Draining Central Heating with Underfloor heating

[Chris1312]

Hi
My CH system is a Rayburn Heatranger with underfloor heating downstairs and conventional radiators upstairs.
I need to drain the upstairs system.
My questions is.
Are the 2 systems separate or connected ?, ie if I drain the upstairs system with the pressure drop in the underfloor heating system.

Rgds Chris

 

[Deleted member 267285]

If you’re only draining upstairs the underfloor should remain unaffected, the same way as if it were radiators. Water will stay in the ufh circuit because that’s the lowest point.

 

[muggles]

But they are connected and the pressure will drop