air lock or blockage?

[TerryWaite]

went to a job today where problem was hot water was just trickling out of the taps. Hot water is from an indirect cylinder, Y-Plan, upstairs, tank in loft.

I opened hot kitchen tap, water comes out for 20 secs then dies. Upstairs hot taps the same, possibly even worse. All cold taps in the house are ok, they are mains cold water.

I am suspecting an air lock but is there anything else it could be? I tried to bridge between the hot and cold taps with some foam insulation and then blast it through but i couldnt get the full pressure through the lagging and this proved unsuccessful.

I went upstairs to check the storage tank, it was full, float valve working ok, i put my hand in down to the bottom to check for sludge, there was not much, and the outlet seemed completely clear, you could get your finger in and it felt clear.

I am going back tomorrow as it was getting late, I am going to connect the mains to the hot downstairs under the kitchen sink and try and blast it through properly, my question is, is there anything else at all it could be or is there a chance that this wont clear the air lock (if it is an air lock which i suspect it is)?

Another thing of note, there doesnt seem to be a cylinder thermostat fitted, the hot water coming out of the taps is absolutely steaming, would this cause any excess scale/blockages???

Any opinions mucho appreciado

thank you

John

 

[hammers4spanner]

stick wet vac on hot nearest cylinder see what happens

 

[PlumbBobBob]

i agree try to suck the blockage/air lock out

 

[dontknowitall]

I had a job a few months ago where a wasp nest was removed from the loft. A few months later later the water slowed to a trickle.

Many of the beasts had landed in the cistern (not covered that well) and they had broken down and the abdomens had sunk and been drawn down to the taps. After clearing all the taps, everything was hunky dory.

 

[jepplumb]

Try checking the 3 port valve and see what position its in.
It controls the flow of the heating and hot water . It could be stuck or a electrical fault on the motor???
Why on earth you trying to connect the mains onto the hot water i dont no???????

 

[hammers4spanner]

Try checking the 3 port valve and see what position its in.
It controls the flow of the heating and hot water . It could be stuck or a electrical fault on the motor???
Why on earth you trying to connect the mains onto the hot water i dont no???????

read the o.p bud !

 

[diamondgas]

Try checking the 3 port valve and see what position its in.
It controls the flow of the heating and hot water . It could be stuck or a electrical fault on the motor???
Why on earth you trying to connect the mains onto the hot water i dont no???????

Re-read the original post jepplumb ... if you still don't know then you'd benefit from additional system design training IMHO TerryWaite has a gravity domestic hot water flow issue, little to do with the heating circuit? Sozz like!!!

 

[TerryWaite]

jepplumb i was connecting the mains to the hot water temporarily, to use the higher pressure to remove the air lock, its a fairly common thing.

the 3 port (or 2-port) valves do not pass any domestic hot water through them. they pass central heating water through them, which indirectly heats the DHW.

Hammers4Spanner and Steveb - thanks alot wet vac would probs be best option, but I dont have one

anyone ever come across a cylinder with no cylinder stat before too???

 

[diamondgas]

If all taps effected then trace back to the tee before all take offs Terry... Could be cold feed or main draw-off blockage first thoughts?

 

[hammers4spanner]

I came across one that was on the floor of cylinder cupboard before on routine service , said to tennant about it and got the usual grunt of dis interest . fixed it back into place a syou would .

 

[dontknowitall]

Many cylinders without stats out there and quite a few with some sort of thin red anorak draped over them too.

 

[diamondgas]

anyone ever come across a cylinder with no cylinder stat before too???

Loads but they were gravity circulation TerryWaite ...... Doesn't have anything to do with domestic supply to the hot taps though............? Sounds like an airlock/blockage in the feed/soply to the taps ... either air or physical IMO

 

[TerryWaite]

thanks diamondgas my thoughts exactly.... only problem is, where do i even start breaking joints, ill flood the gaff if i break any in the cylinder cupboard to try to check for full flow rate

as it is not rusty heating water id be more inclined to think air lock rather than blockage, do you ever get blockages on cylinder cold feed pipes?

 

[jepplumb]

my bad:hanged:

 

[jepplumb]

i didnt read it to good . But i didnt no you can connect the cold to resolve the problem..

 

[PlumbBobBob]

yes it's a common way of getting rid of airlocks.

 

[TerryWaite]

im always pecking peoples heads on here asking them stuff, but i have learnt an awful lot on here, i also try to give little bits of advice now and again myself if i feel i am knowledgeable on a certain topic, but more often than not, its me asking!! cracking forum though some clever people on here.

 

[jepplumb]

learn something new every day.

 

[REDSAW]

personally my first point of call is straight to the cylinder cold feed for blockage in the base.
i rig up a hose and shove it down the cold feed via the tank with the hot bath tap fully open.
try that.

 

[diamondgas]

Known of the obvious cold feed iso valve snapping internally ...... NO flow! Bit of insulation floating top of cylinder blocking off main feed! ... Crud got into CF blocking entrance to cylinder ... had a piece of what looked like a rubber pump washer lodged in the vent off feed tee restricting flow to taps ... Thing is you need to quiz the custard as to whether this is something new or inherent IMO .... you could be chasing a symptom you haven't caused?

 

[PlumbBobBob]

this is why you have to interrogate the custard before you start lol

 

[REDSAW]

'fry the mother'

 

[hammers4spanner]

Presume you have stuck your head in the loft to see if the ball valve is not sticking and enough water in tank?
You'l be alright as long as you start with the basics , can get bit messy sometimes tho with blockages .

 

[Paulus]

thanks diamondgas my thoughts exactly.... only problem is, where do i even start breaking joints, ill flood the gaff if i break any in the cylinder cupboard to try to check for full flow rate

as it is not rusty heating water id be more inclined to think air lock rather than blockage, do you ever get blockages on cylinder cold feed pipes?

I've had more than one where the hot water flow has been fine for years, then suddenly dropped to nothing. On all occasions it has been a lump of insulation in the cold feed to the cylinder.

 

[mountainman]

I found a similar blockage which turned out to be a decomposed pigeon (I think) and on another occasion a piece of eroded mortar which caused an intermittent blockage.