Conventional boiler overflow issue.

[icemancomeths]

Reight then, I have solved the problem and it was simply pot luck.

The reason it was overflowing was because when I ran the taps, water flowed into the cold water tank through the codensation pipe not the valve. This only happens when BOTH bath taps are run on FULL.
So it seems the pressure from the cold water tap is much stronger than the hot water tap and forces it up to the cold water tank. Crazy.

Does this mean the tap is knackered? I have turned the stopcock half closed to release the water pressure and this helps.

Problem: The water level drops below the overflow level but it seems to continue to SUCK the water out of the overflow and the level remains at the bottom of the 90 degree pipe.

 

[helpsy]

Non return valves?

 

[icemancomeths]

Non return valves?

I doubt it has them, its a right bast*rd to get to the pipes though.

 

[kay-jay]

stick it anywhere, water dont compress. airing cupboard will do

KJ

 

[icemancomeths]

Is it safe to let it only flow in one direct?

 

[kay-jay]

right then
firstly your taps are not knackered, its just uneven pressure supplies. from what you say it must be a mixer tap.

fitting a non-return valve (check valve) is the way to remedy this problem. it needs to be fitted anywhere on the hot (weaker pressure) distribution pipework. because as i said before water does not compress. so it can go under the sink in question or it can go on pipework under floorboards (make sure its easily accessible tho) basically any position between the sink in question and the airing cupboard.

if you decide to put it in the airing cupboard....what you should see is a pipe leaving the top of the cylinder vertically then turning 90degrees onto the horizontal then a tee piece one axis horizontal this is the hot water distribution pipe and you can fit the valve on here. the vertical axis from the tee piece is the vent pipe which goes up to the cistern which is overflowing. as the vent pipe is a vital component of the hot water cylinder safety by providing somewhere for expanded volume of water to go in the event of a thermostat failure...YOU MUST NOT FIT A NON_RETURN VALVE HERE there must be an unimpeded route from the cylinder to the cistern.

if your pipework sounds a little different its ok, just probably an old installation, just make sure that the route to cistern is clear and fit the valve on any of the hot distribution pipework.

close to the cylinder is a good bet as it will allow you to add additional mixer taps to other sinks without additional check valves because it provides a non-return route for everything downstream, whereas if you fit the valve below the sink in question and add mixer taps to another sink you will need an additional valve as this problem will re-occur.


hope this clarifies things


KJ

 

[icemancomeths]

right then
firstly your taps are not knackered, its just uneven pressure supplies. from what you say it must be a mixer tap.

fitting a non-return valve (check valve) is the way to remedy this problem. it needs to be fitted anywhere on the hot (weaker pressure) distribution pipework. because as i said before water does not compress. so it can go under the sink in question or it can go on pipework under floorboards (make sure its easily accessible tho) basically any position between the sink in question and the airing cupboard.

if you decide to put it in the airing cupboard....what you should see is a pipe leaving the top of the cylinder vertically then turning 90degrees onto the horizontal then a tee piece one axis horizontal this is the hot water distribution pipe and you can fit the valve on here. the vertical axis from the tee piece is the vent pipe which goes up to the cistern which is overflowing. as the vent pipe is a vital component of the hot water cylinder safety by providing somewhere for expanded volume of water to go in the event of a thermostat failure...YOU MUST NOT FIT A NON_RETURN VALVE HERE there must be an unimpeded route from the cylinder to the cistern.

if your pipework sounds a little different its ok, just probably an old installation, just make sure that the route to cistern is clear and fit the valve on any of the hot distribution pipework.

close to the cylinder is a good bet as it will allow you to add additional mixer taps to other sinks without additional check valves because it provides a non-return route for everything downstream, whereas if you fit the valve below the sink in question and add mixer taps to another sink you will need an additional valve as this problem will re-occur.


hope this clarifies things


KJ

Perfect and thank you, appreciated 🙂

 

[stevetheplumber]

have you had any taps changed recently especially in th kitchen ? a lot of modern mixers are not bi flow and will back fill the tank via mains from tap going up the hot pipe