Medium
31 on Alpha E-Tec S

Your boiler has lost its connection to your smart thermostat, meaning it cannot receive instructions on when to turn the heating or hot water on.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Loss of communication with external control (Alpha Climatic)

From this model's manual
Verified against the Alpha E Tec S installation & service manual, page 50.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check if your thermostat display is blank and replace its batteries if neededTurn the boiler off at the fused spur for 60 seconds and switch it back on to force a re-connectionEnsure the signal booster or receiver unit near the boiler is powered on and the status lights are active

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 31: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

32View →33View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →