hi, we have a problem with one rad not heating (last couple of months) and boiler losing pressure (only discovered this over the weekend). We repressurised to 1.5 bar yesterday and it went down to 0.5 overnight. We refilled again and will check if this has changed in the morning. The questions I have are: 1) what would cause a rad (probably last in the circuit) to only heat when all others are shut off? It’s the only one with a fully open lockshield. It has been bled, as have the others. 2) other than a leak, what would cause the boiler (installed 5 months ago) to lose pressure from 1.5bar to 0.5 overnight? 3) could the fact that we have recently (1 week ago) changed from only heating on demand to thermostat controlled heating (set to 19 degrees) have something to do with the pressure issue? Thank you!