Boiler guide · Edinburgh

Combi, System or Regular Boiler: Which Is Right for Your Edinburgh Home?

The three boiler types heat your home the same way. The difference is how they supply hot water, and that decides which one suits your property. Here is a plain comparison.

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The short version

  • Combi boiler: heats hot water on demand straight from the mains. No hot water cylinder and no loft tanks. Compact and popular in flats and smaller homes.
  • System boiler: heats a separate hot water cylinder, so several taps can run at once. No loft tank for the heating, because the system is sealed. Suits larger homes with more than one bathroom.
  • Regular (heat-only) boiler: works with a hot water cylinder and a cold water tank in the loft. Often found in older homes and may be the simplest swap if that is what you already have.

Combi boilers

A combi gives hot water only when you open a tap, so there is no stored hot water to run out and no cylinder taking up space. The limit is flow: a combi can only heat so much water at a time, so running two showers together can reduce the flow at both. A combi also relies on your mains water pressure and flow rate, so it is worth having these checked before you commit.

System boilers

A system boiler needs a hot water cylinder but not the loft tanks. Because hot water is stored, it copes better when several outlets are used together. The cylinder needs space, and once it is empty you wait for it to reheat.

Regular boilers

A regular boiler is the traditional arrangement: a cylinder and a feed-and-expansion tank in the loft. If your home is set up this way, replacing like for like is usually the least disruptive option. Converting to another boiler type is possible but involves extra pipework and removing the old tanks and cylinder.

How to choose

  1. Count your bathrooms and how many people use hot water at once. More bathrooms and heavier demand usually point toward a system boiler with a cylinder.
  2. Check space. A combi needs no cylinder. A system or regular boiler needs somewhere for one.
  3. Have the water supply tested. Mains pressure and flow decide whether a combi will perform well.
  4. Look at what you already have. Keeping the same type is simplest. Changing type costs more because of the extra work.
  5. Get the size right. Boiler output (kW) depends on your home's heat loss and hot water demand, not just the number of bedrooms. A bigger boiler is not automatically better.

Get advice on your own home

The right answer depends on your property, so we survey first and recommend the type and size that fits. See our boiler installation service, read what affects the cost, or check whether an old boiler should be replaced.

More boiler guides

FAQs

Frequently Asked Questions

A combi heats hot water on demand from the mains and needs no cylinder. A system boiler heats water stored in a separate cylinder and suits homes that use several hot water outlets at once.

Often yes, because it is compact and needs no cylinder. Mains pressure and flow should be checked first, and the survey will confirm whether it suits your flat.

It is possible, but it involves extra pipework and removing the old tanks and cylinder, so it costs more than replacing like for like.

Not necessarily. Output should match your home's heat loss and hot water demand. An oversized boiler can be less efficient.

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Call McInally's or send us an enquiry. We survey your property, agree a fixed price, and fit and commission your boiler, with no hard sell.

Call 07449 984820 Book a Free Survey