Adding Radiator to one pipe system.

[MickBrown]

A customer has a one pipe heating system but no radiator in the lounge. There is a radiator in the hallway downstairs, the pipe appears from under the stairs and runs along the wall to the radiator, after the radiator it runs along the wall then up the corner of the wall to the ceiling below a bedroom above. Just before the ceiling it enters a short section of trunking which comes from the electricity consumer unit and contains a cable that feeds an electric shower in the bathroom.
The boiler is a gas back boiler, when it was last serviced they discussed with the plumber about adding a radiator in the lounge. They wanted to extend the pipe from where it goes through the ceiling in the trunking mentioned above, take it along the corner of the ceiling to the other wall, down the wall and through it at the bottom in to the lounge for the new radiator. There would of course be a return pipe to connect back in the system to keep the loop. The plumber said he couldn't extend the pipework from where they wanted but he could from under the floor of the bedroom above, take the pipe under the floor to the lounge and drop it down. They would prefer not to do this as it they would have to empty this bedroom (it is quite small) and also pull up carpets etc, to them routing it along the ceiling would cause less disruption.
Can anybody see any reason why it cannot be routed as they want?

 

[justlead1]

Hi Mick. One pipe systems work on the basis that the friction in the pipe between the flow and return branches create more resistance than the rad and pipe work from branch to rad. That is what allows the rad to heat. Ideally the one pipe needs to pass the rad as close as possible, in order to keep the branched pipe as short as possible. Although swept tees can be used they will not over come long branches. I can recall on several occasions where rads were fitted in bay windows and it was difficult to lift boards and pipes were fished say 4'-0" lengths the rads failed to get hot. Which resulted in the boards being taken up again and the 3/4" pipe between the branches being semi flattened to increase the flow through the rad and the boards replaced quick time. Not the best solution but needs must. Good Luck