We've been called in to fix dozens of underfloor systems installed badly by others. These are the most common errors — and how to avoid them.
The unfortunate truth about underfloor heating: it's easy to install badly, and very expensive to fix once the slab is poured. Mistakes made on day one can haunt the system for 30 years.
1. No heat-loss calculation. Installer guesses at pipe spacing, system runs hot or cold, can't be balanced. 2. Pipes too far from the slab surface — heat takes hours to reach the floor. 3. Insufficient insulation under the slab — heat goes down into the ground. 4. Manifold sized wrong — system can't be balanced room-by-room. 5. Wrong floor finish over high-output zones — timber cracks, vinyl warps. 6. No commissioning records — boiler is never tuned to the system.
Skipping the heat-loss calculation. Without one, the installer guesses at pipe spacing — and the system can't be balanced. We refuse to quote without a heat-loss calculation, every time.
Sometimes. If the issue is commissioning, controls or balancing — yes, we can re-tune. If the pipework is wrong (too far from slab surface, wrong centres, no insulation under slab) — usually only a partial fix is possible without major demolition.
Ask for: a heat-loss calculation, named insurance, references on past installs, a fixed-fee quote (not 'cost plus'), and commissioning records at handover. If they can't provide these, walk away.
"AHHAC delivered our 22-zone underfloor system on time, on budget and to spec. The crew were tidy, the documentation was thorough, and the commissioning was textbook."
"We've worked with AHHAC for 17 years. They've installed and serviced our hot water plant across three commercial buildings — and they pick up the phone on weekends."
"Three mobs quoted us; AHHAC's design was the only one based on a proper heat-loss calculation. The system runs beautifully — the others would've been oversized and expensive."