Attempting To Flush Underfloor Heating System

[congresstart]

Hey all,
I have two areas that aren't getting heat, my googles seem to suggest an airlock/blockage of sorts.

I've attempted to flush the system through, see links below for actions taken:

Tank/Boiler - Open fill valve
Manifold

When draining this a tiny bit of water is flowing out but not much, have gotten the process wrong?

- Is it the lower drainage that should be used?
- Does the blue value need to be open and red closed?

Manifold levels need to be replaced as they are full of gunk

 

[Madrab]

With UFH systems, you don't really drain apart from the manifold, you run cleaner/biocide through it and leave it to work then flush through till clean.

The red and blue valves are the flow and return from the boiler and should be set shut unless you are looking to drain the rest of the system.

Re the flow meters, they should be fully open when using the cleaner and that should then get in there, if that doesn't work then most can be removed/disassembled and manually be cleaned out out, just go easy with them as they can be fragile.

 

[Rodders53]

From reading my UFH manifold stuff, Emmetti...

Close both valves Red and Blue.

One needs to remove the Actuator(s and replace with a manual knob that opens the individual UFH circuit/loop by depressing the pin... and the flow meter either fully opened (or maybe left at the balance flow rate). The knobs are navy blue and domed in my case.

Flushing is then done via the fill and drain connections at the other end to the manifold valves using mains water and a hose to input and the drain.

I'd be inclined to suspect an actuator not opening the manifold valve properly rather than an obstruction in the loops of the pipework; unless that has been eliminated.

May be worth reading your brand's website stuff?

Underfloor heating troubleshooting

Solve technical problems & troubleshoot your underfloor heating issues with our full range of online FAQs, or ask a Nu-Heat expert to help.

www.nu-heat.co.uk

 

[Madrab]

The other test would be to remove the actuators from the troublesome loops and check the pins are moving freely and then run the system.