More photos. More graphics. Same heating-first story.

The house baseline is the interesting bit: central heating keeps the whole home at 19.5°C, and the Vortex picks up the slack in the living room, nudging the occupied comfort zone to about 20–21°C when you want extra warmth exactly where you sit.

Heating the air is easy. Heating the room is the hard bit.

Take a perfectly ordinary living room measuring 4m × 4m × 2.4m. That is 38.4m³ of air. Start at a chilly 14°C and aim for 20°C: a 6°C rise.

14°C → 20°C, 5°C outside, 1.95kW heater.

Below are three plausible modelled rooms of the same size. The heater is identical; the building changes.

Every heater has a temperature it simply cannot beat.

At steady state, heater output equals room heat loss:

Once the room is warm, the heater only needs to replace the heat leaving the room. For the average 90W/K example with 5°C outside:

In this model, each extra degree adds about 90 watts of continuous heat demand. At 26.32p/kWh that is around 2.37p per hour per extra degree while that outside temperature persists.

A robust worked example with no scripts required.

For a 4m × 4m × 2.4m room, starting at 14°C, target 20°C, outside 5°C, and using the average-room assumptions from this article:

These are modelled values, not a promise of exact performance. Actual results vary with wind, glazing, draughts, adjacent-room temperatures, solar gain, central heating contribution and thermostat position.

Where the V-Fan sits changes how quickly the room feels warm.

The NIX cold-room routine.

At the Ofgem October–December 2026 average electricity unit rate of 26.32p/kWh, a continuous 1.95kW draw costs:

But once the thermostat cycles, the relevant number is average duty cycle. In the average-room example at 20°C with 5°C outside, the room needs about 1.35kW to hold temperature, or roughly 69% of maximum output. That is around 35.5p/hour in the model.

And why that is useful.

The house does the heavy lifting. The Vortex picks up the slack.

My house is already centrally heated to a background temperature of 19.5°C. That matters, because the Vortex is not being asked to drag a stone-cold room all the way from winter temperatures up to comfort on its own.

Instead, the central heating establishes the thermal baseline for the whole house, while the Vortex acts as a local comfort heater in the living room. Its job is to pick up the slack: take the occupied zone from roughly 19.5°C to around 20–21°C, improve air movement, reduce local cold spots and make the room feel properly comfortable without turning the whole-house thermostat up.

This also changes the economics dramatically. If the room only needs another half to one degree of lift, the Vortex is working as a targeted trim heater rather than a primary heating system. In practical terms, that is exactly where a portable electric heater makes the most sense: heat the occupied room a little more, rather than heating every room in the house more.

20°C + oscillation is not a magic setting. It is a very sensible engineering compromise.

The V-Fan has enough power to be a serious room heater, but whether it can actually heat a room depends on the room's heat loss. In a decent room, 1.95kW gives useful reserve capacity. In a very leaky room on a cold day, it can spend all day at maximum and still lose the fight.

That is why my default strategy is 20°C, oscillation ON, unrestricted intake, open throw across the occupied area, and then watch whether the thermostat begins cycling. Cycling means the heater has moved from “catch-up” into “maintenance”. That is the point where comfort and cost finally become predictable.

We can estimate the room’s real heat loss from its own behaviour.

The earlier sections use assumed heat-loss coefficients. The next step is much better: measure the room and infer H from real data. You do not need laboratory equipment. A reasonably stable indoor temperature sensor, an outside temperature reading, a clock and the V-Fan are enough to get surprisingly useful results.

Method A — steady-state duty-cycle test

This is the cleanest method if the room has already reached a stable temperature. Suppose the room is holding 20.0°C, outside is 5.0°C, and over a measured hour the heater is actually energised for 42 minutes.

That one experiment would put the room almost exactly into the “average” example used earlier. It also means that every additional 1°C of indoor/outdoor temperature difference costs roughly another 91 watts continuously.

The same room becomes a completely different heating problem as the weather changes.

Using an inferred room heat-loss coefficient of 91W/K, we can predict the average heat required to hold 20°C:

At around -1.4°C outside, a 91W/K room needs the full 1.95kW simply to hold 20°C. Below that, the V-Fan alone mathematically cannot maintain 20°C indefinitely.

This number is hugely useful because it turns the appliance from a vague “1.95kW heater” into something you can match against the actual building.

One degree sounds trivial. Thermally, it is not.

For a 91W/K room, raising the target from 20°C to 21°C adds about 91W of continuous load. At 26.32p/kWh:

That does not mean “never use 21°C”. Comfort matters. It means you can now see the trade in real units: if 20°C is comfortable, there is no engineering reason to run 21°C. If 21°C materially improves comfort, the price of that extra degree is measurable rather than mysterious.

A heater does not heat a perfectly mixed box.

The thermostat display might say 20°C while your ankles are at 18°C and the air above head height is 22°C. That is stratification. Portable fan heaters reduce it, but they do not abolish it.

For room testing, a separate thermometer around seated chest height, away from direct discharge, windows, doors and radiators, gives a much better representation of lived comfort.

Oscillation is really about reducing temperature variance.

When oscillation is ON, the average room heat input does not rise. What can improve is the spatial distribution of that heat.

This is why my default remains oscillation ON for room heating. The exception is deliberate personal heating, where concentrating the jet can produce more perceived warmth for the same electrical input.

Usually no. It changes delivery, not the electrical heater rating.

The PTC element has a finite electrical input. Higher airflow can carry that heat away from the element faster, so the outlet air may feel less scorching while the total heat delivered to the room remains broadly governed by the heater power and its controls.

The important point is that “hotter-feeling air” is not necessarily “more watts into the room”. A slower jet can feel hotter because each kilogram of air receives a larger temperature rise.

Where does the first few kilowatt-hours actually go?

Imagine our average room uses around 7.6kWh during a long 14→20°C recovery. The air itself only accounts for about 0.08kWh. The rest is a mixture of:

This is why the first warm-up after a house has been cold for a day can be dramatically slower than reheating the same room after a short setback.

14°C to 20°C is a different job from 18°C to 20°C.

Using the same average-room model, the second situation requires far less stored energy to be replaced.

That is the engineering logic behind background heating. It is not necessarily cheaper to keep everything warm all day, but avoiding a very deep setback can massively reduce the time required for a portable heater to restore comfort.

A repeatable protocol, not random temperature screenshots.

Turn the heat off and watch the house reveal itself.

When internal heating is off, the simplified room model becomes:

The room's temperature difference to outside decays approximately exponentially. If we already have an estimate of thermal capacitance C, the cool-down curve can estimate H. Or if H is known from a steady-state heater test, the curve can estimate C.

For example, if the room falls from 20°C to 18°C over two hours while outside stays close to 5°C, the decay ratio is:

That is not enough by itself to completely characterise the building, but paired with a heater-duty test it becomes extremely powerful.

A dirty filter does not make electricity disappear, but it can wreck airflow.

The V-Fan draws room air through the lower intake and filter before pushing it through the heating system. As filter resistance rises, airflow can fall. That changes how effectively the machine mixes the room and can alter outlet temperature and internal control behaviour.

For heating, the practical maintenance rule is simple:

This is where electric resistance heat can make strategic sense.

A 1.95kW resistive heater does not beat another 1.95kW resistive heater by some secret efficiency trick. Almost all of the electrical energy consumed in the room ends up as heat. The economic advantage comes from where and when you choose to heat.

If the alternative is raising several rooms by 1–2°C just to make one occupied living room comfortable, a local heater can sometimes win despite expensive electricity because it avoids heating unnecessary space.

What I would do, in order.