Hi i need to change thermostatic valve on my heatin system ive blocked of the vent& feed pipes with rubber plugs & pulled about two gaallons of water off. but it shows no sign of easing up. have i pulled enough water off or am i doing something wrong. thanks in advance.
rad valve
- Thread starter harrison_633
- Start date
You shouldn't need to get rid of that much water! How are you doing this?
Check that the rubber bungs are correctly inserted by watching the water level in the tank when you pull of the water.
Make sure you turn off the lockshield valve at the other end of the rad. (Make a note of how many turns to close so you can reset it to the correct position.)
If there is an automatic air valve on the system, this needs to be shut off.
Here's a pic of mine. It's the brass thing on the top of the vertical pipe next to the cylinder. You turn the cap on the top clockwise to shut the valve.
View media item 36821
When the bungs are in place and any valves closed you should undo the bleed screw on the rad. Water will come out but should stop fairly quickly as a vacuum is created in the system. It's then safe to disconnect the valve you want to change.
Bungs will not work if the water level in the tank is more than 10m (33ft) above the joint you want to disconnect. This is because the water pressure is then greater than the air pressure, so the vacuum will not be maintained.
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