3 storey building CH burner upstairs lowest radiator does not work - WHY?

[Dusan]

It is brand new installation, CH burner on the 2nd floor, 6 radiators on the 2nd floor, 6 radiators on the 1st floor > everything worked more than fine. CH burner is of very high capacity and can provide heating to 20 such radiators.

Then I just wanted one additional radiator on the ground floor.

Feed to radiators goes like this: just 2 pipes from the burner; on 2nd and on 1st floor there are 2 main pipes 22mm going in te middle of the foor, in the middle of the width of the house. Radiators are conected with 16 mm pipes from those main pipes.

Two 22 mm (first it was tried with 16 mm) pipes go from 22 mm main pipes on the 1st floor down to the ground floor radiator (5m length). That radiator never wanted to work unless the flow is almost completely interrupted on all other radiators (by screwing valves on the bottom entry interface at each radiator, then it works but everything else does not i.e. CV burner has to work at its maximum etc..

Plumbers tried everything, inlcuding replacement of the radiator, trying all combinatios of connections (the radiator can be connected in the midle or on its sides), they even exchanged cold water entry with warm water, etc. System was filled in from that lowest radiator up, there is absolutely no air in those two pipes that bring water to the radiator (they say).

Then they said this lowest radiator is too big (compared with radiators on the 1st floor, it is indeed the biggest, almost 2x more power than those which are upstairs (it is 100cm x 90 cm high, with 2 convectors).

If the water is released from this radiator, it becomes hot immediately, in seconds. So, there is a problem with the flow.

Can this radiator work? Why is it not working in the system that otherwise works perfect? it is 3,5 m below radiators on th 1st floor, and all plumbers here say it does not matter, it can work. But then they cannot make it work unless destroying the good settings upstairs.

 

[Mike Jackson]

You're going to need to get some valves fitted on the heating circuits and balance the circuits rather than the individual radiators. I had a similar problem some years ago. Two radiators on a separate circuit wouldn't work unless I balance the rest of the radiators down so far they were barely working. By balancing the circuits I could leave the lockshield valves on the rest of the radiators far enough open that they still worked when the other two radiators worked.

 

[Dusan]

The problem is there is no way I can access the pipes in the floor any more, plus there are no real circuits, just two parallel situations (1st and 2nd floor horizontal cold and war water leads and radiators connected at their ends), connected to a single vertical lead from CV heater, and the problematic radiator connected on the 1st floor main water leads as well.

Does it make sense to modify the diameter of the valves on that problematic radiator i.e. remove them, or when they are opened fully that's the same?

 

[Dusan]

Also, does the position of this radiator has any influence on its work i.e. would it be the same if it would be at the 1st floor and not on the ground floor (local CH "experts" /under quotations as they did not make it work/ say it has nothing to do with the height location??

Is there ANY sense in reversing the warm and cold water leads, so that warm water really enters the radiator at the lowest point, and cold pipe is connected diagonally at the top of the radiator? One of them did that, it worked with problem work of everything else and CH burner overloaded i.e. producing much warmer water than when it just powered 1st an 2nd floor radiators.

There is no separate pump outside the burner, should installation of one help (but I would like to avoid that as the burner is very sophisticated and should be self sufficient for this configuration)?