What a combi boiler gives you
A combi boiler heats water directly from the mains whenever a tap or shower calls for it, so there's no hot water cylinder and no cold water tank in the loft. That frees up the airing cupboard, removes the risk of a loft tank leaking, and means you only heat the water you actually use.
The trade-off is that a combi has a finite flow rate. One shower at a time is fine in most homes; two showers running together can stretch a smaller unit. Choosing the right output for your household is the part that matters most, and it's where a proper survey earns its keep.
Converting from a conventional system
Plenty of the homes we work in still have a gravity-fed system: a boiler, a hot water cylinder and tanks in the loft. Converting to a combi means removing the cylinder and tanks, re-routing pipework so the boiler feeds the taps directly, and making sure the mains pressure and flow at your property are up to the job.
A conversion is more involved than a straight swap, but it's a well-understood job. We check your incoming mains flow first, because a combi can only deliver what the supply brings in. If your mains flow is modest, we'll tell you honestly and talk through the alternatives, such as a system boiler with an unvented cylinder, rather than fit something that disappoints you.
Is a combi right for your home?
Combi boilers suit most smaller and medium-sized homes well, particularly where one bathroom is in use at a time and loft or cupboard space is at a premium. Larger households with several bathrooms running at once are often better served by a stored-hot-water system.
Our combi boiler installation guide walks through what happens on install day, and the new boiler cost guide explains what drives the price. When you're ready, we survey the property and give you a clear written quote before any work is booked.
How the installation runs
- Survey: we check your mains water flow, existing pipework and how your household uses hot water.
- Recommendation: the right output and model for your home, explained in plain English.
- Quote: a clear written price before anything is agreed.
- Fitting: old boiler out, new combi in, pipework tidied, system flushed and tested.
- Handover: we show you the controls and explain the servicing the boiler needs.
Looking after a combi
Combi boilers work hard, because every hot tap runs through them. Where water is hard, limescale can build up inside the heat exchanger, so we may suggest a scale reducer or system filter to protect it. An annual boiler service keeps the boiler efficient and is usually a condition of the manufacturer's warranty.
We are Viessmann and Grant installers, which lets us offer manufacturer's warranties of up to 10 years on qualifying installations. For wider system work, see our boiler installation page.
Areas we cover
We install combi boilers across Harpenden, St Albans, Redbourn, Wheathampstead, Luton and Hemel Hempstead, plus the villages in between. The full list is on our areas we cover page.