Oct. 12, 2026
The question specifiers are starting to ask
For decades the hydronic circuit in a building has done one job: heating. Heat pumps changed that. The same water circuit that carries warm water into a floor slab in January can carry cool water through the same slab in July — and the pipe, for the most part, does not change. What changes is how carefully the design has to be controlled.
This is not a fringe idea. RITABLE's documented PE-RT pipe applications include radiant heating and cooling systems, chilled water systems, snow and ice melting, geothermal heat pump systems and solar water heating — alongside conventional hot and cold water distribution and underfloor heating.
But "the pipe can do it" is not the same as "the system will work." Here is what actually decides it.
1. Cooling reverses the principle — and inverts the risk
In heating, the risk outside the pipe is uneven output. In cooling, the risk is different in kind, not degree.
A chilled slab cools the room mainly by radiation and convection at its surface. If that surface drops below the dew point of the room air, moisture condenses on it. A damp floor in a cooling season is not a comfort complaint; it is a moisture problem — and in the wrong building, a mould problem.
The consequence is a design rule, not a preference: the cooling supply temperature is limited by the dew point of the space. That is why radiant cooling is properly treated as a sensible cooling system — it removes part of the load, and is normally paired with a ventilation system that handles dehumidification and fresh air. Specified that way it is quiet, draught-free and efficient. Specified as a replacement for air conditioning, it is a warranty claim waiting to happen.
2. Why the pipe still matters
Three properties decide whether a pipe is suitable for a dual-mode circuit:
Oxygen tightness. In a closed circuit — and especially a circuit shared with a heat pump, a manifold and a heat exchanger — oxygen diffusing inward through the pipe wall corrodes the metal components. That is what the EVOH barrier layer is for: an ethylene-vinyl alcohol copolymer layer that blocks gas permeation through the pipe wall, protecting the system's metal parts from the inside out. RITABLE supplies PE-RT pipe with an EVOH layer and PE-Xa pipe with an EVOH layer. In a heating-only system this is good practice; in a cooling system that runs cold for months at a time, it is closer to a requirement.
No tuberculation. Iron pipe scales and corrodes from the inside; over decades the internal surface roughens and heat transfer degrades. Polymer pipe does not. The documented advantage lists for RITABLE PE-RT pipe include "resistance to corrosion, tuberculation and deposits" — which matters more, not less, when the same circuit is expected to perform in cooling mode with cold water.
Flexibility and joint count. Every joint is a risk, and in a slab it is an inaccessible risk. Flexible pipe allows long, continuous runs with the spacing the design calls for.
3. The rest of the system is the same as heating
Nothing exotic is required. A dual-mode installation uses the same components as a heating system:
Pipe — 16, 20, 25 and 32 mm OD in the PE-RT range (documented to ISO 22391, CE certified), or PE-Xa where higher temperature ratings are wanted.
Manifold — distribution, control, balancing and monitoring functions; the RITABLE manifold range covers 2 to 8 outlets per unit in the JA series.
Modules and supports — the floor heating module uses a clip system to hold pipe at the specified spacing, and carries load and sound-dampening benefits.
Controls — the difference between a working cooling system and a failed one is usually here: surface temperature sensing, dew-point control and a changeover sequence that prevents the slab from being chilled while the space is still humid.
4. Where radiant cooling fits — and where it does not
5. Specification checklist for a dual-mode system
Confirm the pipe is rated for cold water service as well as hot — not all pipes carry both ratings.
Specify an oxygen barrier for closed circuits, particularly those serving metal components.
Establish the room dew point and set the cooling supply temperature limit from it.
Confirm what handles dehumidification — this is a system decision, not a pipe decision.
Plan condensate and control provisions at the manifold.
Confirm the pipe spacing works for the cooling load, not just the heating load.
The pipe is the part that has to last
Control strategy, sensors and valves will be replaced or upgraded over the life of a building. The pipe embedded in the slab will not. Whether the system heats, cools, or does both, the pipe is the one component worth specifying once and specifying well.
