i recently had a new condensing boiler and water cylinder replaced the existing radiators all have thermostatic valves fitted to them and worked fine until the boiler was replaced now all of my radiators when turned on, get as hot as the radiator without the valve on, i put each valve on number 2 which should be slightly warm, instead they are very very hot to the point you cant hold your hand on them for long one of the bedroom radiators can be heard bubbling like a kettle, i find it hard to believe all the valves could suddenly develop a fault could there be another reason for this ie fault with the fitting of pipework i am really concerned as we have young children in the house any thoughts on this much would be much appreciated
John what are you on about. Thermostatic radiator valves DO NOT control the temperature of the water in a radiator,that is set on the boiler.They take the air temperature surrounding the valve and control the room temperature by reducing or increasing as required the flow of water through the radiator.
I think you might be confusing a thermostatic mixing valve with a thermostatic on/off valve. The thermostatic valves on radiators are on/off valves. They don't control the temperature of the water, they just shut the radiators on or off when the room temperature goes below or above a certain point. The radiators with thermostatic valves *should* get as hot as the radiators without (at least until the room heats up). I'm guessing your new boiler is set to heat the water to a higher temperature than the old boiler.
Actually, the thermostatic valves do control the temperature of the water in the radiator. I suspect the new boiler is storing water much hotter than the old one, because of the threat of legionella breeding there. A thermostatic mixing valve may have been installed at the point the water leaves the boiler, to introduce cold water as it heads out to the radiators, hoping to make the water closer in temperature to what you actually want in the radiator for heat. If they have the mixer adjusted too hot you can adjust that to have the water leave the mixer cooler than it is now. If there is no mixer in your new installation, then you would need to reduce the setting on your individual radiators to adapt to the hotter water they are using in boilers now, due to legionaire's disease.
