TS Valve TS5301 Automatic Air Vent 1/2 inch – Vaillant, Riello, Biasi Compatible (4038032, BI1002111)

TS5301 is an automatic air vent that releases air accumulated in the boiler and heating circuit. It has an all-brass body; there is a knurled cap and a brass outlet nipple on top, and it is mounted from below with a 1/2 inch male thread connection. Thanks to the float mechanism, air is released automatically under system pressure.

It is listed in manufacturer catalogs under codes 4038032 and Biasi BI1002111; it is used in Vaillant, Riello and Biasi boilers.

What Does the Air Vent Do?

• Air entering the circuit causes the upper part of radiators to stay cold and the circulation pump to make noise.
• In a heat exchanger with an air pocket, heat transfer drops and the boiler runs unnecessarily.
• When the air vent is clogged or its float is stuck, air cannot be released; in this case the part is replaced.
• Water leaking from the body indicates that the seal or float seat has failed.

Technical Specifications and Installation

• Type: Automatic air vent (float type)
• Connection: 1/2 inch male thread
• Body: Brass (including cap)
• Corresponding Codes: 4038032 · Biasi BI1002111
• Location: Air release in Vaillant, Riello and Biasi boilers

Installation Notes

• The air vent is always mounted upright; if fitted horizontally, the float will not work.
• Before installation, the system pressure is reduced and the circuit is drained.
• Suitable thread sealing (PTFE tape or a self-sealing fitting) is used, and the body is not overtightened.
• The cap on top is left one turn loose so that air can be released during operation.