Glow-worm boilers.

What Glow-worm are good at

Vaillant engineering at a lower price. Shares parts and service networks with its parent, which is a real advantage over an unknown budget name.

What to watch

Entry models are basic. The longer warranties are on the upper range only.

Who they suit

Budget-conscious replacements where you still want a parent company that will exist in ten years.

What a Glow-worm actually costs

£1,900 to £2,600 fitted for a like-for-like combi swap in an average home, including the appliance, the labour, the flue, standard controls and VAT.

You will see lower numbers quoted elsewhere. Those are almost always the price of the appliance alone, at trade, and no homeowner pays that. Treating the box price as the cost of a new boiler is the single most common reason people are shocked by their first quote. Moving the boiler, removing a cylinder or a system flush all sit on top - the cost guide breaks it down.

The honest bit

Between the brands on this site the differences are real but modest. Who fits it matters more than what they fit. A mid-range boiler installed properly will outlast a premium one installed badly, every time, and most early failures are installation rather than manufacturing.

Which is the argument for getting three engineers to look at your house and tell you what they would put in it. It is free, it takes thirty seconds, and it is the only way to find out what the job is actually worth.