T-Piece

A galvanised steel T-piece splits a duct into two at a right angle, or merges two ducts into one. Available from 100 to 250 mm.

A T does not give each branch half

That assumption is what makes most splits fail. Air takes the path of least resistance, so the short branch with few bends structurally gets more than the long one. On a T-piece the side branch also leaves at a right angle while the straight-through branch does not, which favours the straight path from the start.

In practice that means two things. Make the two branches as equal as you can in length and number of bends, and expect to throttle: a damper, or an opening partly taped over on the branch getting too much, until the split is right.

And do not count your capacity per branch. One 400 m³/h fan serving two rooms is 400 in total, not 400 twice.

Available sizes

Technical Specifications:

• Fitting type: T-piece, three connections
• Angle: side branch at a right angle, 90 degrees
• Build: galvanised steel
• Connection ends: all three suit ducting and rigid parts

Frequently asked questions

Can I merge with it rather than split?
Yes. Bringing two extractions onto one fan uses the same piece, provided that fan can handle the total.

Are all three connections the same size?
Yes, this piece is equal sided. To step down to a smaller branch, put a reducer after it.

When would I take a Y-piece instead?
As soon as capacity is tight. A 45 degree split costs noticeably less pressure than a right-angled branch.