Anybody good with central heating????

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Ok im a gas safe registerd engineer,

When you over pressurized you r boile it sounds like you have burst the expansion vessel which is inside the tank, One side is compressed air witha rubber membrane in the middle and the central heating water on the other side, As you r heating heats up the water expands, pushes against this membrane which keeps the pressure similar to what it is cold or it will increase by a mximum 0.5 bar,

So what is happening now is you pressureize the boiler, turn on and the pressure increases as it heats up, with the expanded water not having anywhere to go it over pressurizes which causes the PSV (pressure safety valve) to lift and release water(as it did when it first banged), so this is where you will be losing water from, The chances are that the rubber seal inside this valve will be knackered as well as the vessel or might just be the valve.

The expanssion vessel is a tank inside the boiler, it will have a car type valve on the top depress this and make sure only compressed air comes out if any water comes out it is knackered, you can repressurize dit to 1 bar using a foot pump, depending on the boiler if its knackered you have to take the full boiler off of the wall to rplace it, the vessel themself range from £45 to about £185 depending on manufacturer and make,

The PSV is the 15mm pipe comming out of the boiler and sghould then exit through the wall and then bend back on its self, this might just be a drip, Pleas do not go to close to it when the Boiler i operating it could shoot out water at 3 bar and anything up to 100 degrees C, as water under pressure does not boil at 100 degrees so when its release it is warmer
 
andy mcd said:
Ok im a gas safe registerd engineer,

When you over pressurized you r boile it sounds like you have burst the expansion vessel which is inside the tank, One side is compressed air witha rubber membrane in the middle and the central heating water on the other side, As you r heating heats up the water expands, pushes against this membrane which keeps the pressure similar to what it is cold or it will increase by a mximum 0.5 bar,

So what is happening now is you pressureize the boiler, turn on and the pressure increases as it heats up, with the expanded water not having anywhere to go it over pressurizes which causes the PSV (pressure safety valve) to lift and release water(as it did when it first banged), so this is where you will be losing water from, The chances are that the rubber seal inside this valve will be knackered as well as the vessel or might just be the valve.

The expanssion vessel is a tank inside the boiler, it will have a car type valve on the top depress this and make sure only compressed air comes out if any water comes out it is knackered, you can repressurize dit to 1 bar using a foot pump, depending on the boiler if its knackered you have to take the full boiler off of the wall to rplace it, the vessel themself range from £45 to about £185 depending on manufacturer and make,

The PSV is the 15mm pipe comming out of the boiler and sghould then exit through the wall and then bend back on its self, this might just be a drip, Pleas do not go to close to it when the Boiler i operating it could shoot out water at 3 bar and anything up to 100 degrees C, as water under pressure does not boil at 100 degrees so when its release it is warmer
Click to expand...

Bloody typical init, we've sold the house and due to complete in 4 weeks and i stuff the boiler!!!
 
Heavy Breather said:
There's def a leak from the boiler, there is a damp patch underneath. Is there a bodge i could do that'll last a few weeks?
Click to expand...

drain it right down and dry area and put some chemical metal over a good patch (be sure to scoure the area with some course sandpaper before applying) has got us out of trouble a few times where we have had a old fasioned cast iron radiator (when the custumer is a tight arse never to get ourselves out of the ****e )
 
This is the first chance i've had to look at it since early sat. There's a leak from the Heating Circuit Pressure Safety Valve. Poured out as soon as i turned the boiler off just now and quickly slowed to a drip, wasn't leaking like this on fri.... could it be some crap in the valve???
 
hi ron i tend to think its the expansion vessel, attach a pressure valve to the valve on the red cylinder with the boiler off, it should be above 0.5 bar, if not pump some air in, then try the boiler, the release valve will be wet through it expelling water everttime its fired up, i had the same last christmas eve, it costs nothing to check it.
 
is there a red cylinder? and i aint got a pressure valve.........can i not just hit it with an hammer, i've lots in different sizes???????
And the bastard buyer is a surveyor, he's coming to do his own survey, thats fookin cheatin
 
johnlad said:
hi ron i tend to think its the expansion vessel, attach a pressure valve to the valve on the red cylinder with the boiler off, it should be above 0.5 bar, if not pump some air in, then try the boiler, the release valve will be wet through it expelling water everttime its fired up, i had the same last christmas eve, it costs nothing to check it.
Click to expand...

Hi John, Andy thinks the same, i've got the boiler diagram and it shows the expansion vessel to be at the back, looks imposs to get to without taking the boiler of the wall, and some thick get has boxed it in real tight under the stairs:(
 
Heavy Breather said:
Hi John, Andy thinks the same, i've got the boiler diagram and it shows the expansion vessel to be at the back, looks imposs to get to without taking the boiler of the wall, and some thick get has boxed it in real tight under the stairs:(
Click to expand...

be inclined to get the house like the tropics before he gets there, switch it off clean and dry it up and keep shtume .
be no differant than anyone else would do , i can think of 2 of our customers that have had that 1 pulled on them ;)
 
buckshot said:
be inclined to get the house like the tropics before he gets there, switch it off clean and dry it up and keep shtume .
be no differant than anyone else would do , i can think of 2 of our customers that have had that 1 pulled on them ;)
Click to expand...

Very tempted to do that, it don't leak nor does the pressure drop while the boilers on so it'll be running just fine when he gets here;)
 
The usual problen is if the pressure relief valve has opened it can cause the washer to split, or a bit of gunk can get wedger on the seating. Chuck some radweld in the system. you can get "propper" stuff for heating systems, but prob cheaper to get radweld from halfords. My mate uses it when he goes to jobs with a slight pressure drop says it works a treat
 
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