A boiler installation is a significant job — but for most like-for-like replacements, it's completed in a single working day. Here's a realistic guide to timelines.
Standard like-for-like combi replacement
Same location, same type of boiler: most experienced engineers complete this in 6–8 hours. You'll be without heating and hot water from when the engineer starts until commissioning is complete — typically by mid-afternoon for a morning start.
Combi replacement with additions
Adding a magnetic filter, new controls, repositioning the flue, or running additional pipework: allow a full day (8 hours). Some complex flue routes may require a second visit.
Switching boiler type
Converting from heat-only to combi (removing cylinder and loft tank, running new pipework): 1.5–2.5 days. Converting from combi to system boiler (adding cylinder): 1–2 days depending on cylinder position.
Full system replacement
New boiler plus all new radiators and pipework: 3–5 days for a typical 3-bed home. 5–10 days for a large 4–5 bed property with extensive work.
Our process on the day
Our engineers arrive at 8–9 am, give you a briefing on the day's work, and ensure you have hot water before leaving if the job continues to a second day. All paperwork and commissioning certificates are completed on site before leaving.