Old dial thermostat refusing to switch the boiler on? Programmer display dead, or stuck on permanent ON? We replace failed Honeywell, Drayton, and Salus controls across London and upgrade you to modern smart controls if you'd like.
Heating controls have moved a long way in the last decade. A 20 year old mechanical Drayton Lifestyle or Honeywell CM31 wired to a Sundial Plan still works the boiler in the most basic way (on or off, full output), but it cannot do load-compensation, weather-compensation, or anti-cycling, and that costs you money on every gas bill. A modern OpenTherm-capable controller such as the Honeywell T6, Drayton Wiser, Salus iT500, or Nest Learning Thermostat (3rd gen) talks to the boiler digitally, modulates the burner down to roughly 30 percent of rated output, and keeps the flow temperature low enough for the heat exchanger to condense properly. Customers typically report 8 to 15 percent gas savings after a Sundial-and-mechanical to OpenTherm-and-smart upgrade.
Our heating engineers carry direct replacements for the Honeywell ST9100, ST9400, CM707, CM927, and T6, the Drayton LP722, MiTime, and Wiser Hub, the Salus EP200 and iT500, and the Siemens RWB29 programmer. We replace any failed unit like-for-like, or fit a smart upgrade with full commissioning, app pairing, and a 15 minute hand-over so you actually understand the controls before we leave.
Where this service applies
- Failed mechanical Drayton, Honeywell, or Sunvic dial thermostat (heating stays off, or stays on permanently)
- Blank, frozen, or unresponsive programmer (Honeywell ST9100, ST9400, Drayton LP722, Siemens RWB29)
- Like-for-like replacement requested after a failed unit (no rewiring needed)
- Smart upgrade to Honeywell T6, Drayton Wiser, Salus iT500, Hive, Nest, or Tado
- Boiler upgrade to OpenTherm-capable model that needs a matching modulating controller
- Adding a weather-compensation outdoor sensor to a Vaillant ecoTEC, Viessmann Vitodens, or Worcester Greenstar
- Landlord upgrades for EPC improvement (Drayton Wiser TRVs across multiple zones)
- Salus iT500 GSM kit for properties with no WiFi (text-message remote control)
How we deliver
No surprises, no upselling. The exact path every job follows.
- 1
Existing controls survey
We identify your current programmer, room stat, cylinder stat (if fitted), and wiring centre, then check whether the boiler supports OpenTherm or load-compensation. - 2
Options presented
Like-for-like swap, modern programmable replacement, or full smart upgrade with app and zone control. Written quote for each option. - 3
Safe isolation
230V supply isolated at the spur or consumer unit. Voltage absence proved with a multimeter before any wiring is touched. - 4
Old unit removed, wiring labelled
Existing terminations photographed and labelled (L, N, LS, COM, NC, NO, OT+, OT-) so the new unit can be wired without guesswork. - 5
New unit fitted and wired
Whether a Honeywell T6 OpenTherm, Drayton Wiser Hub, Salus iT500, or simple mechanical replacement, wired to manufacturer instructions. - 6
Pair, programme, and test
Smart units paired to your home WiFi and the customer's account. Time, date, schedule, and frost protection set. Heat and DHW demands proved live. - 7
Boiler modulation verified
On OpenTherm pairings, we confirm the boiler is actually modulating output rather than firing flat-out. A simple but commonly missed commissioning step. - 8
Customer hand-over and notes
15-minute walkthrough of the controls, app installed on your phone, and a written job sheet with model and serial recorded for warranty.