Alpha boilers
Alpha Heating Innovation is a boiler maker based in Kent. It started in 1966, and its head office is at Wrotham Heath. Alpha is part of the Immergas Group. Immergas is a family-owned Italian firm, founded in 1964 in Brescello. Alpha says Immergas has made more than 8 million boilers.
Newer Alpha gas boilers end in NX. The E-Tec Plus NX is the top combi. The E-Tec NX and the smaller Evoke NX are combis too. The E-Tec NXS is the system boiler. The E-Tec Regular works with a cylinder and tanks in the loft. Alpha also sells the E-Tec Hybrid, which pairs a boiler with a heat pump.
How Alpha boilers show a fault
Many Alpha boilers show faults with coloured lights on the control panel. Each light may be on, off or flashing. The pattern tells you what’s wrong, but it changes from model to model.
Alpha has an online troubleshooter for this. You pick your boiler from a list, and it shows the lights for that model. Then you match the pattern you can see. The list covers Alpha’s current boilers and its most popular older ones. Some faults have simple steps you can do yourself. Others need a Gas Safe engineer.
One pattern is worth knowing by heart. If the A and B lights flash in turn, the system pressure is too low.
Topping up an Alpha boiler
Alpha’s own steps are short. First, find the filling loop under the boiler. It’s a braided metal hose with a tap at one or both ends. Open the tap or taps a quarter of a turn. You’ll hear water going in. Close them when the gauge is back in the green area, between 1 and 1.5 bar. The lights should then stop flashing.
If they still flash, add a little more water. Don’t go past the green area. If you overfill it, bleed a radiator to bring the pressure back down. Our guide on how to top up low boiler pressure has more detail.
No hot water?
Alpha suggests a few checks before you call anyone out:
- Has the power tripped? Check your fuse box.
- Is the boiler switched on, and is it showing a fault?
- Has the pressure dropped?
- Is the condensate pipe outside frozen?
Alpha also says to look for leaks around the boiler and pipes. A leak needs a Gas Safe engineer straight away.
Frozen condensate pipes
In very cold weather, the condensate pipe outside can freeze. Alpha says you can usually thaw it yourself with warm water. Our guide shows how to thaw a frozen condensate pipe. For new installs, Alpha sells a trace heating kit for the E-Tec range. It works with an outdoor sensor to keep the outside pipe from freezing.
Alpha gas boiler ranges
These are the gas boiler ranges on the Alpha website as of 21/10/2026.
- E-Tec Plus NX Combi
- E-Tec NX Combi
- Evoke NX Combi
- E-Tec NXS System
- E-Tec Regular Regular
Common Alpha fault codes
Codes can differ between models and ages of boiler. Always check the user manual for your exact model.
| Code | What it means | What you can do |
|---|---|---|
A and B lights flash in turn | The system pressure is too low. The gauge will usually read under 1 bar, outside the green area. | Top up with the filling loop until the needle is back in the green area, between 1 and 1.5 bar. |
Alpha manuals
Alpha puts its user guides and installation manuals on its own website. You can find Alpha manuals here. You'll need your model name. The GC number helps too. Our guide shows you how to find your boiler's model and GC number.
Stay safe. You can reset a boiler, top up its pressure and thaw a frozen condensate pipe yourself. Anything inside the case is a job for a Gas Safe registered engineer.
If you smell gas, leave the building and call 0800 111 999.