Locating blockage in finished underfloor heating.

[FisheryCottages]

Our new home has some underfloor heating. loop is not working although the plumber says there is reduced flow. He suggests a kink or blockage in part of the pipework and that the whole, finished floor has to be dug up. Everything is finished with heavy flagged floor in place.

Would be grateful for any ideas that may allow us to locate the restriction. One suggestion is to drain, attach a compressor and listen with a stethescope. Haven't tried yet but will try anything other than rip up the whole floor. Anyone got a trained beetle?

Thanks for any help or ideas.

 

[MANDATE]

Don't you think this could be an 'air lock' that can't be moved along till it can escape. If it is long loop where it fills from both ends then you could have a large amount of air trapped within. The normal pump can't push it along in my opinion because it just compresses the air more and it needs the resistance removing on the return side.
Is it possible to remove a radiator, then open the valve on the return side and run off a bucketful or two of water allowing any trapped air to move along and escape.
Can this heating loop be isolated from the rest of the system so you have access to both ends (inlet & outlet) I'm thinking it's like a radiator. Can you apply mains pressure at one end and allow it drain away at the other end and then reverse the procedure.

 

[PEDANTICVINDICTIVEMAN]

If all else fails do away with it and fit a radiator.

 

[Rincewind]

You should be able to disconnect loop from the heating manifold and run a hose pipe thru that section. If its a long loop the chances are quite high its an air bubble. need to flush it for a good 5-10 minutes then reconnect. Also shut down all other underfloor circuits and rads to force water thru loop, then re-balance system. Depends on ufh system you have, some manifolds are more user friendly than others.