Heat Pump Running Costs Too High? Here’s Why
If your air source heat pump is costing far more to run than you were promised, the heat pump is usually fine — the settings are not. Optimisation visits across Orpington, Bromley, Sevenoaks and Kent.
paymentsOptimisation Visit
- check_circle£170 full service & optimisation, no VAT
- check_circleFlow temperature reviewed & set
- check_circleWeather compensation configured
- check_circleBefore and after readings recorded
- check_circleWritten report with the figures
Why It Costs More Than You Were Told
This is the single most common call I get about heat pumps, and it almost never turns out to be a broken heat pump. It is nearly always how the system was commissioned — and the good news is that settings cost nothing to change.
Flow temperature set too high
The big one. A heat pump's efficiency depends heavily on how hot it pushes water round your radiators — every degree higher costs you. Many systems are commissioned at 50°C or more because the house warms up fast on handover day and everyone is happy. The same house will often run perfectly well at 40–45°C.
Weather compensation switched off
It should raise flow temperature only as it gets colder outside, rather than running flat out all winter. It is built into virtually every modern unit. It is also disabled, or set with a curve that makes no sense for the property, on a great many of the systems I visit.
Text description of this diagram
The chart plots flow temperature against outside temperature, with colder conditions to the right. A red dashed horizontal line shows a system with weather compensation switched off: it runs at a fixed high flow temperature regardless of the weather, which wastes electricity on milder days. A green sloping line shows a weather compensated system: on a mild day it runs at a lower flow temperature, which is more efficient, and it raises the flow temperature only as the outside temperature falls. The curve shown is illustrative only; the correct settings depend on your property, its heat loss and the size of your radiators or underfloor system.
Being run like a gas boiler
Heat pumps are most efficient running steadily at low output. Deep overnight setbacks, or switching off during the day and boosting when you get home, usually costs more than it saves. This is an owner-side habit, not a fault, and it is easily corrected once explained.
Radiators never resized
If the emitters were left as they were for a gas boiler, the installer's only way to get heat into the house is a high flow temperature — which destroys efficiency. Sometimes the honest answer is that one or two radiators need upsizing, and I will tell you if that is the case rather than pretending settings alone will fix it.
Sludge and poor flow
A partially blocked strainer or a sludged system starves the heat pump of flow. It compensates by working harder. Repeated pressure top-ups are the warning sign, because every top-up introduces fresh oxygenated water.
Legionella cycle running too often
On systems with a cylinder, an over-frequent legionella cycle heats water to a high temperature far more often than necessary. Set sensibly it is a safety measure; set badly it is a quiet, constant cost.
How an Optimisation Visit Works
I take readings before I change anything, so there is a genuine baseline to compare against. Then I work through flow temperature, the weather compensation curve, controls and setback strategy, system pressure, expansion vessel charge, strainer and flow rate, and the cylinder settings if you have one.
You get the before and after figures in writing, along with an honest assessment. If the system genuinely needs hardware changes rather than settings, I will say so — I would rather tell you than take your money for an optimisation that cannot deliver.
Heat Pump Running Cost Questions
Get Your Heat Pump Costs Down
£170 with no VAT, before and after figures in writing, across Orpington, Bromley, Sevenoaks and Kent.
call07717 846247What Good Actually Looks Like
It helps to know what a well-set-up system should be achieving, because "high" is meaningless without a reference.
The measure that matters is COP — coefficient of performance, or how many units of heat you get per unit of electricity. A well-commissioned air source heat pump running at sensible flow temperatures should comfortably achieve a COP of 3 or better over a heating season. Push flow temperature up to 55°C and that can fall toward 2 or below, which means your heating bill is roughly half again what it needed to be.
That is the whole argument in one number. Nothing about the hardware changed — only the temperature it was asked to produce.
When I optimise a system I record flow and return temperatures, system pressure and the control settings before I touch anything, then again afterwards. You get both sets of figures in writing. If the numbers do not improve, I will tell you that too rather than claiming a saving I cannot evidence.
Where the Savings Actually Live
I record the numbers before and after, so the improvement is evidenced.
