On 2011-06-06, harry wrote:

discussion about single pipe system and full-flow TRVs edited out

The pressure drop across the rad depends on the type of tees. There
are plain tees, swept tees and cup tees in ascending order of
preference.

The Americans use Monoflow tees for single pipe systems, see:

www.heatinghelp.com/article/17/Hot-Water/74/Diverter-Tee-Hot-Water-Heating

I have never seen Monoflow tees for sale in the UK, but have come across
proposals to fabricate a venturi tee out of a tee and reducer, such as:

www.torrens.org.uk/HowTo/Injector/index.html

Anyone tried this to soup up an older UK single pipe system?

MJA