Water from a vent pipe

[doitall]

Another small point for you to think about as its Sunday.

Raising the system pressure 0.2bar with the backflow from the mains, in affect raises the storage tank 1m.

In theory the water level in the tank is now higher than the vent.

 

[gasmanuk]

Ok my take on the situation whilst trying to sift through all the bitching was that the guy had warm water in his header tank his vent was slightly low in his opinion and I think everyone agreed that his shower his passing.

My thought was that if the water was coming from the vent

1 He would see it and,

2 It wouldn't be warm

Did he say he could see water coming from the vent???

 

[doitall]

Yes he has water coming from the vent.

There will be a blend between the hot and cold depending on the amount of backflow.

I would favour the new basin taps letting by actually

 

[Softus]

Yes he has water coming from the vent.

There will be a blend between the hot and cold depending on the amount of backflow.

I would favour the new basin taps letting by actually

Not a chance - basin taps mix the water after the two, independant, valves.

Shower valves, if faulty, allow cold water to meet hot water before the single valve, which is why it's particularly important always to ensure that shower supplies are balanced in terms of pressure.

 

[SteveStrat335]

I've been following this topic with interest , and although I am a habitual lurker, I wanted to suggest this possibility:-

It seems to me there is good chance that when the shower/tap is first turned on, there may be enough back pressure in the mains to force the water up the vent. Once this has stabilised, then it would only flow as far as the cold feed.

So in effect you could both be right!

OK flame me

 

[doitall]

Not a chance - basin taps mix the water after the two, independant, valves.

Shower valves, if faulty, allow cold water to meet hot water before the single valve, which is why it's particularly important always to ensure that shower supplies are balanced in terms of pressure.

Some cheap mixer taps, are not Water Company compliant, and mix in the body not the spout, so every chance.

 

[Softus]

Some cheap mixer taps, are not Water Company compliant, and mix in the body not the spout, so every chance.

I didn't say that basin taps mix in the spout, I said that they mix after the independant valves.

A basin tap that mixes in the body, whether or not it's WRS approved, still doesn't mix hot and cold under any more than negligable pressure. This is the case for all basin taps, which is why the OP's problem isn't caused by a basin tap.

If you had a bath tap that is a combined filler and shower with a divertor valve, then it's possible for the resistance of the divertor/hose/spray to be such that the tank fed hot is defeated by cold mains, if the supplies are imbalanced in that way. If the resistance is sufficient then the mains pressiure can even force cold water back into the hot supply (which is a variation on the theme of this topic).

However, I'm not aware that the OP has a bath mixer/shower divertor.

 

[doitall]

If the resistance is sufficient then the mains pressiure can even force cold water back into the hot supply (which is a variation on the theme of this topic).

However, I'm not aware that the OP has a bath mixer/shower divertor.

That is what I think is happening, if you can still remember somewhere in this thread the OP said he has just had a new basin and shower fitted, any plumber worth his salt would have fitted a balanced supply to the shower, whereas in a rented flat he could have a mains cold to the basin.

Perhaps one day the OP will update us

 

[Softus]

That is what I think is happening, if you can still remember somewhere in this thread the OP said he has just had a new basin and shower fitted, any plumber worth his salt would have fitted a balanced supply to the shower, whereas in a rented flat he could have a mains cold to the basin.

I think this brings us roundly to a major point of agreement!

We both think it's the new shower valve, we both think the mains cold is backfeeding, and if we carefully tiptoe around whether or not it's coming out of the vent (and I'm NOT trying to restart that argument), then we disagree on nothing.

Teggs - put us out of our misery; pretty please?

 

[doitall]

But Teggs said it was coming out the vent if you want to plough back through, somewhere at the start.

And I don't think it is the shower, I still favour the Basin taps. and I could definately be wrong on that one

 

[ChrisR]

A basin tap that mixes in the body, whether or not it's WRS approved, still doesn't mix hot and cold under any more than negligable pressure. This is the case for all basin taps, which is why the OP's problem isn't caused by a basin tap

Had one 2 weeks ago doing exactly what the OP has. Newly dislodged scale (from gate valves) had collected in the new tap's spout filter/aerator gauze to block it sufficiently for the cold mains to go back up the HW pipe. Ie it isn't negligible pressure.

 

[Softus]

Had one 2 weeks ago doing exactly what the OP has. Newly dislodged scale (from gate valves) had collected in the new tap's spout filter/aerator gauze to block it sufficiently for the cold mains to go back up the HW pipe. Ie it isn't negligible pressure.

Ah, nice one - I hadn't considered a blockage within the basin mixer, dagnabbit.

 

[Gasman1015]

Recent repairs:

System boiler loosing pressure: Fault leaking coil in hot water cylinder, verified by leaving filling loop open, cold water tank overflowing and backflowing through cold tank outlet pipe.

Mains pressure 3 bar.

Water tank overflowing, customer recently fitted bristan shower unequal pressures, mains backflowing into gravity hot water, cold water tank filling through hot water vent.

Mains pressure 4.2 bar.

 

[Softus]

Water tank overflowing, customer recently fitted bristan shower unequal pressures, mains backflowing into gravity hot water, cold water tank filling through hot water vent.

Faulty valve, or was water coming out of the vent only when the shower was in use?

 

[doitall]

Recent repairs:

System boiler loosing pressure: Fault leaking coil in hot water cylinder, verified by leaving filling loop open, cold water tank overflowing and backflowing through cold tank outlet pipe.

Mains pressure 3 bar.

Water tank overflowing, customer recently fitted bristan shower unequal pressures, mains backflowing into gravity hot water, cold water tank filling through hot water vent.

Mains pressure 4.2 bar.

In your first example the cylinder was being pressurised with the mains water .

In your second example, which is the same as Mr Teggs, the pressure is outside of the cylinder.

That is the example I was trying to explain to Softus, probably not very well I should add.