How to identify what type of system I have?

[Jdbecks]

I replaced a radiator from a single to a double and now the radiator lock shield is leaking from the spindle. The lock shield is quite old with a 3/4 union. I looked to see if I can pack the spindle but the spindle is threaded inside a threaded nut, which when I undo, also unscrews the lock shield spindle.

I have a condensing boiler with a vented hot water tank, in my loft I have an overflow/expansion tank which supplies the cold fill loop for the boiler. I was under the impression the cold water tank in the loft was an expansion tank for the central heating, but then why does the boiler require a cold fill loop and pressurised to run?

Its so I can drain the system and replace the lock shield, but I might pay a plumber to do it and also replace another radiator just in case I encounter any issues.

In my previous house my central heating had a cold expansion tank in my loft and a second tank too. So this house only having one throws me.


Thanks.

 

[ShaunCorbs]

Sounds like the tank in the loft is for your hot water eg cylinder (should be a big ish tank around 30-50 gallons)

The heating sounds sealed eg filled via the filling loop

 

[Jdbecks]

Thanks, it’s late and and I just read my op! it’s a little mumble jumble so apologises for that.

If my system is sealed, that means I can just drain my central heating and I won’t have to isolate anything else as the only feed is via the fill loop for the boiler?

 

[Deleted member 32524]

Correct. If there is a pressure gauge and a filling loop just open drain point/s and open bleed valves on rads. Then close them and fill and then bleed again, top up to 1 bar when cold. Add enough inhibitor