More visits to the hardware store for today's episode of Fun With Pipes.
The job should have been simple - drain the heating system so I can take radiators off the walls, and pull down the walls behind the radiators. And the first part was - turning valves on and off to drain the system. Then came the part where it got tricky - opening the bleed valve on a radiator to let air in, and thereby let water out. What I thought was a radiator bleed key turned out not to fit the radiators (despite being among general tools it turned out to be a key for one of the old clocks that was in a totally different part of the house). So off to the hardware store to buy a key, except they didn't have anything that fit. So in the end I tried using a variety of sockets and still nothing fit, so I used a pair of pliers to open a valve. And then the water started to drain out, and continued to drain for nearly two hours.
Finally it was done, so I could flip more valves to open and close different sections and refill the system so I could turn the hot water back on. And then I found one valve leaking a little (I suspected it was faulty, and now I'm pretty sure it is), and for good measure the drain valve also had a slow leak. So back to the hardware store to get a cap to put on the drain pipe, until I can get the valve replaced. Rather annoyingly, that means draining the system again but at least this time the heating loops can be isolated so they don't drain. I just hope I can physically get at it - everything looks like it has been designed to be as inaccessible as possible. I may end up putting an angled extender on it, just so I can connect more useful valves to it.
Now it's in a state where the main water feed into the furnace is turned off because the pressure regulator needs replacing and if I leave the main water feed open it builds up too much pressure, which then releases hot water through the overflow. At the same time the drain valve is still very slowly leaking despite the cap, and of course there's no feed active to replace it. So I need to check the pressure in the furnace every couple of days to make sure it hasn't dropped too low, and topping it up if it has. In a couple of months we're having the thing serviced, and that seems like a good time to get the heating guy to replace some of the more esoteric parts.