Combi vs regular boiler, and why regular is rarely the answer now.

How a regular boiler works

A regular (heat-only) boiler feeds a hot water cylinder with hot water. The cylinder is fed cold water from a tank in the loft, which is itself gravity-fed from the rising main. Two tanks, one cylinder, one boiler.

Regular boilers made sense when mains water pressure was low. The loft tank provided a reliable head of pressure for showers and taps, independent of the street mains. In most of modern Belfast, mains pressure is perfectly good, so the loft tank is no longer needed.

The case for regular

• Old pipework, very old homes with badly-routed pipework sometimes work better left as-is. Replacing an existing regular with a new regular avoids repiping.
• Low mains pressure, rural areas where the street pressure is under 1.5 bar. Rare in Greater Belfast.
• Multiple gravity showers, if you've got an old system that works well, ripping it out sometimes introduces more problems than it solves.

Why installers usually recommend against regular

• Lost space, loft tank takes up useful loft storage. Airing cupboard cylinder takes up ground-floor space.
• Freezing risk, loft tanks freeze in hard winters, causing floods when they thaw.
• Weight, full loft tanks put 200+ kg of water over your head. Joists need to cope.
• Lower efficiency, modern combis and system boilers run at higher efficiency than old regular setups.
• Resale, buyers are increasingly wary of loft tanks given the insurance history of tank failures.

What installers recommend instead

For most Belfast homes replacing an old regular boiler, the answer is one of:

• Combi, if one bathroom and good mains pressure. Ditches the loft tank and cylinder entirely. See the combi vs system guide.
• System boiler with unvented cylinder, if multiple bathrooms or larger home. Keeps the cylinder, ditches the loft tank, upgrades to mains pressure.

When you have to stay with regular

If you're insistent on keeping a regular system (or your plumbing genuinely needs it), Worcester, Vaillant and Ideal all still make regular boilers. They're fine, just not what the network typically suggests without a specific reason.