How to get an accurate new boiler quote
Without wasting time (London reality)
Most people don’t mind paying for a new boiler. What they hate is the back-and-forth, vague “from £X” numbers, and quotes that change once someone finally sees the setup. If you’ve been tempted by ultra-low prices, it’s worth seeing why cheap boiler installation quotes often fall apart in London once the real conditions are checked.
The fastest accurate quotes come from one thing: the right information upfront. This page explains what we actually need, when a survey matters, and how to avoid surprises. For pricing ranges, use the full new boiler cost guide for London.
The goal is the same quote before and after the job starts.
Most boiler replacements can be priced accurately from clear photos.
Relocations, conversions and managed flues usually need a visit.
Why boiler quotes are often vague
A boiler quote isn’t just “boiler + labour”. It’s “boiler + everything around it”. In real homes, the new boiler installation cost depends heavily on the constraints around the swap — so two properties can choose the same model and still get different quotes.
- Gas pipe size: older supplies often need upgrading for modern combis
- Flue constraints: clearances, terminal positions, balconies and neighbouring windows
- Pipework condition: microbore restrictions, sludge, old valves and poor flow
- Access: cupboards, stairs, parking permits, building rules (London reality)
- Relocation: moving the boiler changes the job completely
If an installer can’t see these, the quote will either be vague or padded “just in case”.
The photo checklist that gets you an accurate quote fast
For most straightforward replacements, photos are better than a rushed visit. They let us check the setup properly, not guess.
| What to send | Why it matters |
|---|---|
| Front of your boiler | Confirms current type (combi/system/heat-only) and likely swap complexity |
| Pipework underneath (close + wider shot) | Shows valves, filters, gas pipe sizing clues, and whether upgrades look likely |
| Flue connection inside | Helps confirm route, orientation and common constraints in flats/conversions |
| Flue outside (if accessible) | Checks terminal position relative to windows, balconies and boundaries |
| Quick note: flat/house + bathrooms | Lets us size the boiler sensibly and avoid underpowered recommendations |
“From £X” quotes that grow once the installer notices the gas pipe is undersized, the flue can’t go where expected, or the cupboard needs half the pipework reworked to be safe and serviceable. This is also how a boiler replacement cost quietly creeps up — not because the boiler changed, but because the surrounding work wasn’t allowed for.
When a survey actually matters
Some jobs genuinely need eyes on-site. The trick is knowing when.
- Boiler relocation (new pipe routes, new flue position, new condensate route)
- Boiler type conversion (heat-only/system → combi or combi → system)
- Managed/shared flues in flats (permissions and technical constraints)
- Very old/modified systems (legacy pipework that needs verifying safely)
A proper quote process uses surveys selectively — not as a default time-waster.
How to spot a “good” quote vs a time-wasting quote
A good quote usually includes
- Clear scope (what’s included and what isn’t)
- Boiler model and output (and why it’s suitable)
- Notes on likely upgrades (gas pipe, filter, flush, flue constraints)
- A realistic installation window (not wishful thinking)
A time-wasting quote usually looks like
- “From £X” with no mention of pipework, flue or system condition
- No questions asked about the property
- No explanation of what could change the final price
If you want to understand the bigger pricing picture (not just quote accuracy), use the new boiler cost and installation guide for London. And if you’ve ever wondered why one “like-for-like” quote lands hundreds (or thousands) apart, this breakdown helps: why new boiler prices vary so much .
Send the photo checklist + your postcode and we’ll tell you if it’s a simple swap, or one of the jobs that needs a proper survey before anyone throws numbers around.