Heat Recovery Wheel Seal Brushes: Where They Go, What to Measure and When to Replace

Where the seals sit

• Perimeter (circumferential) seal: runs around the rim of the wheel, closing the gap between the rotor and the casing so air doesn't bypass the wheel.
• Centre (partition) seal: runs across the face of the wheel along the divider between the supply and exhaust sides, limiting leakage from one airstream to the other.
• Both are usually fixed to the casing or partition, with the bristles brushing against the rotating wheel.

Why brush seals

Large wheels have some run-out and wobble, and they expand and contract with temperature. A brush seal flexes to follow that movement while staying in contact, and the soft fill doesn't scratch the wheel. As the bristles wear, the seal keeps working until the gap opens up enough to need replacement.

Materials and construction

A typical seal is a flexible strip: a PVC or similar base that mounts to the frame, with dense synthetic bristles. Some designs add a thin plastic fin through the centre of the bristles, which blocks air passing straight through the pile and improves sealing. Bristles with UV-resistant and anti-ageing additives hold their shape longer in units exposed to daylight or temperature cycling.

Our rotary heat exchanger wheel seal brush is this construction: BCF yarn bristles with UV-resistant, anti-ageing additives on a PVC base with a centre plastic fin, an added sealing film and reinforced adhesive, supplied in rolls.

What to measure for a replacement

• The gap to be sealed with the wheel at rest, measured at several points around the rim — choose a bristle height that covers the widest reading with some contact.
• The base width and how it is fixed: adhesive, clipped into a profile, or screwed through a holder.
• The total length needed: the wheel circumference for the perimeter seal, plus the partition length for centre seals (on both faces if the unit has seals on both sides).
• Temperature and humidity of both airstreams, and whether the unit is indoors or exposed to daylight.
• A photo of the existing seal in place, ideally with a ruler across it.

Signs the seal needs replacing

• Visible gaps between the bristles and the wheel, or bristles bent flat and no longer touching.
• Increased leakage or carry-over between airstreams, or a fall in recovery efficiency that isn't explained by dirt on the wheel.
• Bristles that are brittle, matted with dust or partly detached from the base.

Frequently asked questions

What is the difference between a perimeter seal and a centre seal?

The perimeter seal closes the gap around the rim so air doesn't bypass the wheel; the centre seal runs along the partition across the wheel face to limit leakage between the supply and exhaust airstreams.

Why use a brush seal instead of a rubber seal on a heat wheel?

A brush seal follows the wheel's run-out and thermal movement while staying in contact, and it doesn't scratch the wheel. A rigid seal either loses contact or adds friction when the wheel moves.

What does the fin in the middle of the seal do?

The thin fin through the bristles blocks air that would otherwise pass straight through the pile, improving the seal while the bristles keep contact with the wheel.

How do I order the right size?

Send the gap you need to seal, the base width and fixing method, the total length and a photo of the existing seal. We supply seals in rolls and confirm the size before production.

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