Overview
Three developments in the first two weeks of September 2026 will shape HVAC specifications well beyond this quarter: liquid cooling has crossed from pilot projects into volume delivery, propane (R290) heat pumps kept expanding at IFA 2026 in Berlin, and a cooling-tower-linked legionella outbreak in Spain put water-side hygiene back on the agenda. A fourth, quieter signal came from the United Kingdom, where retrofit heat pump installations fell 22% in the first half of the year — evidence that the retrofit market now rewards control upgrades rather than full equipment replacement.
For anyone specifying valves, actuators, sensors or thermostats, the common thread is the same: the control layer is where each of these industry shifts is actually resolved.
Key Points
- Liquid cooling is now a delivery problem, not a concept. AI rack densities of 80–120 kW have taken air cooling past its practical ceiling of 15–20 kW per rack, and vendor roadmaps are fully liquid-cooled.
- R290 keeps taking share in European heating. A3 refrigerants move safety logic — and therefore leak detection, interlocked valves and accurate sensing — into the controller.
- Water-side hygiene is back in the headlines after an outbreak in Spain linked to cooling towers. Temperature control, isolation and trend logging are the practical levers.
- Retrofit demand is control-led. With UK retrofit heat pump installs down 22% year on year in H1 2026, the growth is in upgrading the control layer of plant that already exists.
1. Liquid Cooling Moves From Pilot to Volume Delivery
The number that matters is rack power. Mainstream AI server cabinets now run at 80–120 kW, with high-density clusters peaking around 140 kW, while conventional air cooling has a practical ceiling commonly cited at 15–20 kW per rack. GPU thermal design power has climbed from roughly 400 W (A100, 2020) to about 700 W (H100), around 1,000 W (B200) and up to roughly 2,300 W on the 2026 Rubin platform.
Order books confirm that this is now execution rather than experimentation. AI-optimised server backlogs are measured in tens of billions of dollars, and third-party estimates put liquid-cooling penetration at approximately 53% in 2026, up from about 33% in 2025. In China, the liquid-cooled data centre market reached RMB 15.98 billion in 2025, up 45.2% year on year, and more than 80% of existing air-cooled facilities are considered candidates for retrofit.
Liquid cooling does not remove air-side equipment — it changes its duty. Rooms still need air distribution, dehumidification and make-up air, so dampers, actuators and room sensing stay in scope. What changes is the operating point:
- Secondary-loop (CDU) control. Modulating valves must hold a tight supply temperature at low flow, so selection shifts from pipe size to Cv at the actual design flow. An oversized valve that was acceptable on an older, higher-flow design can lose controllability at the bottom of its range.
- Defined fail positions. Redundant loops need actuators with a documented fail position and position feedback, because a valve that drifts closed during a changeover is a capacity event, not a comfort complaint.
- Supply/return ΔT as a KPI. Higher design ΔT is how liquid-cooled halls keep pumping energy down, which puts a premium on sensor accuracy — a few tenths of a degree of error in a ΔT measurement is a large percentage error.
- Live-hall retrofits. Because air-to-liquid conversions happen while the facility is running, components have to be specified, installed and commissioned without a shutdown window.
2. R290 Heat Pumps: What IFA 2026 Signalled
At IFA 2026 in Berlin (9 September), Midea presented its R290 natural-refrigerant range, including a compact indoor-only heat pump designed to remove the outdoor unit entirely, together with remote diagnostics for service. The company states it has sold more than 10 million R290 air conditioners since 2018.
The direction is consistent with the regulatory arithmetic. R290 has a global warming potential of about 3, against 675 for R-32 and 2,088 for R-410A. But R290 is classified A3 rather than A2L, which means the safety chain — charge limits, ventilation, leak detection and interlocks — is more demanding, not less.
Practically, that pushes work into the control layer:
- Leak-sensor inputs and a defined shutdown sequence (compressor, valve, fan interlock) must be wired and testable.
- Indoor-only designs concentrate more of the system inside the building envelope, increasing the number of sensors and the importance of defrost and capacity control logic.
- Remote diagnostics only pays off if the installed components report position, status and fault codes that a service platform can actually read.
For buyers, the takeaway is specification-driven: ask whether the controller supports the safety sequence the refrigerant requires, and whether the valves and actuators in the charge path have a fail position you can document.
3. Water-Side Hygiene Returns to the Headlines
On 9 September 2026, media reports described a legionella outbreak affecting 31 people in the Pamplona/Iruña region of Spain, with investigations centred on local cooling towers. The investigation is ongoing and no conclusion should be drawn about a specific installation.
What is not in doubt is the control-side response that cooling towers and evaporative condensers require: maintain water temperatures outside the range that favours growth, run a documented biocide programme, keep drift eliminators intact, and record the evidence. Controls contribute to all four:
- Temperature measurement on condenser water and basins, with accuracy appropriate to a compliance record, not just to a control loop.
- Motorised isolation and drain/flush valves so that cleaning and sampling can be scheduled without draining a whole loop by hand.
- Trend logging through the BMS, so that a history exists when an auditor or a customer asks for it.
Expect water-side instrumentation to appear more often in tender documents in Europe and the Gulf, where cooling towers carry a large share of the cooling load.
4. Two Quieter Signals Worth Watching
| Signal | What happened | Why it matters to component buyers |
|---|---|---|
| Institutional backing for low-GWP refrigerants | ASHRAE and UNEP renewed their memorandum of understanding on sustainable refrigeration and air conditioning (10 September 2026) | The refrigerant transition keeps its institutional momentum, so A2L/A3 readiness remains a multi-year specification requirement rather than a 2026 spike. |
| UK retrofit heat pump demand | Retrofit heat pump installations in UK domestic properties in H1 2026 were 22% below H1 2025 (10 September 2026) | Subsidy-led pull has weakened; the demand that remains is efficiency-led, which favours control upgrades over equipment replacement. |
| Product safety enforcement | A further recall of certain Amana window and through-the-wall air conditioners was announced on 6 September 2026 | Traceability and documentation are increasingly part of the buying decision for importers, not an afterthought. |
What This Means for Specifiers and Buyers This Quarter
| Shift | What changes in the specification | Component impact |
|---|---|---|
| Rack density | Selection moves from pipe size to Cv at design flow; ΔT accuracy becomes a performance KPI | Modulating ball valves and control valves; see our valve Cv calculator |
| A2L / A3 refrigerants | Safety interlock logic moves into the controller and must be testable | Sensors with defined output behaviour; actuators with a documented fail position |
| Water-side hygiene | Temperature monitoring and trend history move into scope | Duct and immersion temperature sensors, motorised valves; see DSTE-1001 duct temperature sensor |
| Weaker subsidy pull | Retrofit control upgrades instead of full replacement | A 0–10 V control layer that is easy to re-commission; see our analog signal calculator |
Summary
September 2026 points three parts of the industry in one direction: more instrumentation, more modulation and more documentation. The control layer — valves, actuators, sensors and the signals between them — is where each of those requirements is actually satisfied, which is why component selection is increasingly a project-risk decision rather than a line item.
FAQ
Q: Does liquid cooling mean air-side equipment is no longer needed?
A: No. Liquid cooling removes heat at the chip, but the hall still needs air distribution, dehumidification and make-up air. Dampers, actuators and room sensing stay in the scope of supply; only the duty profile changes.
Q: Is a 0–10 V control layer still usable in a liquid-cooled hall?
A: Yes. Most CDUs, valves and transmitters still accept 0–10 V or 4–20 mA, and bus integration remains optional. Verify input impedance and cable length before assuming a legacy signal will travel reliably.
Q: Do higher-density racks require different valve sizes?
A: Often, but by calculation rather than by rule of thumb. Higher design ΔT reduces flow, so a valve that was acceptable on a lower-ΔT design may become oversized and hard to control.
Q: What is the practical first step for a retrofit project?
A: Measure before specifying. Log supply and return temperatures and valve position for a week. Most retrofit control budgets are justified by what the trend log shows, not by the equipment list.
Work With DNARENS
DNARENS manufactures the control layer behind high-density, low-GWP and water-side projects: modulating damper actuators, motorised ball valves, control valves, 0–10 V temperature, humidity and CO2 transmitters, and FCU thermostats — from our own facility in Quanzhou, China, with OEM and ODM support. Every unit is 100% function-tested before shipment, and third-party certification can be arranged for the destination market on request.
Free engineering tools, no sign-up: valve Cv, damper actuator torque, FCU flow, analog signal and sensor range.
Send us your loop design, flow rate and target market and our engineers will come back with matched models and a quotation: Contact our engineering team.
Sources
Primary documents behind the standards, regulations and figures in this article. Links open in a new tab.
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