Flexi connector pipes or not

[mk1_man]

Hi all,  1/2 way through my self install of Vaillant heat pump and cylinder.  I am making an effort to give the flow the best chance it can by using sweeping bends, 28mm pipe for all main runs, 1 1/4" esbe diverter valve etc.  I have looked at the 28mm flexible connector pipes and I have to say not overly impressed with the internal diameter, appreciate its only a 750mm run but its a chunk smaller than 28mm copper pipe.  My heat pump is 300mm away from utility cavity wall so pipe run is really short, basically straight out of the back and through wall via pair of anti freeze valves.  I have read a few comments about not requiring flexi hoses on the Vaillants.  What are peoples thoughts?

[crispy_wafer]

Was of the understanding the flexi hoses are for vibration damping, and the softening transmission of the fan noise through the rigid copper.  I could be completely wrong though.  🤔

[sharpener]

Have just had their 12kW installed, with the flexis. The internal pump is v powerful, it will push just under 2000 litres/hr through the HW coil on its own, even though the pipework to it is only 15mm (am amazed this is not noisy).

 

So I would not worry about the i/d of the flexis. As @crispy_wafer says they are there to provide mechanical decoupling and not undo the good work of the compliant feet. The end result is very quiet.

 

Good luck with yr DiY installation. I had four men here for four days, watching them it seemed fairly straightforward except for connecting to the myvaillant phone app which the lead installer did for me this morning.

 

Are Vaillant going to give you an extended warranty though?