Old Single Pipe heating system problem

[Graham SW]

I have recently had to cap 3 radiators in a single pipe system and since then the system has stopped working. The boiler works and the pump seems to turn on but water doesnt seem to circulate. I thought maybe capping the radiators had broken the system loop but dont think this is the case anymore. Anyother ideas? This is only temporary while other work is being done before a change the system but some heat would be nice right now

 

[Last Plumber]

I have recently had to cap 3 radiators in a single pipe system and since then the system has stopped working. The boiler works and the pump seems to turn on but water doesnt seem to circulate. I thought maybe capping the radiators had broken the system loop but dont think this is the case anymore. Anyother ideas? This is only temporary while other work is being done before a change the system but some heat would be nice right now

Capping rads won't stop the system working. Maybe it is air locked?

 

[Best]

It shouldn’t stop working unless the one pipe system was literally routed through each radiator to the next.
Or you have an airlock caused when you drained system?

 

[SimonG]

Check the header tank. The other rads full?

 

[Graham SW]

Check the header tank. The other rads full?

There's 1 radiator I can't get the drain/vent to open so its probably full of air any ideas how to get rid of the air if a can't open the valve?
Thanks

 

[SimonG]

Drill and retap a new one.

Shouldn't stop it running.

Get hose onto drain off and back fill with mains cold. Just don't go crazy and make sure overflow on header tank all secure to outside.

 

[SimonG]

Bled the pump?

 

[Graham SW]

Drill and retap a new one.

Shouldn't stop it running.

Get hose onto drain off and back fill with mains cold. Just don't go crazy and make sure overflow on header tank all secure to outside.

Thanks I'll give it go tomorrow

 

[townfanjon]

Thanks I'll give it go tomorrow

Did you drain the full system?

 

[Graham SW]

Did you drain the full system?

Yes

 

[townfanjon]

Yes

Erm , possible blockage on your feed and vent where it joins the system

 

[Graham SW]

Erm , possible blockage on your feed and vent where it joins the system

Its really strange the pipe going into the pump gets hot but the output pipe does not but the pump seems to be working as I can feel it when it turns on

 

[Stigster]

The motor on the pump may be spinning but the spindle may not be turning the impeller giving the illusion of a working pump. As has already been suggested it may be air in the pump too. You can usually take out the slotted screw on the front of the pump to bleed air. On some pumps, older ones usually, you can also see the impeller under that bleed screw. Again, most impellers will have a slotted screw in the centre, with the system calling for heat you can give this impeller screw a quick twist with a screwdriver to get it going again if stuck. A small quantity of water will escape but nothing that couldn't be handled by a bucket or other container to catch the water.

If this works it might get your heating going again but the pump would want replacing sooner rather than later.