Potterton Netaheat 10-16 will not refill

[NobbyD]

Hi

Drained, flushed and replaced a radiator in my vented Potterton Netaheat 10-16 CH system. The header tank filled ok but the pump doesn't appear to pump water around the system when the Boiler is turned on.

I turn on the boiler by turning up the main Thermostat, I can hear water initially move (gurgle!) inside the boiler and there is the sound of running water inside the boiler, but the Header Tank isn't draining to refill the radiators. It also sounds like a pump is working (once a second pushing water into the boiler?). The boiler front gets warm, but the main gas boiler hasn't ignited, so not sure why this is?

Bleed valves on the rads are open but no air is being expelled.

Any help or advice on refilling a Potterton Netaheat CH System welcome!
If you need any further info, please let me know.

Thanks
Neil

 

[45yearsagasman]

Your cold feed pipe is probably blocked at the point where it connects to the system pipework. Follow the 15mm pipe from the outlet of the exp tank and where it joins the system is where you need to investigate. If it is blocked then it needs to be cut out and cleared properly.

 

[NobbyD]

Thanks but pretty sure there isn't a blockage from the expansion tank. When flushing the system, the Expansion tank was filling and empying normally and after 15 to 20 mins of flushing the water running from the drain point was clear and the Expansion tank was still filling/emptying normally. The Expansion Tank ball cock was then tied up and the remaining water drained.

During the flush, however, the old downstairs rads filled and now when I try to bleed them, they are still filled with water, but the replaced rad (downstairs) and all upstairs rads are empty.

I'm guessing then that there is an air lock somewhere in the system preventing the water from reaching the boiler and pump?
Plan to drain down eachof the filled rads tomorrow and try to refill the system again.

 

[simond]

Turn off all the other (working) rads. Turn the pump on/off every 3 secs or so. If this fails.....

You could shove a mains hose up a drainoff. Leave the motorised valves open, and go easy.

 

[mysteryman]

You may have an anti-gravity valve for the upstairs rads on an old system with a Netaheat. This could be stuck shut. It will be on the heating flow pipe leading to the upstairs rads.

 

[NobbyD]

All fixed!

I set the main boiler valve to manual (open) and used a hose to back fill the system from the mains water supply through the drain valve.
Once the air lock was cleared, the expansion tank started to empty/fill and refilled the CH system.
All rads now bled and the CH working fine.

Thank you all for the help and advice.
Job Done!

 

[miggy]

The previous post is on about the type of system you have. There are quite a few.
If you are convinced the cold feed is clear then it sounds like a simple air lock. Various ways of curing but to involved to explain here. Involves sucking and blowing on cold feed and expansion pipes.
Basically leave it to someone who knows. End of the day gas and hot liquids, recipe for disaster.