Hi All I have an issue where the last two radiators (furthest from the boiler) are not heating. I have taken a few boiler engineers/plumbers to have a look but they are not able to fix the issue. So let me give a bit of a background. This should answer a few questions that you are likely to ask. This heating is on a fourth floor flat. The central heating system was installed by the council around 1994 and there has never been any issues with any of the radiators. The boiler (with a hot water tank) was installed in the bathroom which is kind of central to the property. Around 2010 the boiler packed up and we replaced the boiler with a combi boiler. A few years after this we started getting issues with the last two radiators not heating up. I was insured with British Gas and they used to come and do their stuff and get the radiators to work. They kept on insisting that a power flush was required. I didn't give them the go ahead as it was very expensive. Eventually in 2016 I got a power flush done by a powerflush company. They used heat guns to check that the water was flowing and that there was no blockages. This was certified and all was well. Around mid 2017 the boiler packed in and it was not repairable so I got the boiler replaced. At this point I had the boiler moved to the kitchen which is at one end of the property as the bathroom is apparently no longer a place where you should have a boiler. Since installing the new boiler we do not seem to be getting any heat going to the radiators in the end two rooms. We have tried re-balancing all of the radiators and we get them to work. However, once the heating is switched off and then switched back on again those two radiators stop working again. I have spoken to a few people regarding this and they are a bit baffled as to why this is happening. The radiators have been re-balanced and a powerflush was done only recently. The boiler is pretty much brand new. When we close off a couple of radiators close to the boiler it seems to get the radiators going in the end rooms but we can't be doing that all the time. Any advice would be greatly appreciated. The property is in central London if anyone thinks they know what the issue might be and wants to come down and have a look.