Common questions

A single-room split system from Balmy costs from £2,100 fully installed, rising to £2,600 for a large 7kW room. That includes the indoor and outdoor units, pipework, a new electrical supply and trunking as standard. Our instant quote tool gives you an exact price for your home in a couple of minutes, with no site visit.

Modern inverter air conditioning costs the most in the first 15–30 minutes while it brings the room to temperature, then drops considerably once it's only holding it there. At around 26p per kWh, a single 3.5kW unit uses roughly 1kW flat out (about 26p an hour) but typically 0.3–0.5kW once the room is at temperature (around 8–13p an hour). A 2-way split on a 5kW outdoor unit is roughly 40p an hour at full power and 13–20p holding; a 3-way split on a 7kW outdoor unit roughly 60p at full power and 20–30p holding. The same applies in heating mode, where every 1kW of electricity delivers around 3–4kW of heat. Leaving the unit on at a steady setpoint is usually cheaper than switching it off and blasting it back on.

Often, yes. A split system in heating mode delivers around 3–4kW of heat for every 1kW of electricity used, so it's one of the most efficient ways to heat a single room. For heating a whole house with radiators, a gas boiler is still usually the cheaper option, which is why Balmy fits both.

The price you see on our quote tool is the total you pay. There is nothing added on top.

In the right room, yes. In some houses, no. It earns its keep in a bedroom you can’t sleep in during a heatwave, a home office you sit in all day, a south-facing living room or a loft conversion that bakes. Because every unit we fit heats as well as cools, it is also the cheapest way to warm that one room in spring and autumn without running the whole house. Where it is harder to justify is a small, shaded room you use for an hour in the evening. If that is your house we will say so. We would rather you spent the money on something you will use.

Ten to fifteen years is typical for a good split system that is serviced. The outdoor unit does the hard work and usually goes first; the indoor unit often outlasts it. An annual clean and check is what gets you to the top of that range. We do them for £120.

We would be guessing if we gave you a figure, and so is anyone else who does. What we can say is that buyers notice it, especially in a loft room or a bedroom that takes the afternoon sun, and a tidy, recent install with the paperwork is a selling point rather than a question mark. Treat it as something you buy for yourself that also helps when you sell, not as an investment.

No. The Boiler Upgrade Scheme grant is for air-source and ground-source heat pumps that heat the whole house and its hot water; the air-to-air units we fit are heat pumps too, but they don’t qualify. What you do get is no VAT on the installation until 31 March 2027, and a reduced 5% rate after that.

Once the room is at temperature a 2.6 kW bedroom unit ticks along at around 0.2 to 0.4 kW, roughly 6 to 10p an hour at today’s rates, so eight hours overnight is about 50p to 80p. Set it to 22 or 23°C rather than 18, use the sleep mode, and it will be at the bottom of that range. Our running-cost calculator on the air conditioning page lets you put in your own tariff.

Yes. Every system Balmy installs is a reversible heat pump: it heats in winter and cools in summer from the same unit. Modern units keep working efficiently well below freezing, so it's a year-round system rather than a summer-only one.

As a rough guide: 2.5–2.6kW for a small room such as a bedroom or home office, 3.5kW for a medium living room, 5kW for a large open-plan space and 7kW for very large rooms or extensions. Ceiling height, glazing and sun exposure all affect this, and the quote tool asks about each of them.

For most houses in England, no. Since May 2025 an air conditioning system that also heats counts as permitted development, provided the outdoor unit meets size, siting and noise limits, and every Balmy install is planned to meet the MCS 020 noise standard. Listed buildings, conservation areas and flats may still need permission. We will tell you if that applies to you.

Normally on an external wall bracket or on ground-level feet, as close as practical to the indoor unit. It needs a little clearance for airflow and access, and we position it to keep noise away from your neighbours' windows. Pipework runs are neatly enclosed in trunking as standard.

A single-room split system is usually installed in a day. Multi-split systems with two or more indoor units typically take one to two days depending on the pipework runs.

A single split is one outdoor unit serving one indoor unit, for one room. A multi split is one outdoor unit serving two to five indoor units, so you can cool and heat several rooms without multiple outdoor boxes on the wall. Balmy fits Haier and Bosch systems in both formats.

Quieter than most people expect. The indoor units we fit run from about 18 to 21 dB(A) on their lowest setting, quieter than a whisper, up to the high 30s flat out, which is a quiet fan. The outdoor unit is louder, in the mid-40s to mid-50s dB(A) close up, about the level of a fridge or quiet conversation, and we position it so the noise at your neighbour’s nearest window stays within the 42 dB limit the MCS 020 planning standard sets. The noise figures for each unit are on your quote.

Often, but there are two checks. Your lease almost certainly needs the freeholder’s or management company’s written consent before anything goes on the outside of the building, and flats don’t get the permitted-development allowance that houses do, so the outdoor unit may need planning permission. The practical question is where the outdoor unit can sit: a balcony, a flat roof, or an external wall you have the right to use. Send us a photo of the outside and we will tell you straight whether it can be done.

Yes. A solid brick wall is core-drilled for the pipework the same as a cavity wall, a 65 mm hole that is made good afterwards. What changes is the sizing: solid-walled houses hold more heat in summer and lose more in winter, so we tend to go a size up on the unit for the same room. The quote asks about the room and the sun it gets, so this is built in.

Once a year, the same as a boiler. The filters want a rinse every couple of months in summer, which you can do yourself in five minutes; the annual service is the coil clean, the condensate drain, a refrigerant pressure and leak check and an electrical check, and it is what keeps the manufacturer’s guarantee valid. An air con service with us is £120, booked online.

It helps, because cooling a room pulls water out of the air. A 3.5 kW unit will take a litre or more an hour out of a humid room in cooling mode, and most units have a dry mode that dehumidifies without cooling much. It will not fix the cause of damp, so a leak or rising damp needs sorting first. For a stuffy bedroom or a room that steams up, it makes a real difference.

A portable unit is cheap to buy and expensive to live with: it dumps its heat through a hose out of a window that then has to stay open, so it fights itself; it is noisy, because the compressor is in the room with you; and it takes up floor space. A fixed split puts the noisy part outside, uses far less electricity for the same cooling, heats in winter, and sits out of the way on the wall. If you will use it for more than a few days a year, fixed wins.

High on the wall, on or near an outside wall so the pipe run is short, and not pointing straight at the bed or the sofa. You want the air to sweep the room rather than blow on you. It needs about 15 cm clear above it and a route for the condensate to drain. We look at the room in your photos and suggest a spot; the quote also asks whether it is going on an internal wall, because that needs a small condensate pump.

Yes to all three, as long as it can be reached to service it and there is room for air to move round it. A flat roof or a garage is often the tidiest answer because the unit is out of the garden. On a balcony we use feet rather than a bracket and keep it away from the seating. The quote asks whether the unit is above ground-floor level because anything that needs access equipment is priced in, not sprung on you.

A straight combi swap from Balmy starts from £1,995 including VAT, boiler, installation, flue and sundries. The exact price depends on the boiler size, flue type and any extras like TRVs or a system clean. The instant quote gives you a fixed price before you book.

Converting from a conventional or system boiler to a combi starts from £2,667 including VAT with Balmy. The higher cost reflects the extra pipework and the removal of your hot water cylinder and tanks, which also frees up the airing cupboard and loft space.

Replacing an old G-rated boiler with a modern A-rated condensing boiler can cut gas use by around 20–30%, because the new boiler converts over 90% of the gas it burns into heat compared with 60–70% for older models. The exact saving depends on your home and how the old boiler was performing.

Once a year. An annual service keeps the boiler safe and efficient, and most manufacturer warranties require it to stay valid. Balmy offers boiler servicing across Hertfordshire, Buckinghamshire, Surrey and Bedfordshire.

Ten to fifteen years for a modern condensing boiler that is serviced every year, and plenty go longer. What shortens that is sludge in the system, hard-water scale in the heat exchanger and skipped services. That is why every boiler we fit gets a magnetic filter, why we offer a scale reducer on every quote, and why we nag about the annual service.

Not just because of its age. The signs it is time are repairs adding up, parts getting hard to find, a non-condensing boiler burning 20 to 30% more gas than a new one would, pressure that keeps dropping, or a boiler that struggles on cold mornings. If yours is fifteen-plus, out of guarantee and costing you a call-out a year, replacing it is usually the cheaper decision over the next five years. If it is ten years old and behaves itself, keep it and service it.

A useful rule: if the repair is more than about a third of the cost of a new boiler and the boiler is over ten years old, replace it. A single failed part on a younger boiler is a repair. We tell you which it is before quoting for the expensive option. We would rather fit a pump than sell you a boiler you don’t need.

All three are good boilers, which is why they are the three we fit. Worcester Bosch has the strongest name and the widest parts availability; Vaillant is the quietest and slimmest and suits a tight cupboard; Ideal is the value choice with a ten-year guarantee. The differences are smaller than the adverts suggest. What matters more is the size being right, a filter on the return, a clean system and an annual service.

For most households, no. Government energy-efficiency schemes have at times funded a replacement for people on certain benefits in homes with an old, inefficient boiler, and they run through the energy suppliers rather than installers; the schemes change, so the gov.uk “Help to improve your home” page is the place to check what is open now. There is no general grant for a gas boiler, and the £7,500 Boiler Upgrade Scheme grant is for heat pumps only.

£99, and you can book it online in a minute. A service is a strip-down check, flue gas analysis, safety checks and a written record, and it is the thing your manufacturer’s guarantee depends on.

For most homes with one or two bathrooms, yes. A combi heats water on demand so there's no cylinder, no tank in the loft and no waiting for the water to heat up. Larger homes with several bathrooms in use at once may be better off with a system boiler and cylinder. Our quote tool walks you through both options.

A 25kW combi suits most flats and smaller houses with one bathroom; a 30kW combi is the usual choice for family homes with one to two bathrooms. It's the hot water flow rate rather than the heating output that usually decides it, and we show the flow rate for each boiler on your quote.

Yes. Relocating a boiler is a common part of a replacement, often into a garage, utility room or loft. It adds to the cost because of the extra pipework and a new flue position, and the quote tool prices it for you if you select the relocation option.

A like-for-like combi swap is usually done in a day. A combi conversion or a relocation typically takes one to two days.

A combi heats water the moment you open a tap, so there is no cylinder and no tank in the loft, just one box on the wall. A system boiler heats a hot water cylinder, usually in the airing cupboard, but takes its water straight from the mains, so there is still no loft tank. A regular boiler, also called conventional or heat-only, heats a cylinder and is fed from a cold tank in the loft, with the pump outside the boiler. A combi suits most one- and two-bathroom homes; a cylinder suits homes running several showers at once.

Three things, and every manufacturer is the same: the boiler is registered with them within 30 days of installation (we do this for you), it is serviced every twelve months by a Gas Safe engineer with the service recorded, and it was fitted with a system filter. Miss a service and the guarantee lapses, which is the real reason to book one every year. Ours is £99.

A magnetic filter, always. It is on every boiler quote we do and most guarantees require one. A flush depends on the system: if the radiators are cold at the bottom or the old water runs black, that sludge will end up in the new heat exchanger, and we recommend a MagnaCleanse, which is a £240 option on the quote. A clean system in a younger house doesn’t need one.

Usually one of three things: a small leak somewhere on the system (often a radiator valve or a joint you can’t see), a tired expansion vessel inside the boiler, or a pressure-relief valve that is letting by. Topping up every week is a symptom, not a fix, and it drags fresh oxygen into the system, which corrodes it. In most cases it is a repair rather than a replacement, so give us a call.

For some houses, yes. We don’t fit them, so this isn’t a sales pitch either way. A heat pump suits a well-insulated house with large radiators or underfloor heating and space outside for the unit, and there is a £7,500 government grant towards one. A typical older semi round here with standard radiators and a combi will usually run more cheaply and more comfortably on a modern gas boiler for the next ten years. If you are insulating and changing the radiators anyway, look at a heat pump seriously; if you are just replacing a boiler, replace the boiler.

The engineer arrives at the agreed time, lays dust sheets, drains the system and takes out the old boiler, fits the new one with its flue, filter and controls, refills, tests and commissions it, then walks you through the controls. Water and heating are off for most of the day. A combi swap is usually done by mid-afternoon; a conversion or a relocation can run into a second day. Clear the cupboard and a path to it, and tell us where the van can park.

Yes. Removing and disposing of the old boiler, and on a conversion the cylinder and tanks, is in the price.

It does, and everywhere we cover is hard water. Scale builds up in the heat exchanger and, on a combi, in the plate exchanger that makes your hot water, so the boiler works harder, gets noisier and fails earlier. An inline scale reducer on the cold feed is a £36 option on every combi quote, and we would fit one in our own house.

Balmy covers Hertfordshire, Buckinghamshire, Surrey and Bedfordshire, working out of Watford. That includes St Albans, Hemel Hempstead, High Wycombe, Amersham, Guildford, Woking, Luton, Bedford and everywhere in between. If you are unsure, ask us.

Yes. Balmy is a trading name of Thermo Heating & Cooling Ltd, which is Gas Safe registered for boiler work and F-Gas registered through REFCOM for air conditioning. Registration numbers are shown in the footer of this site.

Yes, as long as your answers match what we find on the day. We review every quote before confirming and will only contact you first if something about your home is out of the ordinary. There are no hidden extras added on site.

Boilers come with the manufacturer's warranty: 5 years on the Worcester 1000, 10 years on the Worcester 4000, Greenstar Ri, Vaillant ecoFIT pure and Ideal Logic Max, and 2 years on the Ideal Logic Heat2 and System2. The Daikin, Bosch and Haier air conditioning units carry a manufacturer's warranty of 3 to 5 years. On top of that, every install has our 1-year workmanship guarantee.

Refrigerant is a controlled gas. By law anyone who connects, tests or recovers it has to hold an F-Gas qualification, and the company has to be certified, and ours is through REFCOM. It matters because an uncertified install has usually skipped the pressure test and the vacuum, which is where leaks and early failures come from, and because most manufacturers won’t honour a guarantee on a system fitted by someone unregistered. Ask any installer for their certificate; we will show you ours.