What counts as an HVAC or plumbing emergency after hours?

It's 11:40 on a Saturday night. One caller says their AC quit. Another says water is coming through the kitchen ceiling. A third says the basement "smells kind of like eggs." Whoever picks up has to decide right then who wakes your on-call tech, who gets a slot Monday, and who shouldn't be booked at all and needs to leave the house.

That could be you, your answering service, a tech who drew on-call this week, or an automated text-back. If the rules only live in your head, each of them will sort these calls differently. This post lays out a set of after-hours triage rules you can write down, adjust and hand to anyone who answers for you. It also shows how our missed-call text-back recipe applies them.

If you're a homeowner with a problem right now: if you smell gas, leave the building and call 911 or your gas utility once you're outside. If a carbon monoxide alarm goes off, get everyone outside to fresh air and call 911. Those calls come before calling a contractor. The rest of this post is written for the businesses that take these calls.

Why the rules need to be written down

After-hours calls are where judgment gets inconsistent. An answering service follows the script you gave it, word for word. A tech on call at 2 a.m. weighs the call against their own sleep. A text-back bot does whatever its rules and model say. If "no heat" means emergency to one of them and "Monday" to another, customers in the same situation get different service, and the one case that really matters can slip through.

Written rules also make the money conversation easier. If you charge an after-hours fee, the customer should hear which category they're in and why before anyone rolls a truck.

Four buckets, not two

Most scripts sort calls into "emergency" and "not emergency." We use four, because the first one isn't a service call at all.

1. Safety: send them to 911 or the utility, not to your schedule. Gas smell, carbon monoxide alarm, CO symptoms. Your job on this call is to get the person out and on the phone with the right people. Booking comes later, if at all.
2. Emergency: page on-call now. Damage is happening, or someone's health is at real risk, and it gets worse every hour.
3. Urgent: first thing tomorrow. The system is down, but nothing is getting worse overnight and nobody is at risk.
4. Routine: book it in normal hours. Estimates, maintenance, small drips, questions.

What goes in each bucket

These are our starting rules, not an industry standard. Where an outside source backs a rule, it's noted. The rest are business choices you should make yourself.

Situation	Bucket	Why
Gas smell, "rotten eggs", hissing at a gas line	Safety	Federal pipeline-safety guidance says leave the area and call 911 from well away from the leak (PHMSA)
CO alarm sounding, or headache/nausea/dizziness that might be CO	Safety	CPSC: move outside to fresh air, call 911, don't go back in until responders say so
Burst or split pipe, water running through a ceiling or across a floor	Emergency	Damage is ongoing; our choice
Sewage backing up into the house	Emergency	Health and damage; our choice
No water at all	Emergency	Our choice. Check your local water utility first: the outage may be theirs
No heat in freezing weather, or with an older adult, infant or sick person at home	Emergency	Older adults can get hypothermia in a home at 60–65°F (NIA); frozen pipes are a risk too (Red Cross)
No AC in extreme heat with someone at higher risk at home	Emergency (consider)	Older adults, children and people with chronic illness are at greater risk from extreme heat (Ready.gov)
No heat, AC or hot water in mild weather, nobody at risk	Urgent	System down, no damage happening
Slow drip, running toilet, noisy unit	Routine	Can wait for normal hours
Estimates, maintenance, "how much for…"	Routine	Not a breakdown

Two rows deserve a closer look.

Heat and cold depend on the weather and on who lives there. "No heat" in October in Phoenix and "no heat" in January in Minneapolis are different calls. The question to ask is "who's in the house, and how cold or hot is it inside?" not just "is the system down?" The National Institute on Aging says even mildly cool homes, 60 to 65°F, can lead to hypothermia in older adults, and recommends setting the heat to at least 68°F. The Red Cross says that if you're away in cold weather, you should leave the heat set no lower than 55°F to protect pipes. For heat, Ready.gov says older adults, children and people with some chronic conditions are at greater risk, and that fans create "a false sense of comfort" but don't lower body temperature.

"No water at all" might not be yours. A street-wide outage is the water utility's problem. Ask whether the neighbors have water before you send someone out.

What to say on a safety call, and what not to

The safety bucket is where a well-meaning answering service can do harm. Don't troubleshoot. Don't ask someone who smells gas to walk to the furnace and look at the pilot light.

Even official sources don't agree on the details. PHMSA's homeowner guidance tells people to make sure gas appliances are turned all the way off before they leave. New Hampshire's and Massachusetts' state guidance says not to try to shut off the gas, and Massachusetts and National Grid say not to open or close windows. All of them agree on the essentials: get out, don't use switches or anything that could spark, and call 911 or the gas utility from outside. That's why we keep our scripted message to that common core and let the utility or fire department give anything more specific:

Please leave the building now and call your gas utility's emergency line or 911 from outside. Don't use switches or flames. We're alerting our on-call tech too.

For a CO alarm, CPSC's guidance is just as short. Don't look for the source. Get outside to fresh air, call 911, count heads, and don't go back in until responders say it's safe. If the source turns out to be a furnace or water heater, that's when your service call starts.

It's fine to also alert your on-call tech. Some customers will want you there once the utility clears the house. But the first instruction always points them to the people who handle the emergency.

Five questions for whoever answers

Hand this to your answering service or on-call tech, in this order:

1. Do you smell gas, or is a CO alarm going off? If yes, give the safety script and stop.
2. Is water or sewage coming out right now? If yes, it's an emergency. Page on-call.
3. Who's in the house? Ask about older adults, infants or anyone sick.
4. How cold or hot is it inside? Combined with question 3, this decides whether no heat or no AC is an emergency or urgent.
5. Can it wait until we open? Tell them the next available time and any after-hours fee before you dispatch.

How our text-back applies these rules

Our missed-call text-back recipe texts after-hours callers and books a Jobber request from their replies. The after-hours greeting includes the gas-leak line before the customer even replies. When they do reply, a small AI model suggests an urgency. Then plain keyword rules check the customer's own words and can overrule the model:

• Safety words (gas smell, rotten egg, carbon monoxide, CO alarm) get the safety script above. On-call is paged and no booking is made. Test scenario S5 checks this.
• Emergency words (burst, flooding, ceiling leak, sewage backing up, no water at all, or no heat together with words like freezing, baby or elderly) mark the request emergency and page ONCALL_PHONE with the Jobber link (S4: a burst pipe at 2 a.m. on a Saturday).
• System-down words (no heat, no AC, no hot water) are marked at least urgent (S3: a no-cool call becomes an urgent Jobber request).

Where it's blunt:

• It doesn't know the weather. "No heat" is only treated as an emergency if the customer mentions cold or a vulnerable person. A customer who just types "furnace stopped working" on a freezing night gets urgent, not a page. No AC is never paged automatically. If you work somewhere with hard winters or extreme summers, edit the rule, or have the bot ask question 3 and question 4.
• Keyword lists miss wordings. "There's a weird smell from the stove" won't trip the gas rule. The greeting's gas warning is there partly for that reason.
• It's mock-tested. All 11 scenarios passed on October 27, 2026, against local mocks of Twilio and Jobber with a small local AI model. Nothing has run on a live phone line yet, so call your own number after hours and try a gas smell, a burst pipe and a no-heat call before you rely on it.

For how the build works step by step, see building the text-back in n8n and Twilio. For the costs and cheaper alternatives, see missed HVAC calls and text-back. The HVAC and plumbing hub has the rest of our recipes.

Sources

All checked October 27, 2026.

• U.S. Pipeline and Hazardous Materials Safety Administration, Recognizing and Responding to Pipeline Emergencies. Federal agency guidance.
• New Hampshire Department of Energy, What To Do If I Smell Gas; Mass.gov, What to do if you smell gas. State agency guidance.
• National Grid, Report a Gas Emergency. Gas utility guidance.
• U.S. Consumer Product Safety Commission, Carbon Monoxide Questions and Answers. Federal agency guidance.
• National Institute on Aging, Cold Weather Safety for Older Adults. Federal agency guidance.
• Ready.gov (FEMA), Extreme Heat. Federal agency guidance.
• American Red Cross, Preventing & Thawing Frozen Pipes. Nonprofit guidance.
• Our workflow and test log: missed-call text-back recipe. Mock-tested only.