Can I add 10mm pipe to 8 mm pipe

[hoopyman]

My radiator at the back of the house had 8 mm pipe I connected 10mm pipes to these using olive connectors and teed off the flow and return moving it along the wall then reattached a new rad with new valves and also add another small radiator 3 foot the other way hence the tee both rads aren't heating up I've tried:

Bleeding (buckets out)
Turning all other rads off to move any blocks.

Is it the pipe being 10 mm rater than 8????

The pipe I laid behind the wall isn't totaly horizontal could it be that and there is a 90 degree turn in the pipe ....

Pleas help

 

[Dukie1977]

Any chance of somekind of diagram as to what you've done?

 

[chr15]

Were all your radiators getting hot prior to fitting the new rad?-and did you completely drain down the systen. What type of boiler have you got?