My central heating system is over 40 years old. A mixture of 15 and 22mm pipework to and from the boiler (which is 15 years old), while the rads are served via microbore pipe from the two distribution trees hidden away under the back bedroom floor.
A few weeks ago, the pipework became blocked and fortunately a local plumber managed to clear it. He gave me some instruction to clean the system, which I've followed closely:
1 - Refill the system with plain water, run for a day, then drain - done
2 - Refill the system with plain water again, run for a day, then drain - done
3 - Refill with water, plus Sentinel X400, run for two/three weeks, then drain and refill plus Sentinel X100.
I wasn't happy with the state of the water that I finally drained after step 3, so I refilled with X400 again, and that's been running for a week now.
One thing that I've noticed is that when the system runs for hot water and heating, it runs quietly, but when it is switched to hot water only, there's a lot of noise from entrained air, and I'm trying to understand why this is. All the rads are getting hot - no cold spots at all. The entrained air gathers in the towel rail, which is the usual place where air eventually gathers.
My guess is that with hot water only, there's still a sufficient partial blockage of the pipework some where and that air is being dragged down the vent pipe. Whatever it is, the X400 isn't clearing it.
I'd appreciate any thoughts on the noise issue and whether a dose of X800 might be better at clearing the system, or do I need to break into the pipework and clear it the old fashioned way?
Thanks
Chris
A few weeks ago, the pipework became blocked and fortunately a local plumber managed to clear it. He gave me some instruction to clean the system, which I've followed closely:
1 - Refill the system with plain water, run for a day, then drain - done
2 - Refill the system with plain water again, run for a day, then drain - done
3 - Refill with water, plus Sentinel X400, run for two/three weeks, then drain and refill plus Sentinel X100.
I wasn't happy with the state of the water that I finally drained after step 3, so I refilled with X400 again, and that's been running for a week now.
One thing that I've noticed is that when the system runs for hot water and heating, it runs quietly, but when it is switched to hot water only, there's a lot of noise from entrained air, and I'm trying to understand why this is. All the rads are getting hot - no cold spots at all. The entrained air gathers in the towel rail, which is the usual place where air eventually gathers.
My guess is that with hot water only, there's still a sufficient partial blockage of the pipework some where and that air is being dragged down the vent pipe. Whatever it is, the X400 isn't clearing it.
I'd appreciate any thoughts on the noise issue and whether a dose of X800 might be better at clearing the system, or do I need to break into the pipework and clear it the old fashioned way?
Thanks
Chris
