look into it, very hard water round hear, the tank has got some limescale in it, could be some sort of blockage. cheers redsaw

 

[stevetheplumber]

if the cold is mains fed why would he have an airlock on the hot unless this plumber took so long to change the ballvalve someone run the tank dry

 

[armourer]

I would guess as you have changed the float valve, it now fills a lot quicker and the extra pressure/turbulance in the cwst has dislodged some muck/scale in the bottom and that has partially blocked the feed.

 

[Resolute]

Where is the HWC in relation to the CWSC?

 

[jase158]

HWC is directly below the cwsc, literally, 10-20cm below.
I am a plumber so it only took me 5 minutes, if that to change and in my house, so no water was used whilst doing the change.

 

[diamondgas]

HWC is directly below the cwsc, literally, 10-20cm below.
I am a plumber so it only took me 5 minutes, if that to change and in my house, so no water was used whilst doing the change.

Seems a weird co-incidence doesn't it?

Ever done the glass of water test? Can help you eliminate a few things ... With no taps on place the open-vent pipe in the glass of water. Shout to your missus to turn the tap on and see what happens to the water in the glass? If the vent sucks it out then your blockage/restriction is in the cold feed or cylinder before the open-vent tee. If the water level remains pretty much the same then it's in the pipework to the taps!

 

[jase158]

Seems a weird co-incidence doesn't it?

Ever done the glass of water test? Can help you eliminate a few things ... With no taps on place the open-vent pipe in the glass of water. Shout to your missus to turn the tap on and see what happens to the water in the glass? If the vent sucks it out then your blockage/restriction is in the cold feed or cylinder before the open-vent tee. If the water level remains pretty much the same then it's in the pipework to the taps!

What happens if you don't have a blockage?

 

[jase158]

"Seems a weird co-incidence doesn't it?"

what is?

 

[diamondgas]

Weird co-incidence is that you change the ball-valve & the tap stops working ... totally not conected by what you've described ..........

If it doesn't have a blockage/restriction then your taps would be working fine and you wouldn't be pulling your hair out .. Aaaand the water level remains steady/unmoved

 

[cobra]

try changing back to old float valve and see what happens ie then you could eliminate the new float valve for possible problems, then your only left with blockage or air lock

 

[cobra]

is isolation valve upstream of float valve fully open or maybe slightly blocked-unlikely but you never know

 

[BLOD]

Might be worth disconnecting the hot water outlet from the top of cylinder and looking for scale build up around there.
Come across this a few times and only takes a few minutes to check.

 

[REDSAW]

chronic irregation required mate