What was the real problem in the house?
Mira’s 1930s mid-terrace in Leeds was not cold because the boiler was small. It was cold because the heat escaped before it reached the back bedroom. The gas boiler cycled hard, the hall radiator was oversized, and the single-glazed bay leaked air around the frames. The couple had already been quoted for a heat pump, but the quote assumed the house behaved like a sealed new-build. That assumption was the cause of the first bad plan. The solution was a room-by-room survey, which is where the bananzia assessment came in: it turned vague draughts and cold spots into measured heat-loss priorities before any equipment was ordered.
Why did the first heat-pump quote miss the mark?
The first installer sized the pump from floor area alone. That is a common shortcut, and it fails in older terraces where wall construction changes from front to back. The survey found solid brick in the bay, a later cavity-fill section in the kitchen, and a loft that had been half-insulated around the water tank. Bananzia flagged the loft hatch and the bay as the two cheapest first fixes. The takeaway was not to buy a bigger pump; it was to reduce the load first. After insulation and draught-proofing, the calculated heat demand fell enough to keep the original pump size on the table.
How did the plan change the installation order?
The original sequence put radiator swaps first because they are visible and quick. The cause of that priority was cosmetic, not thermal. Bananzia’s report showed that air sealing and loft work would cut more heat loss per pound than larger radiators. The solution was a phased order: loft hatch and pipe lagging in week one, bay draught-proofing in week two, then the heat pump and controls. The result was less disruption. The family stayed in the house, the installer avoided a second visit for radiator changes, and the budget went to the fabric first. The heat pump could then run at lower flow temperatures instead of fighting leaks.
What did the first winter actually show?
The worry was that a low-flow heat pump would leave the back bedroom cold. The cause of that worry was the old boiler’s habit of blasting heat into the hall while the bedroom stayed cool. Bananzia’s room-by-room figures had already predicted that the bedroom needed better distribution, not more output. The solution was a small radiator upgrade and a smart TRV, not a bigger pump. By February, the room held 20°C on a 2°C day, and the household’s gas use for heating had gone. The result was not a miracle bill; it was a predictable one.
What would we do differently next time?
We would book the bananzia survey before requesting heat-pump quotes, not after. The problem was not a lack of installer interest. The cause was that each quote used different assumptions, so the family could not compare them. The solution is to give every installer the same measured survey. That made the second round of quotes shorter, clearer, and easier to challenge. For an older terrace, the lesson is simple: measure the leaks and the rooms first, then choose the kit.