I have a solid fuel stove, which heats my boiler through a heat exchange coil inside the boiler. Once the boiler is up to temp I can turn on the radiators and get them nice and hot. But they will cool down after a while, yet I'll still burn myself from the water that comes out of the hot tap.
The stove will die down and fluctuate in temperature as I'll forget to check it etc.
I suspect my answer to this issue is that the boiler isn't hot enough to keep the radiators hot. As once the stove cools down that heat exchange coil is effectively working in reverse, using a cooler heat source.
Basically I'm just looking for confirmation on this and maybe more detail which I may have missed.