Central Heating - cant achieve the correct temperature.

[jbs29uk]

hi - just had a new Valiant condenser boiler and new radiators fitted, replacing an ageing system. Problem is, I cant get the upstairs radiators nice and hot. They are cool upstairs but hot downstairs. So, I turn up the boiler to max - 70c or 75 (which ive since been told I shouldnt do) - lovely and hot upstairs - and turn down the TRVs on the radiators downstairs. But, if I turn the valve to be greater than 3, the radiator is boiling hot. Turn it below 3, the raditator turns off. Seems to be more of an on/off switch. The temperature dial tn the hallway doesnt regulate either - it seems to turn the whole system off or on when it "clicks" but thats it. Plumber difficult to contact. Any advice very much appreciated!!!!

 

[compheat]

No disrespect but you obviously don,t know how the controls work

(1) the boiler stat controls the water temp going through your radiators so on low means warm and High means hot.
(2) the room stat sensenses the air temp around it, so if its clicking off at 20 then its reached the required temp, if this isn't hot enough for you tun it up.
(3) the TRV's also sense the air temp so if its going off on 3 which is 20 deg C then again its up to temp, if 3 isn't hot enough turn to no 4 or 5.

 

[matt1e]

to add to Compheats post
you need to ignore how hot or cold the rads are, they are just there to add heat as necessary.
hows the room temp?

 

[jbs29uk]

Thanks both - you're right, I didnt understand how the system worked.
I turned the boiler upto 70c, turned the thermostat to 20c and left the downstairs radiator TRVs on 3, the upstairs on 5 and it works OK. The radiators do cool / heat as required to maintain teh room temperature. My concerns are that the boiler seems to be on all the time pumping out really hot water just to ensure that the upstairs radiators are hot but I guess I'll have to live with that. Some forums say this is OK, some say that condensing boilers work best around 2/3's max. But, thanks again.