Blocked pipe?

Mike Davies

I have an open vented fully pumped central heating and domestic water system - about 10 years old.

Having removed a radiator during decorating I discovered system did not refill from the feeder tank. Assuming an airlock I drained down the complete system but the feeder tank stayed full.

Still assuming an airlock I refilled the system under mains pressure at the drain point - this to move the airlock. The system refilled and water came out of the vent pipe into the feeder tank. I then sealed the vent with a gate valve to force any air or blockage back into the feed tank - but the system held mains pressure.

The design is a circuit of heater to pump to radiators back to heater. The feed tank and vent pipes are connected in a H formation the lower part of the H being part of the system and upper being the vent and feed pipes. The pipes connect about four inches apart and just before the pump. There are no gate valves between this connection and the tank for both the feed pipe and the vent. Unless there is a non-return or one-way valve somewhere, I cannot understand why the water does not push back up the feed pipe unless it is blocked. The pipe work is straight except for a couple of 90-degree bends and visible.

I have never had a pipe block like this before and I am still looking for other possible solutions before pulling the joints to have a look.

PS I have repeated process several times from different drain points with the same results.

PPS the rumour that Saddam was hiding in there is now proved false.

David Sutton_3

plz post a picture

of the system and the radiator you removed,,TY