Changing a lockshield on a combi boiler system

[kevg]

I've got a combi boiler system (valliant) which was fitted about 18 months ago. Recently took a rad off to redecorate but when coming to put it back on and open the lockshield it weeps. I've tighten the nut underneath and packed the gland but it still weeps so I want to change it.

I thought by closing the isolation valves on the flow and return to the boiler and then opening the valve to release pressure this would create a lock I need to change it but there are no isolation valves on any pipes under the boiler. SOmebody said about an auto air vent but have no idea what this is and where it comes into the equation.

Any help appreciated thanks

 

[newbie1]

you will have to drain it down

 

[Winston]

U,mm depends mate really if you close the trv on the rad turn boilel off and take some of the pressure off the sytem you could get away with it. But if in doubt drain it.

 

[newbie1]

even by isolating the valves at the boiler its a sealed system under pressure and will **** out if you undo the valve
you will have to drain down to replace

 

[stevetheplumber]

even by isolating the valves at the boiler its a sealed system under pressure and will **** out if you undo the valve
you will have to drain down to replace

with experience and subject to location you can do quick swops by shutting of boiler but for an amatuer id just drain it if you close all radvalves first it will be quick to refill

 

[newbie1]

with experience and subject to location you can do quick swops by shutting of boiler but for an amatuer id just drain it if you close all radvalves first it will be quick to refill

confused steve how will you stop the water coming out as even by isolating the boiler the system will **** out as soon as u undo the valve??

 

[stevetheplumber]

confused steve how will you stop the water coming out as even by isolating the boiler the system will **** out as soon as u undo the valve??

you let some drain and it will hold up like using bungs not reccomended on white carpets
most of the time you can turn carpet back and dust sheet

 

[Plumbstar Tom]

just drain it if I was you. Customers dont like to see water coming out

I would take the time to put iso valves on tho for future maintenance

 

[RoryD]

You don't have to drain down mate. Blow the pressure off the chb...completely. It is said that if you close the auto air vent off it is like bunging with a system boiler, I've never done it. Plenty of covers /absorbants around the pipe... undo and snatch it. With the pressure off there'll b a little water but be cool it's very little all under control. I've done it many times

 

[justlead1]

Hi I am with Rory on this one. The average DOC lets more water on the floor than changing a valve on the average combi system live. Providing it anit Blenheim Palace. I would open PRV to release pressure, isolate rad both ends crack valve union, drain in to baking tray (found in oven) Check compression fitting is compatible with existing on pipe and turned off, make sure systems cold (just in case, it burns) undo faulty valve, holding nut between fingers or mole grips on pipe at low level.(in case it slides down pipe and through large hole in floor board) Then wip it off and new on double quick. No Drama. and it extends a plumber life. As apposed to sitting about for hours draining, filling and putting additives in system.

 

[stevetheplumber]

Hi I am with Rory on this one. The average DOC lets more water on the floor than changing a valve on the average combi system live. Providing it anit Blenheim Palace. I would open PRV to release pressure, isolate rad both ends crack valve union, drain in to baking tray (found in oven) Check compression fitting is compatible with existing on pipe and turned off, make sure systems cold (just in case, it burns) undo faulty valve, holding nut between fingers or mole grips on pipe at low level.(in case it slides down pipe and through large hole in floor board) Then wip it off and new on double quick. No Drama. and it extends a plumber life. As apposed to sitting about for hours draining, filling and putting additives in system.

i never touch a prv unless in desperate once opened the feckers alway drip for me

Hi I am with Rory on this one. The average DOC lets more water on the floor than changing a valve on the average combi system live. Providing it anit Blenheim Palace. I would open PRV to release pressure, isolate rad both ends crack valve union, drain in to baking tray (found in oven) Check compression fitting is compatible with existing on pipe and turned off, make sure systems cold (just in case, it burns) undo faulty valve, holding nut between fingers or mole grips on pipe at low level.(in case it slides down pipe and through large hole in floor board) Then wip it off and new on double quick. No Drama. and it extends a plumber life. As apposed to sitting about for hours draining, filling and putting additives in system.

but you are right about DOC's though even the sealed ones leak as you have to open the gland nut to get any flow thru thats assuming the washers not stuck

 

[REDSAW]

prv open 2-3 times and they require replacing, experience.
drain down do it properly and charge for it.

 

[paul H]

drain down the system as needed dont cut corners
WHAT COULD POSSIBLY GO WRONG NOW !

 

[justlead1]

Hi Cutting corners depends of who draws the box.

 

[stevetheplumber]

Hi Cutting corners depends of who draws the box.

more to do with how much the box is worth

 

[justlead1]

You got it in one. I get bored easy, cant wait to spend it.

 

[smoggs03]

dont touch blow off just drain from the said valve (usually just till pressure is lost) and snatch it ( a rapid swap) job done... i've done stop taps using snatch method.