What is an Injector Tee/Venturi ??

[Marty32]

Good afternoon

Could someone explain to what an injector/venturi tee is on a central heating system is and where and why you would use one?

Many thanks

 

[ecowarm]

Have a look here

 

[chris watkins]

oo very old, injector tees were used where a boiler had only a common return tapping & the system was gravity hot water primarys with pump heating. It was installed were the two joined on the return back to the boiler to stop the higher pumped heating from pushing back up & stopping the gravity HW circulation.

 

[ecowarm]

Still in use on solid fuel boilers.

 

[Marty32]

oo very old, injector tees were used where a boiler had only a common return tapping & the system was gravity hot water primarys with pump heating. It was installed were the two joined on the return back to the boiler to stop the higher pumped heating from pushing back up & stopping the gravity HW circulation.

Ok I think I get it - but if I just added a normal end feed soldered tee fitting i.e 22 x 22 x 22mm it wouldn't work?

In normal circumstances i.e a fully pumped system, it wouldn't need an injector tee just connect into the return to the boiler at any point for example return from heating circuit could connect into the return pipe 2 meters away from the boiler and the primary return connects at say a metre from the boiler etc?

Thanks again

 

[chris watkins]

Hi
No it may not work as you described as the pumped heating return may block the gravity water entering the same pipe. You can make your own injector tee by using an internal 22x15mm e/f reducer but put it inside the end of the 22mm equal tee, you may need to extend it using a sort piece of 15mm so it goes passed the centre tee from the gravity return (see pic's from web site link on ecowarm thread, for idea). Not done it myself but from memory I think it can be done & it works.

 

[AWheating]

the tee would be 28mm normally as primary gravity pipework is normally 28mm and you could make one using a reducer as chris suggested. I think you would be looking to pay £15 upwards for a proper tee. Personally i would get a proper one and save any headaches you may get. Not much difference in price really after you have brought a 28mm end feed tee and reducer.

 

[Marty32]

Thanks all for the very useful info!

 

[stevetheplumber]

you can do it use an internal reducer cut the large end short and put it in tee backwards so it leaves room for the pipe to fit behind it best to braze or silver solder it in and then soft solder it into position using a coupling