88V8 wrote:But.... when designing a wet system if one wants different temps in different rooms, and one sizes the rads accordingly, it works, even without internal wall insulation. Provided of course that one keeps the doors shut.
V8
Yip, your right, here's an example. Our bedroom & ensuite shower room is a zone. When we waken, say 7 am, we set the temperature to 21 degrees. It takes our small 15kW gas boiler about 12 minutes to get the room up to temperature (it's only heating that room), there are two towel rails in the shower room so it gets lovely and warm quickly. After we get up we set the bedroom temperature back to 14 degrees and the temperature decays throughout the day. I generally set the bedroom temperature to 20 degrees at 10 pm, by my phone app, and the room is lovely and warm at bed time. All this could be on a timer on the local stat but we find it works better to set temperatures as required.
So, only heat the room when needed (generally for 12 minutes in the morning and evening). Save energy and have luxury of showering at 21 degrees in the shower room. What's not to like. BG said our boiler was under sized at 15 kW but it works perfectly well with zone heating and has good modulation.
I recon most gas central heating systems are grossly oversized and could be a lot more user friendly and cost effective.