At 02:10 on a January night, one caller gets the on-call engineer's mobile and four callers get a message in the morning diary. Most HVAC firms make that split from memory, differently each night, depending on who picked up. The split itself is not a matter of taste: parts of it are fixed by statute, and the rest already exists in writing, published by organisations that run far bigger repair operations than yours.
Start with the one call that is never triaged at all. A suspected gas escape or a sounding CO alarm goes to the National Gas Emergency Service on 0800 111 999, immediately, by whoever answers the phone. Nobody assesses it, nobody ranks it, nobody offers an engineer instead. Every gas network and government source gives the same instruction, and it is the first thing an answering script has to get right.
After that, the emergency, urgent and routine split you need is already drafted. Awaab's Law fixes a 24-hour investigate-and-make-safe duty for emergency hazards in social housing in England from 27 October 2025, and government guidance lists a broken boiler as an example. Housing associations publish their own three-tier matrices with hours and working days attached. Copy the shape.
What follows is the rule, in the order a firm meets it on a bad night, with the sources for each part and three widely-repeated numbers you should stop using.
- 01Winter volume is real. Here is the evidence.
- 02The call that is never triaged
- 03The taxonomy you do not have to invent
- 04Awaab's Law and the 24-hour clock
- 05From what the caller said to which tier
- 06What waking the engineer costs
- 07Commercial cooling runs on a different rule
- 08Three numbers to stop citing
- 09The rule, on one page
- 10FAQ and sources
- A suspected gas escape or CO alarm is a handoff, not a job. 0800 111 999, 24 hours a day. The answering line reads the safety steps and stops. No triage, no diagnosis, no booking.
- Loss of heating can be a statutory emergency. Under Awaab's Law, in force for social housing in England since 27 October 2025, an emergency hazard must be investigated and made safe within 24 hours of the landlord becoming aware, and government guidance gives a broken boiler as an example. For private lets, Landlord and Tenant Act 1985 s.11 requires repair in a reasonable time with no fixed number attached.
- Three tiers, already published. Trust Housing Association works to a 4-hour emergency make-safe, 3 working days urgent, 20 working days routine. Fife and Livv publish comparable tiers. That is the matrix to copy, in your own words.
- Waking the engineer is a pay event and a rest event. Under Royal Mencap Society v Tomlinson-Blake [2021] UKSC 8 a sleeping on-call worker is paid the minimum wage only for time awake and working, while Matzak shows that tightly constrained standby can count as working time for rest and the 48-hour limit. The triage rule controls both.
- Two claims you will see everywhere have no primary source. Boiler breakdowns concentrated in the first cold week, and the missed-call and voicemail percentages. We looked. Neither has a statutory, regulatory or peer-reviewed origin, so neither appears here as fact.
Winter volume is real. Here is the evidence.
The seasonal case for out-of-hours cover is easy to make badly, with a vendor statistic. It is also easy to make properly, because UK gas demand is measured daily and published.
Local Distribution Zone demand, which is the residential and commercial gas that heats buildings, swings by a factor of four to five between the August trough and the January peak. Inside winter it swings again, day to day, as cold fronts arrive. Those are the two facts that justify staffing a night line in December and not in July.
Endpoints only. These are the trough and peak values published on each basis, not a modelled monthly series, and the two bases are not directly comparable to each other. The third row measures something different again: day-to-day volatility within the cold period, which is the shape that actually fills an out-of-hours line. Figures compiled in OIES paper NG201 (October 2025) and attributed there to the National Gas Transmission Data Portal and DESNZ Energy Trends section 4.
Weather alerting gives the second signal, and it arrives with notice. UKHSA runs the Weather-Health Alerting system with the Met Office, colour-coded on impact with a matrix score. An amber cold-health alert means cold weather impacts are likely to be felt across the whole health service
, with the whole population potentially at risk. Recent seasons carried amber alerts across English regions to 12 January 2024 and in Kent to 8 January 2025, and yellow alerts in the South East in February and November 2025. If you want a trigger for standing up extra cover, that dashboard is a better one than a feeling about the weather.
What the alerts are for: UKHSA's alerts exist for health protection, not for trade demand planning. Treat them as an early warning that your phone is about to be busy, which is a use they support, rather than as a measure of breakdown volume, which they do not measure.
The call that is never triaged
Everything else in this post is a judgement your firm makes and writes down. This one is not. On a suspected gas escape or a sounding CO alarm, the answering line hands the caller to the National Gas Emergency Service and reads the safety steps. Northern Gas Networks states that networks aim to attend uncontrolled escapes within one hour and controlled escapes within two.
Getting this into the first fifteen seconds of the call has a second benefit. It also removes the worst failure mode of any answering system, human or automated: a caller who describes a gas smell while an agent works through a booking flow.
"I can smell gas."
"The carbon monoxide alarm is going off."
"We've all got headaches and we feel sick."
"Someone hit a pipe in the garden."
- Call it now, from outside if you can
- Open doors and windows
- Turn off at the emergency control valve if it is safe to reach
- No naked flames, do not smoke
- Do not touch electrical switches
- For a CO alarm: get everyone out, do not go back in until you are told it is clear
- If anyone is unwell, NHS 111, or 999 if it is serious
The engineer-facing equivalent of this rule is the Gas Industry Unsafe Situations Procedure, published as IGEM/G/11 and reproduced by Gas Safe Register as Technical Bulletin 001. It classifies an installation as Immediately Dangerous or At Risk. Since June 2024 the consumer message for both is the same: "Danger, Do Not Use." The Not to Current Standards category left the unsafe-situations warning process in 2016. Where a customer refuses permission to disconnect a natural gas installation, the engineer reports it to the Gas Emergency Service Provider, which has legal powers to demand entry or disconnect.
The taxonomy you do not have to invent
Firms tend to write their out-of-hours rule from scratch, usually in an argument at the end of a busy week. Social landlords settled this years ago and publish the result, because their tenants need to know what to expect. The tiers, the hours and the working days are all in the open.
| Provider | Emergency | Urgent | Routine |
|---|---|---|---|
| Trust Housing AssociationScotland | 4 hours target to attend and make safe | 3 working days | 20 working days |
| Fife Housing Grouprepairs policy PDF | 4 hours to respond and make safe. Out-of-hours call centre logs details and contacts the relevant colleague | 3 days | not stated |
| Livv Housing Grouprepairs policy 2024 to 2027 | Reportable 24/7/365. Make safe by isolating water, gas or electricity | not stated | 28 days |
| Clarion Housinglargest UK housing association | Out-of-hours service covering emergencies | not stated | not stated |
Three things to take from this. The top tier promises to make safe, not to fix, which is the only promise an on-call engineer can keep at 3am. Every provider names a route for out-of-hours reports and says what the receiving line does with them. And the tiers are defined by the effect on the occupant rather than by the part that failed, which is what makes them usable by whoever answers the phone.
Awaab's Law and the 24-hour clock
If you hold any social housing contracts, or subcontract to a provider that does, one of your customer's duties has a number attached to it. The Hazards in Social Housing (Prescribed Requirements) (England) Regulations 2025, made under the Social Housing (Regulation) Act 2023, imply repair duties into social tenancies. Phase 1 has been in force since 27 October 2025.
The triage test in the government guidance is phrased as a question a manager can actually answer: would a reasonable landlord make this hazard safe in 24 hours, or in 15 working days? Read the duty alongside it and the 15 working days resolves into two steps, 10 plus 5.
Investigate and complete relevant safety work within 24 hours of becoming aware. The clock starts on awareness, not on a work order. Government and local-authority guidance lists gas leaks, a broken boiler, total loss of water supply, dangerous electrical faults and significant leaks as examples.
Scope matters. Awaab's Law applies to social housing in England. Private lets run on Landlord and Tenant Act 1985 s.11, which requires installations for space heating and heating water to be kept in repair and proper working order and repairs done in a reasonable time. Shelter's summary is direct: under section 11 there are no strict timescales that landlords must follow. Extension to the private rented sector via the Renters' Rights Act 2025 has no confirmed implementation date.
From what the caller said to which tier
A tier definition only works if it can be applied by whoever is holding the phone, from what the caller actually says, without a diagnosis. That means writing the rule against symptoms and occupants rather than against components. "No heat, tenanted, infant in the property" is answerable at 2am. "Failed diverter valve" is not, because nobody knows that yet.
- Tell the caller whether the appliance is safe to use
- Name a likely fault or a likely cost
- Promise an attendance time the firm has not authorised
- Talk a caller through anything on a gas appliance
- Decide that a vulnerability does not count
- Rank one caller against another on its own judgement
The vulnerability question is the one to settle in advance and in writing: which stated circumstances lift a call a tier, and what the line records. Deciding that at 2am, on the phone, is how two identical calls get two different answers.
One point of order on the landlord check, since it comes up on the same phone line. Under regulation 36 a landlord must have each relevant gas appliance and flue safety-checked within 12 months of installation and at intervals of no more than 12 months, keep the record until two further checks have been done, give it to existing tenants within 28 days and to new tenants before they move in. Regulation 36A, added in 2018, allows the check up to two months early while keeping the original expiry date. It is a diary problem, not a night problem, and it should never compete with a tier 1 call.
What waking the engineer costs
The reason to write the rule down is not tidiness. Every genuine call-out has two costs that land in different places, and both are governed by law rather than by your rota spreadsheet.
The Supreme Court held, per Lady Arden, that if the worker is permitted to sleep during the shift and is only required to respond to emergencies, the hours in question are not included in the NMW calculation for time work or salaried hours work unless the worker is awake for the purpose of working.
Royal Mencap Society v Tomlinson-Blake [2021] UKSC 8, 19 March 2021
In Ville de Nivelles v Matzak a retained firefighter who had to stay contactable and reach the station within 8 minutes was on working time throughout standby, because the constraints objectively and significantly limited his ability to pursue personal and social interests. In the 2021 Radiotelevizija Slovenija and Stadt Offenbach cases the CJEU clarified that being contactable with a longer return window, around an hour, does not automatically count.
CJEU C-518/15 (2018) · C-344/19 and C-580/19 (2021)
Two consequences for the rota. A call-out breaks the 11 consecutive hours of daily rest in WTR 1998 reg 10, which raises compensatory rest and the 48-hour average. And the tighter the response window you impose on standby, the closer the whole standby period comes to counting as working time. A triage rule that wakes the engineer only for tier 1 is therefore a labour-cost and welfare control as much as a customer service policy.
Post-Brexit, UK tribunals may still have regard to that CJEU case law. Take your own advice on how your standby terms sit against it, because the answer depends on your response window, your obligation to attend and your geography, none of which are in this post.
Commercial cooling runs on a different rule
Firms that cover both sides of the trade often run one out-of-hours rule for everything. A refrigerant fault does not behave like a domestic gas escape, and treating them alike sends engineers out for the wrong reasons.
Only F-gas certified engineers may handle refrigerant, and venting is illegal. Enforcement sits with the Environment Agency in England and its equivalents elsewhere. Northern Ireland follows the updated EU Regulation 2024/573 under the Windsor Framework, so a firm working both sides of the Irish Sea is working to two regimes. The practical read for a night line: a commercial cooling fault is scheduled, certificated and record-kept work, so the out-of-hours question is usually about the load in the room rather than about life safety. A server room, a pharmacy fridge or a food store can still be a genuine tier 1, on your own definition rather than on a statutory one.
Three numbers to stop citing
All three appear in supplier material for this exact product category, including from our competitors. We went looking for the primary sources. Here is what is there.
"Boiler breakdowns spike in the first cold week of the season."
Plausible, and possibly true. No Gas Safe Register, HSE, Ofgem or ombudsman dataset quantifies boiler-breakdown or heating-failure incidence by cold snap or by heating-season start. The claim lives in vendor pages and trade magazines that cite each other. The demand seasonality in Fig. 1 is real and published; breakdown incidence by season is not, so we do not assert it. If Gas Safe or DESNZ ever publishes it, this section gets rewritten.
"X% of callers never leave a voicemail." "62% of plumbing emergencies happen after hours."
No Ofcom Communications Market Report, ONS release or peer-reviewed study we could find produces these figures. They circulate among answering-service and AI-receptionist marketing pages, and at least one vendor describes its own number as the widely cited industry figure, which is a description of circulation rather than of evidence. Our earlier post on the cost of missed calls traces two of the most-quoted examples to a dead link and a 2016 study of 85 businesses.
"Winter electricity demand is 36% higher than summer."
That figure is from a DECC special feature in Energy Trends, March 2014, and compares one winter day, 12 December 2012, with one summer day, 23 July 2013. It is more than a decade old and rests on a two-day comparison. Newer NESO figures give a winter average-cold-spell peak near 60 GW against a 2025 summer peak of 29.7 GW, and DUKES 2025 chapter 5 records an actual winter peak of 51.5 GW, up 8.8% on 2024. Those sit on different measurement bases and were never published as a ratio, so quoting them as one would be inventing a statistic.
The rule, on one page
Write it before you automate anything, because an answering service of any kind, human or AI, will simply execute whatever ambiguity you hand it. Seven lines is enough. Line one is not yours to change.
-
The handoff. fixedSuspected gas escape or CO alarm: caller directed to 0800 111 999 immediately, safety steps read from script, no job created, no attendance offered. Recorded as a handoff, not a call-out.
-
Your three tiers, defined by effect on the occupant and written in the words a caller would use.Tier 1: no heating or hot water with a stated vulnerability, uncontained water, an appliance the customer has been told not to use. Tier 2: intermittent heat, pressure loss, a fault with heat still available. Tier 3: everything else.
-
What each tier is promised, in hours or working days, and what the promise is for.Tier 1: attend and make safe within 4 hours. Tier 2: booked next working day, attended within 3 working days. Tier 3: within 20 working days. Make safe, not fix.
-
Which stated circumstances lift a call one tier, and how they are recorded.Infant under 12 months, occupant over 75, disability or medical equipment in use, a social tenancy with a 24-hour statutory duty. Recorded verbatim in the caller's own words, never judged on the call.
-
Who is on call, how they are reached, and what happens on no answer.Named engineer per night on a published rota. Two attempts, three minutes apart, then the second name, then the duty director. Every attempt logged with a timestamp.
-
What the answering line may never say.No safety verdict, no diagnosis, no price, no unauthorised attendance time, no talking a caller through work on a gas appliance.
-
What lands in the morning, and in what format.Caller's words verbatim, address, tier applied, the rule that applied it, vulnerability noted, time of report, who was contacted and when, and what the caller was told to expect.
The last line is what makes the rule reviewable. A month of logged decisions shows whether the tier definitions match the calls you actually get, and it is the record you need if a customer, a landlord or a regulator ever asks why one call got an engineer at 2am and another did not.
Two of those lines are also the questions worth putting to any answering supplier in writing. Can the tiers be defined in our words, and can the line be made to refuse things? A demo settles neither.
Can the gas and CO handoff be made to run before anything else?
It should be the first question on the call and it should end the call flow. Ask to hear it on a test number, not to see it on a slide.
Are the tier definitions ours, in our words, and editable by us?
A supplier's built-in severity model is someone else's judgement applied to your rota and your engineers' rest.
What does the line refuse to do, verbatim?
Ask for the refusal script. It should decline diagnosis, decline prices and decline attendance times, and offer a human without being asked twice.
What exactly is written down, and can we get the caller's own words?
A paraphrase is no use in a complaint. Line 7 of the rule needs verbatim capture and a timestamp on the report, not a tidy summary.
What this post does not do
It does not tell you whether a given call is an emergency hazard, whether your standby terms make the whole shift working time, or what your firm owes a particular tenant. Those turn on facts and contracts we do not have. Awaab's Law applies to social housing in England only; the Gas Safety (Installation and Use) Regulations apply across Great Britain; F-gas differs between GB and Northern Ireland. This is not legal advice, and the on-call and working-time points in particular are areas where a firm should take its own. What it does is quote the instruments and link each one, so an owner can read them in an evening and write the rule the following morning.
FAQ
Is a broken boiler an emergency repair?
In social housing in England it can be. Government and local-authority guidance supporting Awaab's Law gives a broken boiler as an example of an emergency hazard, which carries a duty to investigate and complete relevant safety work within 24 hours of the landlord becoming aware. In the private rented sector there is no fixed statutory number: Landlord and Tenant Act 1985 s.11 requires repair in a reasonable time. Published housing-provider tiers treat total loss of heating as their top tier, usually with a 4-hour make-safe target.
Who should a caller ring if they smell gas?
The National Gas Emergency Service on 0800 111 999, which runs 24 hours a day. Official advice from National Gas, Cadent, SGN and Northern Gas Networks is to call immediately, open doors and windows, turn off at the emergency control valve if it is safe to reach, avoid naked flames and not touch electrical switches. An answering line, human or automated, hands the call over. It does not triage it.
What should happen when a carbon monoxide alarm goes off?
UKHSA and NHS guidance: stop using all appliances, get everyone out, ventilate, and call 0800 111 999 or the HSE Gas Safety Advice Line on 0800 300 363. Do not go back in until you are told it is clear, and call NHS 111, or 999 if someone is seriously unwell.
How quickly must a landlord fix a heating failure?
It depends on the tenancy. For a social tenancy in England, an emergency hazard carries the 24-hour investigate-and-make-safe duty under Awaab's Law, and a significant hazard runs on a 10 working day investigation, a written summary within 3 working days of that concluding and safety work within 5 working days. For a private tenancy, s.11 of the Landlord and Tenant Act 1985 requires a reasonable time, and Shelter notes there are no strict statutory timescales.
Do you have to pay an engineer for being on call?
For minimum wage purposes, a worker permitted to sleep and required only to respond to emergencies is not treated as working unless awake for the purpose of working: Royal Mencap Society v Tomlinson-Blake [2021] UKSC 8. Whether the standby period counts as working time for rest breaks and the 48-hour average is a separate question, and the CJEU case law turns on how tightly the worker is constrained. Contractual standby payments are a matter for the employment contract.
How does an answering service decide what counts as an emergency?
It should not decide. It should apply definitions you wrote, from what the caller stated, and escalate anything it cannot place. That is why Fig. 5 maps caller phrases to tiers rather than mapping faults to tiers: whoever answers the phone has the caller's words and nothing else.
Is out-of-hours demand really higher in winter?
Heating demand is, and it is measured. Local Distribution Zone gas demand swings roughly four to five times between the August trough and the January peak on published National Gas and DESNZ figures, and inside the cold period it can move from about 120 to about 280 MMcm/d within ten days. There is no primary UK dataset on boiler-breakdown incidence by season, so the honest claim covers heating load and weather alerts. Breakdown counts are not measured.
Where that leaves a decision
The rule comes first, and it is a morning's work. Once it exists, the question of who executes it at 2am becomes a straightforward operational choice between a rota that answers its own phone, an answering service, and an AI agent that reads your tiers back to the caller. Any of the three can run a good rule. None of them can rescue an ambiguous one.
Magixis builds the AI receptionist for HVAC firms described here, and for plumbers and heating engineers. It applies your tiers, in your words, and hands a suspected gas escape straight to 0800 111 999. That is why this post is about reg 36 and the Awaab's Law clock rather than about never missing a call.
- National Gas, emergency contacts
- Cadent, gas emergencies
- SGN, smell gas
- Gas Safe Register, GIUSP explained, 22 Apr 2024
- IGEM/G/11, Gas Industry Unsafe Situations Procedure
- UKHSA, carbon monoxide general information
- NHS, carbon monoxide poisoning
- GSIUR 1998, reg 36
- HSE, landlords' duties FAQ
- HSE INDG285, a guide to landlords' duties
- GOV.UK, Awaab's Law, triaging hazards
- GOV.UK, Awaab's Law Phase 2 guidance
- Landlord and Tenant Act 1985, s.11
- Homes (Fitness for Human Habitation) Act 2018
- Trust Housing Association, repair priorities
- Fife Housing Group, repairs policy
- Livv Housing Group, repairs policy 2024 to 2027
- Clarion Housing, responsive repairs policy
- Four Million Homes, emergency repairs and priorities
- Working Time Regulations 1998
- Royal Mencap Society v Tomlinson-Blake [2021] UKSC 8
- CJEU C-518/15, Ville de Nivelles v Matzak
- OIES NG201, UK gas demand volatility, Oct 2025
- National Gas Transmission Data Portal
- DESNZ, Energy Trends, gas
- Met Office, Heating Degree Days
- Met Office, Cooling Degree Days
- UKHSA, weather-health alerts
- UKHSA, weather-health alerting user guide
- DECC, seasonal variations in electricity demand, Mar 2014
- DUKES 2025, chapter 5
- Fluorinated Greenhouse Gases Regulations 2015
- POST-PN-0752, winter mortality