Combi boiler conversion in Macclesfield
In short
Converting to a combi removes the cylinder and the loft tanks and gives you unlimited hot water at mains pressure — provided the incoming supply can deliver enough flow. Where the mains is weak, or two bathrooms run at once, the conversion makes the house worse rather than better.
Also called: convert to combi · remove hot water cylinder · back boiler to combi · system to combi conversion
The appeal is space and simplicity: the airing cupboard comes back, the loft tanks go, there is nothing stored to run out, and there is one appliance instead of a system of them. For a one-bathroom house on a decent mains supply, it is usually a genuine upgrade.
Flow rate is the deciding test, and it must be done before anything is agreed. A combi's hot water output is limited by the incoming mains, and the boiler's headline litres-per-minute figure assumes the supply can feed it. Measuring the actual flow at the kitchen tap takes minutes; a supply delivering well under the boiler's rating means a disappointing shower whatever the badge says.
The work involved is more than swapping an appliance. Cylinder and tanks come out, redundant pipework is removed or capped, the gravity-fed pipework that served them is repurposed or replaced, the system is converted to a sealed one with an expansion vessel and pressure relief arrangement, and the whole thing is cleaned before the new boiler is commissioned. On an old open-vented system, that clean is essential — decades of debris are about to meet a modern heat exchanger with narrow waterways.
The trade-offs deserve saying plainly. You lose stored hot water, so you lose the ability to run two showers at full flow simultaneously. You lose the immersion heater as a backup when the boiler fails. And in a house where the mains fails or is turned off, a combi gives you nothing while a cylinder still holds a tank of hot water.
Where the house has two or more bathrooms in genuine simultaneous use, the better answer is often a system boiler with an unvented cylinder: mains pressure at every outlet, strong simultaneous flow, and the cupboard space is the price. It is worth having both options quoted before committing.
What the job covers
- Mains flow and pressure test to confirm a combi will perform
- Removal of cylinder, loft tanks and redundant pipework
- Conversion to a sealed system with expansion vessel and PRV
- Full system clean or powerflush before the new boiler runs
- Making good where tanks and cylinder have been removed
- Commissioning, controls setup and Building Regulations notification
What it costs
We don't publish a price for this yet, because a number pulled out of the air is worse than no number at all — your plumber has to honour it. You'll get a firm price for your actual job when they ring you back, before any work starts. The quote itself is free and there's no obligation either way.
Common questions
How do I know if my mains supply is good enough?
It is measured, not guessed — flow rate at the kitchen tap in litres per minute, plus static pressure. If the figure falls well short of the boiler's rated output, either the supply pipe needs upgrading or a combi is the wrong choice.
Can I keep the cylinder as a backup?
Not usefully with a combi — the system is reconfigured and the cylinder has no heat source. If backup and simultaneous flow matter to you, a system boiler with an unvented cylinder is the better fit.
Need this doing in Macclesfield?
Tell us the job and it goes straight to our local plumber — one call back, usually the same day. Free quote, no obligation.