View on Low Loss Header for domestic property

[Zencap]

We are experiencing problems with our heating system which has become apparent after adding a single zone UFH to a large kitchen area.

When the UFH kicks in, the flow to the CH Rads cools off. When the UFH is not on the Rads (13 in total) all get hot (quite slowly downstairs.

UFH has own pump and CH pump is brand new 15/60 and made no difference. System was powerlfushed in last year and boiler is under a year old Viesmann-100w 26kw. When UFH was done, new piping was done to all 4 downstairs rads.

2 plumbers are stumped by the issue as set up should work. Proposals are

Change Flow and Return pipes (which are hidden in walls) from boiler to air cupboard to 28mm.

Install Low Loss Header - a destratification pump to a low loss header (LLH). Before the LLH run a 22mm f & r to the dhw cylinder. Downstream of the LLH install a primary pump to run the CH circuit and UFH.

Pressurise the system

what are peoples views on this - any other ideas?

concern on LLH is this over kill and cause issues long term?

pressurising system is risky given upstairs pipes are older and could cause issue.

help greatly received

thanks

 

[John.g]

KOP, have you ever noted the flow/return deltaT on any gas boiler(s) while runnng on UFH only?.

 

[king of pipes]

No mate but I can measure it if you want ?? I have several I look after and service each year with a mix of ufh and rads . Cheers kop

 

[John.g]

Yes, do please sometime, on UFH only.

 

[ShaunCorbs]

I’m guessing a delta around 7-10 on start up and around 2-5 once warm