Hi... got a new rad fitted during garage conversion. It takes ages to heat up while all the other rads heat up very quickly. The new rad will heat up eventually but it takes approx. an hr to get there. Heat does get to the inlet pipe pretty quickly just before it enters the rad but the outlet pipe on other side of rad will remain cold until the rad heats up. There was a smaller rad previously there which had no issues heating up. The plumber extended the inlet/ outlet pipes to fit to the new rad which is bigger than the old one and required extending the pipes approx. another 5metres. They did try to balance the rads but didn't make a difference and has been bled also, again with no improvement. Noticed the pipes used to extend are smaller than existing pipe size but nothing major.... 15mm and 10mm. Wondering if extendiing these pipes by 5mtres would impact the water flow to the extent it is struggling to get thru' the rad and if it would have been better to tap into the existing CH pipework closer to the new rad....Any ideas folks ? My system is a gravity fed with an expansion tank...
