I am having a couple of problems with my radiators.
The first is that when I have the boiler set to hot water only, the rads come on too.
The second and most frustrating, is the time it takes for the radiators to actually heat up.
On a good day it can take 1 1/2 hours.
When I say heat up, I mean fully. However it can take an hour just to get any heat in them.
I've tried turning the downstairs rads off and just having the upstairs on first. Switching them all off and putting them back on one at a time. I've bled them too, but none of these solve the problem.
Hope someone can shed some light on it.
There could be several things causing the problem you describe but as you have not described your system in any detail, it is very difficult to offer any useful advice!
Is the boiler big enough for the number of radiators and firing correctly? Is the pump running fast enough (assuming you have a pump)? Is a bypass too far open? Is water bypassing the heating circuit around a tank coil? What zone valves do you have (if any)?
The more information you give the more useful the replies.