Edinburgh's tenement flats are beautiful, characterful homes — but they come with unique heating challenges. Thick stone walls, limited cupboard space, shared stairwells, and quirky pipework layouts mean boiler installations in tenements need careful planning and experienced engineers who know these buildings inside out.
This is the story of a real boiler replacement we carried out in a second-floor Morningside tenement flat. We've anonymised the homeowner's details, but every other detail is exactly as it happened.
- Property
- 2-bed tenement flat, Morningside
- Old Boiler
- 22-year-old Potterton back boiler (behind gas fire)
- New Boiler
- Vaillant ecoTEC Plus 30kW Combi
- Total Cost
- £2,650 (fixed price, fully installed)
- Installation Time
- 1.5 days
- Warranty
- 10 years (manufacturer-backed)
The Situation
The homeowner contacted us after their 22-year-old Potterton back boiler — hidden behind a gas fire in the living room — failed for the third time in two years. They'd spent over £600 on repairs in the past 18 months, and the boiler was no longer heating the flat evenly. The back bedroom radiator barely got warm.
The old system was a regular (heat-only) boiler with a hot water cylinder in the hall cupboard and a cold water tank in the roof space. The homeowner wanted to free up the cupboard space and simplify the system.
The Survey
We visited the flat for a free survey and spent about 40 minutes assessing the property. Key things we looked at:
- Flue routing — the biggest challenge in any tenement installation. The new boiler would go in the kitchen, so we needed a flue route through the external wall. Fortunately, the kitchen had an external wall facing the drying green (rear of the building), so flue routing was straightforward.
- Gas pipe size — the existing gas pipe from the meter to the living room was 15mm, which is insufficient for a modern combi boiler. We'd need to run a new 22mm gas supply to the kitchen.
- Condensate drainage — modern condensing boilers produce acidic condensate that needs to drain away. The kitchen had a sink waste pipe nearby, so this was an easy connection.
- Radiator condition — we checked all six radiators for sludge and corrosion. They were in reasonable condition but would benefit from a chemical flush.
A proper survey is essential in tenement flats. Online "instant quotes" can't account for gas pipe sizing, flue routes through stone walls, or condensate drainage — all of which affect the final price and feasibility.
Installation Timeline
Day 1 — Morning: Removal and Preparation
We arrived at 8:30am and started by isolating the gas and water supplies. The old back boiler and gas fire were carefully removed from the living room — this is always a dusty job in tenements, so we laid protective sheeting across the hallway and living room. The hot water cylinder was drained and removed from the hall cupboard, and the cold water tank in the roof space was disconnected and removed.
Day 1 — Afternoon: Pipework and Flue
With the old system stripped out, we ran the new 22mm gas supply from the meter to the kitchen, routed new flow and return pipework, and core-drilled through the external stone wall for the flue. Tenement walls are typically 400–600mm thick, so this takes longer than in a modern build — about 45 minutes per hole with a diamond core drill. We sealed the flue terminal neatly on the outside to maintain the building's appearance.
Day 2 — Morning: Boiler Installation
The new Vaillant ecoTEC Plus was mounted on the kitchen wall, connected to the gas, water, and condensate drainage. We fitted a MagnaClean Pro2 magnetic filter to protect the new boiler's heat exchanger from system sludge, added Sentinel X100 inhibitor to the system, and connected the new Honeywell T6 programmable thermostat.
Day 2 — Afternoon: Testing and Handover
The system was filled, pressurised, and tested. We ran the boiler through a full commissioning sequence, checked every radiator for heat output, tested the hot water flow rate, and verified the flue gas readings. Everything was documented and the Gas Safe certificate was completed. We walked the homeowner through the new controls, set the timer for their routine, and left them with all the warranty documentation.
The Challenges
Every tenement installation has its quirks. In this case:
- Stone wall drilling — the kitchen wall was 500mm of solid sandstone. Core drilling took longer than usual, but we used water-cooled diamond bits to minimise dust and noise for the neighbours.
- Capping the old fireplace — with the back boiler removed, the fireplace opening needed to be properly sealed and a ventilation plate fitted to comply with building regulations.
- Stairwell access — carrying equipment up a shared tenement staircase to the second floor requires careful planning. We used protective coverings on the stairs and completed all equipment transport first thing in the morning.
The Result
The homeowner gained a modern, efficient combi boiler with a 10-year warranty, freed up a full cupboard (previously occupied by the hot water cylinder), and eliminated the need for a cold water tank in the roof space. Their gas bills dropped noticeably in the first month — a 22-year-old back boiler running at roughly 70% efficiency replaced by a new unit running at 93%.
Six months on, the homeowner reported that the flat heats up in a fraction of the time it used to, hot water is instant (no waiting for a cylinder to heat), and the back bedroom — which was always the coldest room — is now properly warm.
Edinburgh tenement installations are our speciality. We work in them every week across Morningside, Bruntsfield, Marchmont, Stockbridge and Leith. If you live in a tenement, you need an installer who understands these buildings.
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