Spotlight on: swimming pool ventilation with Martin Killen of Recotherm

elemental speaks to Martin Killen, Founder & CEO at Recotherm, about the challenges of keeping swimming pools efficiently ventilated.

Q: For those new to Recotherm – what’s the backstory?

Recotherm was founded to create energy-efficient swimming pool ventilation units. We started building refrigerant dehumidifiers but quickly realised that the minimum fresh air requirement was doing most of the dehumidification, so we decided to design a better fresh air unit. Back in 1985, most pool halls were relying on dehumidifiers that recycled warm, moist air. It worked, but the air quality was poor and the running costs high. We noticed on several sites that when outside air was dry enough, it could do the dehumidification naturally – so we designed a system around that principle.

By the early 1990s, we’d moved away from traditional dehumidifiers and developed controlled fresh-air systems that constantly adjust how much outside air they bring in. It was a turning point for pool ventilation – cleaner, fresher air for bathers, less corrosion in the building, and lower energy use. That same idea still underpins everything we make today.

Q: How would you sum up the range today – any standout unit?

Everything we build follows the same principles of precise fresh-air control, high-efficiency heat recovery and control strategies that constantly tune airflow and fan speed. A unit we’re especially proud of is Aerum. Instead of taking heat from a boiler, it draws heat directly from an air-source heat pump through a refrigerant coil in the unit – no hot-water circuit. It’s ideal where fossil fuels are restricted or for low-carbon new builds.

Q: Why are pool halls such a demanding environment?

Corrosion and condensation. If chloramines build up in the air, they attack metalwork – even stainless suspension wires. Without the right ventilation you’ll see misted glazing, mould and long-term fabric risk. Pools aren’t just another AHU application; you must manage evaporation, temperature and humidity together.

Q: How do your systems differ from generic HVAC or imported pool units?

Hardware helps, but the real edge is controls. Our strategy – refined over four decades of pool-only work – continuously balances fresh air, recirculation and heat recovery based on what the pool is actually doing. That avoids classic pitfalls like dampers fighting each other or coils starved of airflow. Some competitors copied the move from dehumidifiers to controlled fresh air; they didn’t inherit the years of control logic.

Q: Where’s the next wave of innovation?

Filtration. We think it’s under-spec’d, especially on domestic pools in polluted areas. Better filters cost a little more but improve air quality and protect plant. Beyond that, we focus on marginal gains – a slightly more efficient fan here, a smarter recovery tweak there. Tiny improvements add up over a unit’s life.

Q: What does the business look like today?

We’re 19 people and growing. Our service department now supports both Recotherm sites and third-party pools nationwide. Everything is designed, built and supported in the UK, and around 80% of parts are UK-sourced – good for sustainability and for keeping projects moving when supply chains get sticky.

Q: Who should seek you out at elementalLONDON?

Two main groups. First, M&E consultants who want confidence on pools, especially non-standard briefs where a simple guide can come up short. Second, operators and developers who want UK-built systems with responsive support. Pool contractors tend to have their own trade show, but they’re very welcome to drop by.

Q: Do you provide training or guidance for specifiers?

Yes. We run CPD sessions that go beyond rule-of-thumb air volumes to evaporation calculations and practical control strategy. We’ll deliver a shortened CPD at elemental – a clear walkthrough of how controlled fresh air keeps chloramines down, protects the building and makes the space feel better to breathe.

Q: Final message for visitors choosing a pool ventilation route?

You don’t have to import to get best-in-class. With UK manufacture, UK parts and UK service – plus four decades focused solely on pools – we’ll help you design a solution that protects the fabric, keeps operators happy and lowers lifetime cost. Come say hello at elementalLondon, put the controls to the test and tell us what you need on your next pool.

Come meet the Recotherm team at elementalLONDON, 19-20 November at Excel London. Register for your free ticket here.