The system is a sealed one which only does the central heating.Re changing a radiator valve(not thermostat one), how do you blank the inlets to system and where to do it.?If you are lucky, your radiator will have isolating valves on both the inlet and outlet. If not you will need to empty (drain-down) the whole system. This is not as daunting as it may sound. First, turn the boiler/heater off. Find the low-level drain point (usually near to a back or side door) and lead a length of hose pipe from the drain-off point to outside the house. The %26quot;header%26quot; tank for the system will be in a high part of the house (roof-void/loft/airing cupboard) Turn off the outlet valve/tap if it has one or place a piece of wood or garden cane across the top rim of the tank and tie the ball valve arm up to this to stop any water delivery into the tank. Finally open the low-level drain-off and when the water stops flowing from the hose-pipe outside, you can do what you like with the radiator. In case the water in the system has had a treatment additive make sure that none of it can fall onto any carpet or rug beneath the radiator - it will stain! When the job is done, untying the ball-valve or opening the outlet valve/tap will allow the system to refill. Don't forget the water treatment additive - your local hardware or builders' merchant will supply you with this. Good luck!Re changing a radiator valve(not thermostat one), how do you blank the inlets to system and where to do it.?There's an alternative to draining the system down - you can freeze the pipe below your radiator valve, and turn off the valve at the other end of the radiator, then you only have a radiator-full of water to deal with.
Make sure the radiator is cold before you start, and that the new valve is an exact replacement for the old one so you won't waste time modifying the pipework!
Freezer kits are available at larger DIY stores in the UK or from specialist plumbers merchants and they save loads of time and effort. Briefly, you wrap the pipe in foam lagging (supplied) then spray the can of freezing mixture in. The water freezes in a few minutes, and stays frozen for 20 - 30 minutes - plenty of time to swap your radiator valve, and if you're quick you won't even need to worry about the water in the rad. Just put a pan under the rad connection and work quickly!
Another bonus - as you will have lost almost no water there's no topping up to do (but vent the air from the top of the rad just in case).Re changing a radiator valve(not thermostat one), how do you blank the inlets to system and where to do it.?No need to blank any inlets off as the %26quot;mains cold water filling loop%26quot; will already be in the off position. If it wasn't you'd have crazy system pressure and could well be heating up the mains cold water supply if the non return valve was a bit duff !.
For a belt and braces approach you can disconnect the loop nearest the incoming valve.
Filling up is just a case of turning on the taps on the filling loop and raising the system pressure to 1 or 1.5 bar (cold) then venting the radiator - then topping up the pressure to 1 or 1.5 bar.
Job done.
PS. The loop is generally a braided flexible pipe close to the boiler
