Do you have to replace radiators for a commercial heat pump?

The fear of ripping out every radiator and re-piping the whole building is one of the biggest reasons commercial buyers hesitate over heat pumps. It is also, in most cases, unfounded. The reality is more nuanced — and it starts with flow temperature.

Why flow temperature matters

A gas boiler typically pushes water around the building at 70-80 °C. A heat pump can do that, but it is most efficient at a lower flow temperature — 45-55 °C — because every degree of reduced flow temperature lifts the SCOP (the seasonal efficiency). The catch is that a radiator sized for 75 °C water delivers less heat at 50 °C, so to run cool you sometimes need larger emitters in the coldest rooms.

That is the whole question, and it is an engineering one — not “boiler or strip-out”.

The emitter survey comes first

Before we design anything, we survey the existing radiators, convectors, coils and pipework. That tells us, room by room, whether the building can run at a heat-pump flow temperature as-is, or where selective upgrades are needed. On many commercial systems the answer is that most emitters are already oversized enough to run at 50-55 °C, and only a handful of spaces — usually the coldest or highest-ceilinged — need larger units.

Crucially, this happens before the plant is ordered, so there are no mid-install surprises and no cost that appears out of nowhere on week three.

When high temperatures are genuinely needed

Some buildings — older stock with modest emitters, or process applications — really do need high flow temperatures. There, a full re-emittering would be expensive, so we use one of two routes instead:

• A high-temperature heat pump delivering 70 °C+ flow, so the existing emitters keep working.
• A hybrid (bivalent) design, where the heat pump covers 70-90% of annual heat and a peaking boiler tops up the coldest days. This suits buildings with high-temperature emitters and still cuts carbon 70-90%.

Both avoid stripping out the whole building.

What this means for cost

Because the emitter survey is done up front, the emitter upgrade — if any — is a known, budgeted line in the fixed-price proposal, not a risk. And because we design to the lowest workable flow temperature, the running cost is optimised: the SCOP is set as much by the emitters as by the heat pump itself.

The bottom line

You almost never have to replace every radiator. You need an installer who surveys the emitters, designs to flow temperature, and tells you exactly what needs upgrading before you commit — and who reaches for a high-temperature or hybrid design when a strip-out would not pay. That honesty is the difference between a heat pump that quietly underperforms and one that holds temperature and runs efficiently.

See how we handle hybrid and boiler-replacement installs, read the myths vs facts, or send your consumption data for a free feasibility.