Underfloor Heating Question

[Doobrey]

Hi guys,

Firstly can I say how helpful everyone has been on the forums over the last fews days. You have helped me replace a thermostat, replace a syncho motor and now I am asking for a little bit more assistance please!

I have underfloor heating that works of off 2 manifolds. (Picture attached). As you can see the bottom manifold sends out HOT water through the system, which is then split into the 5 zones in the house. These zones are all on the bottom floor of the house. I can control the zones independently using the valves connected to the manifold.

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• Doobrey
• 20 Nov 2009
• 5

If I open the valves the plastic pipes connected at the bottom all get hot (so that's positive)....

The issue I have is the return valve for one of the zones doesn't warm up - to be this indicates a blockage in the pipe. On the picture it's the first "Grey coloured" plastic pipe. Closest to the drain tap.

I want to "unplug" this plastic pipe and do a test from the hot side all the way through, to confirm whether there is a blockage in the pipe, or a fault on the return valve.

This next picture shows the other end of the manifold.

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• Doobrey
• 20 Nov 2009
• 2

Do I turn off the red taps prior to unplumbing the "grey plastic pipe"?

How do I push water through this system? I assume, turn off the rest of the valves, leaving the grey one open?

Any help would be much appreciated.

Doobrey.

P.S. Final picure of the other end of the system

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• Doobrey
• 20 Nov 2009
• 1

 

[Garfeild]

Where is the blending valve and pump etc?

 

[jackthom]

Is the zone in question actually being warmed at all as far as you can tell?

As a first step have you tried progressively closing the other zones so the flow is forced through this zone, to see if that helps?

There could be a blockage or the system may simply be in need of balancing.

 

[Doobrey]

Hi - the pump is in the airing cupboard upstairs. If you see my other post (search for Doobrey) you can see the installation diagrams.

There is a pump for the central heating, and a pump for the underfloor heating. The central heating (in my words) being the radiators upstairs.

Most of the other zones are switched off, yet the return pipe still doesnt get hot. Considering the temperature of the water is piping, I suspect a faulty valve or blocked pipe.

I know I have to replace a valve previously, but can't remember how to isolate the pipework to confirm whether water is flowing freely or not.

Here is a diagram of the installation..

View media item 16944 View media item 16945

 

[jackthom]

There is a red (gate?) valve to the right on both the flow and return main pipes. When these are both shut the manifolds should be isolated.

With all other zones closed down if you undo one of the pipes to the faulty zone and then partially open the red gate valve on the opposite manifold you should get water flowing through the zone. (onto your floor!)

Alternatively by opening the gate valve on the same manifold as the opened connection, you can check out each suspect valve in turn.

Buckets and cloths would come in handy.

 

[Doobrey]

Thanks all!

I will try it tonight. If the pipes are blocked, does anyone have any suggestions for clearing them? Someone must have done something similar before?

Doobs.

 

[Garfeild]

I would imagine mains water pressure ie hose pipe would be enough to blow out any blockage,or do as previously suggested shut both gate valves,disconnect one end of the pipe,and open relevant valve,should work unless the pipe is kinked somewhere,has the pipe in question always been cold or has it worked previously?