01Prices
Every seller's latest price
Sorted by price, then by the date we read it. One price type and grant state is compared; any other sits apart and says so.
Not checked yet
We have not read a price for this spec from any seller yet, so there is no figure here. These sellers are on our list for gas boilers; each price will show with its type, grant state and the date we read it.
02Index
The weekly index
The median of one price type across the sellers read in the last 14 days, week by week.
Index not started
The index needs three sellers with one price type, each read in the last 14 days, and two weeks of it to draw a line. It starts here once the weekly runs have that.
03Grants
Grants that can pay towards it
Grants differ by nation: each one says where it applies.
04Like for like
What counts as this spec
A seller's price is matched by its stated size and scope, never by price.
A system boiler of 15 to 24 kW replacing a system boiler in the same place, the hot water cylinder kept. A new cylinder or a conversion from a regular or combi boiler is off the comparison.
A price for a different size or scope is stored with the date we read it but kept off this comparison. A price after a grant is never put beside one before it without saying so.
05Questions
System boiler swap: questions
- System boiler swap: how much does it cost?
- System boiler swap: not checked yet. We have not read a price for this spec from any seller; the first weekly run fills it, every price with the date we read it.
- Which seller is cheapest?
- System boiler swap: we cannot say yet. No seller has a price read in the last 14 days, and we only call a seller cheapest on a reading from the latest weekly run.
- Is there a grant?
- Energy Company Obligation (ECO4) (pays for agreed work): England, Scotland and Wales only. Northern Ireland: none of the grants we track. Each grant page says who qualifies, checked on the official page.
- How are these prices read?
- From each seller's own website, once a week, with the date we read it. Every price says its type (from, fixed or typical) and whether a grant has been taken off. Commission never changes the order.
06Sources
Where these figures come from
- Energy Company Obligation (ECO4)checked 31/10/2026
- How we read prices