DIY Doctor UK DIY Forums

Hi
We have had a loft extension done and heating doesn't work.
We asked our plumber to have a look at it. He says the boiler (eco tech plus 831) on ground floor is fine to heat the loft for the number of radiators we have and the reason the heating is not working is because the pipes in the loft are 15mm and they need to be 22mm to get the water moving up there. He also said that there were too many bends in the pipes at the moment which were not helping.
The original plumber is not sure that is the reason but he doesn't know why the heating wouldn't work.
Any advise would be appreciated. Thanks

Is it a sealed system or vented as in is there red expansion vessels on your heating or is there a small 4 gallon tank in the loft?

dont know but no tank in loft. its a combi

have you tried turning the radiators off in the house at the rad valves to see if radiators get hot in loft?

Possible air lock

or your whole house could possibly need radiator balancing

they did work when two of the radiators on the first floor were off but not anymore when they are off. (after they switched them back on none of the radiators on top two floors worked but now middle floor work again but not top floor).
where would the airlock be - we have bled all the radiators. do you think bigger pipes would help?
thanks

watch this

https://www.youtube.com/watch?v=U0O-EAEtXJQ

I recommend turning them all half turn and if some are only warm and not hot give another quarter turn obviously the rads furthest from the pump will be open more than the ones closer

two plumbers have tried to do that and balance the system and its not helped. so he said its because the pipes upstairs are too narrow and need replacing with bigger ones...