Job overview
A 3-bedroom house with an open-vent heating system and a hot-water cylinder had its boiler replaced. The boiler was a Vaillant system boiler. Honeywell S Plan controls. The manual radiator valves were upgraded with TRVs.
The system was converted to a sealed heating system with a system boiler. New controls were installed, as well as new wiring. The system was powerflushed and the radiator valves upgraded.
Components used
- Vaillant ecoTEC Plus 624 system boiler
- ST9400C programmer
- T6360 room thermostat
- L641 cylinder thermostat
- Honeywell zone valves
- Altecnic Ecocal TRV sets
Post-completion review
The customer was inclined towards a Vaillant 630 boiler. Using our experience we convinced them not to oversize the boiler, so we settled on a 624. Our calculations suggested even a 618 would have been more than enough, but sometimes people’s perceptions override a more correct solution because of fear. See what size boiler.
The preference is to have domestic hot water priority. In this property there will be tenants, and the landlord asked for everything to be kept as simple as possible.
Switching to an Altecnic Ecocal TRV is a solid and reliable valve. The seating can be replaced on a live system. See our TRV valve replacement article.
Related
- Case studies
- Vaillant
- System boiler
- S Plan and S Plan Plus
- Best radiator valves and TRVs
- How to repair a TRV with a service tool
- Priority domestic hot water
- What size boiler
- Choosing a new boiler
- How to service a Vaillant ecoTEC
- Vaillant ecoTEC exclusive 835 Green iQ case study
Project-specific install note from October 2019, not a DIY guide. Gas work in the UK needs a Gas Safe registered engineer. System water to BS 7593.