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A standard single-room split is fitted in one day. Multi-splits with three or more indoor units typically take two to four days.
In most cases, no. AC outdoor units fall under permitted development in England, provided the unit is placed at least 1m from the boundary and isn't visible from the road on a listed building. We'll confirm during the survey and handle any application on your behalf if needed.
Yes. Every system we fit is a heat pump, so you get efficient cooling in summer and cheap heating in shoulder seasons, typically producing around £5 of heat for every £1 of electricity.
A modern Daikin condenser runs at 45 to 50 dB on full tilt, quieter than normal conversation and around the level of a fridge humming. On quiet-mode at night it drops below 40 dB.
Not much. Based on today's Ofgem electricity price (around 25p per kWh), a bedroom unit costs roughly 7p an hour to cool and 11p an hour to heat. A lounge-sized unit is around 15p and 23p an hour. Cooling a whole 3-bed home on a hot day works out to about £1 to £2.50, and running the system for heating across a full winter typically costs £300 to £500, depending on how much you use it.
Because these systems are heat pumps, they give you about £5 of heat for every £1 of electricity, making them cheaper to run than an old gas boiler in mild weather. Electricity prices change every few months under the Ofgem cap, so your actual costs will go up or down slightly in line with that, but the 5-to-1 efficiency stays the same. We'll give you exact figures for your home during the survey.
Yes, because the heat pump component of an air conditioning system qualifies as energy-saving domestic equipment under current UK rules. Every install we quote carries 0% VAT until March 2027.
All our installs come with a manufacturer's warranty (typically 5 to 7 years on Daikin) and a 12-month workmanship guarantee on the installation itself.
Once a year is plenty for a domestic system. An annual service keeps the warranty valid, maintains efficiency, and catches small issues before they become expensive ones. We offer a fixed-price service plan if you'd like us to remember for you.
Yes. Modern heat pumps produce useful heat down to around -15°C outside, so they handle a UK winter comfortably. Output does drop in very cold snaps, which is why we size systems with that in mind during the survey.
Typically on an exterior wall, flat roof, or ground-mounted on anti-vibration legs. It needs airflow around it and a sensible route for pipework back to the indoor unit. We'll walk the options with you on the survey and flag anything that affects aesthetics or performance.
Usually yes, but you'll need freeholder consent before we start. We can provide spec sheets, and noise data.
A single split pairs one outdoor unit with one indoor unit, ideal for a single room. A multi-split runs two to five indoor units off one outdoor condenser, which saves wall space and is more cost-effective for whole-home cooling.
A ducted system is a concealed AC unit that cools a single room or connected space — for example, a master bedroom and its walk-in wardrobe, or a lounge that opens into a kitchen. The indoor unit is hidden in the ceiling void or a bulkhead or a wardrobe, and air is delivered through one or two slim grilles, so there's nothing visible on the wall.
A wall split is a visible unit fixed to the wall; a ducted system does the same job but stays out of sight. Performance is similar, but ducted looks cleaner and quieter in the room — the trade-off is that it needs ceiling void space and a bit more planning at install stage.
Only if the spaces are connected without a door between them, like a bedroom and en-suite walk-in wardrobe, or a lounge-diner. Once you've got separate rooms with closed doors, you really want a separate indoor unit per room — otherwise one space ends up cold and the other barely touched.
Both, but it's far easier when ceilings are open. In a finished room we usually need to drop a section of ceiling or build a bulkhead to house the unit and ductwork, plus make good afterwards. We'll show you exactly where it would sit at survey stage.
Typically 250–350 mm of void depth for the unit itself, plus a bit more for the duct runs. If you don't have that much loft or ceiling space, a bulkhead in the corner of the room is usually the answer.
No — this is one of the main reasons people choose ducted over wall splits in bedrooms. The fan unit is tucked away in the ceiling void with acoustic lining, and the grilles themselves are near-silent. Most clients say they forget it's running.
Yes. The systems we fit are reverse-cycle, so the same unit provides efficient heating in winter and cooling in summer — useful for a master bedroom you want comfortable year-round.
A domestic MVHR runs 24/7 and typically uses 20–40 W, costing roughly £40–£90 a year to run. In an airtight new-build it can save £100–£300+ a year on heating; in a leakier retrofitted home the savings are often much smaller.
If your property is a new build, a deep retrofit, or has an air permeability below around 5 m³/h·m², yes — Part F of the Building Regulations effectively requires a whole-house ventilation strategy, and MVHR is the most comfortable and efficient option.
Properly designed, no. At the unit we target below 35 dB, and at the supply valves you should hear nothing. Noise issues are almost always caused by undersized ducting or poor commissioning — we use rigid/semi-rigid ducts and balance every valve.
Very little. Filters are swapped every 6–12 months (you can do this yourself in two minutes) and the heat exchanger core is rinsed in the sink once a year. We offer an annual service plan if you'd rather we handle it.
A typical domestic MVHR installation runs £3,500–£8,000 for a 3–4 bed home, including unit, ductwork, valves, commissioning and certification. New builds sit at the lower end; retrofits cost more because of the extra work routing ducts through finished spaces.
Absolutely. MVHR doesn't lock you in — open the windows whenever you like. The system simply works less hard while they're open and returns to balanced ventilation when they're closed.
No — MVHR isn't a heating or cooling system. It recovers up to 90% of the heat from outgoing stale air and transfers it to incoming fresh air, so you lose far less warmth through ventilation. In summer, an automatic bypass diverts air around the heat exchanger so the house doesn't get pre-warmed, but it won't actively cool.
Yes, and we do it regularly. The bigger challenges are routing ductwork through finished ceilings or floor voids and improving airtightness so the system pays back — without those, performance suffers. We'll survey the property and tell you honestly whether it makes sense.
Yes — this is one of the biggest reasons people install it. MVHR continuously extracts moist air from kitchens, bathrooms and utility rooms before it has time to condense on cold surfaces, which is what causes black mould.
As standard, units come with G4 filters which catch dust, insects and larger particles. For pollen, PM2.5, traffic soot and finer allergens, we can fit F7 or ePM1 filters on the supply side on request — a worthwhile upgrade for anyone with hayfever, asthma, or living near busy roads.
The unit is roughly the size of a tall fridge cupboard (typically 600–700 mm wide and 700–900 mm tall) and lives in a loft, utility room, plant room or airing cupboard. It needs power, a condensate drain, and access for filter changes — we'll find the best spot during the survey.
A well-installed MVHR system lasts 15–20 years, and the heat exchanger core itself has no moving parts. Manufacturer warranties are typically 2–7 years on the unit, plus our own workmanship guarantee on the installation.
Cosy Flow is a residential specialist in heating installation, air conditioning, and ongoing servicing and repairs. Whether you're replacing an old system, fitting AC for the first time, or keeping your existing setup running reliably, we handle the job end to end, from initial survey through to commissioning and sign-off.
Yes. We're F-Gas certified, which is a legal requirement for anyone handling refrigerant in cooling systems, and we're manufacturer-approved installers, meaning we're trained and authorised to fit, commission, and guarantee the equipment we supply. Full public liability insurance is in place on every job.
We do. Every quote is free and no-obligation. Tell us a bit about your property and what you're looking to do, and we'll arrange either a site visit or a remote quote depending on the scope of the work. No pushy sales calls afterwards.
Every install comes with an extended warranty covering both parts and our workmanship. The exact length depends on the system and manufacturer, but we'll walk you through it clearly before you sign anything. No buried small print.
Most residential jobs wrap up in 1 to 3 working days depending on complexity. We work cleanly, with dust sheets down, tools tidy, and the site left as we found it. You'll get a realistic timeline in the quote so you can plan around it.
We cover the whole of Greater London, along with the surrounding areas. Not sure if you're in range? Drop us a line and we'll let you know before you spend any time on a quote.
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