stoky house

Hello I'm new to Buildhub. I am a home owner. I live in a small 3-storey house with underfloor heating (no rads at all). The UFH doesn't work too well. Could this be anything to do with there being only 1 manifold (on the middle floor)? If so, what are my options? I don't think it will be viable to change the design....would it be possible to introduce an annual air-bubble removal process? How would that work? Any advice you can offer will be most gratefully received.