Do I need a Power flush??

[prestodigitator]

Hi All my learned forum dwellers. I have an issue whereby the downstairs radiators are not getting a chance to warm up fully before the pump switches itself off, resulting in barely warm (if at all) rads downstairs. the pump switches off, as far as my laymans knowledge goes, when the thermostat on the tank tells the boiler that the water temp in it is at the set temp (actually the pump turns off about 1 minute AFTER the boiler turns off, but I think this is a safety feature on the pump ,no?).
My question then, Is there a way to over-ride whatever is telling the pump to turn off so that the radiators get a chance to heat up, or is the reason the pump is going off because the return temp of the heating water is being read as warm due to some blockage somewhere?
Secondly, isn't the manual room thermostat I have in my front room supposed to make sure the heating stays on if i set it to, say, 18 until the room reaches that temperature? at the moment i cant seem to make the dial thermostat do anything. It CLICKS on and off when i turn the dial at what i assume is the actual temp of the room at that time but this does not make any difference to the boiler at all (asside from blowing the 3A fuse when i had the blue and the yellow wires the wrong way round! oops..).
Im pulling my hair out and thinking there MUST be a blockage somewhere but any advice gratefully received.
thanks,
-Presto.

 

[D_Hailsham]

Please post full details about your system.

- Make and model of boiler

- Make and model of timer(s)

- Make and model of thermostat(s)

- Make and model of motorized valve(s)

- Make and model of HW cylinder (if known)