The HVAC emails worth sending to your own customers are tied to a date or a job: a tune-up reminder before the season starts, a follow-up on an estimate nobody answered, a review request the morning after a visit, and a maintenance plan offer to people who only call when something breaks. Below are six templates to paste into Gmail today, when to send each one, and how to keep the list clean so the mail lands in the inbox. These are emails to homeowners and customers you have already served. If you want to win property managers and building owners as new accounts, that is a different job, covered in cold email templates for plumbers and HVAC companies.
Start with the list, not the template
A reminder email only works if it knows something about the person. Pull five columns out of your invoices into a sheet: name, email, address, the equipment you installed or serviced, and the date of your last visit. That is enough to write "your system was installed in 2019" or "we last saw your furnace in October of last year" in the first line, and that one sentence is the difference between a reminder and a flyer.
Say a company called Northfield Comfort has 640 past customers in its invoicing tool. About 400 have an email address. Of those, maybe 150 have not had a tune-up in over a year. That group of 150 gets the first email, and the other 250 get the emails that fit where they are. Your numbers will differ, but the sorting is the same: group people by what happened last, then write to the group.
Template 1: the spring tune-up reminder
Subject: your AC before the first hot week
Hi Marcy,
We installed your cooling system in June of 2019, and the last time we looked at it was last spring. Before the first stretch of 90-degree days, this is the easiest time to book a tune-up, because the schedule is open and a small problem costs less to fix now than on a Saturday in July.
The visit takes about [visit length] and costs [your price]. Reply with two times that work and I will hold one, or call [phone].
Dana, Northfield Comfort, [mailing address]
If you would rather not get these, reply "stop" and I will take you off.
When to send it: four to six weeks before the first hot week where you work. In Phoenix that is March, in Minneapolis it is May. Why it works: it states the date of your own last visit, gives a reason to book now instead of later, and asks for one thing. If you want to follow up, wait seven days and send two sentences: "Still have a few spots before the heat. Want me to hold one for you?"
Template 2: the fall heating check
Subject: your furnace before the first cold snap
Hi Marcy,
A quick note before heating season. Your furnace is [age] years old, and the fall visit is where we [what your visit includes: check the burner, test the safety controls, replace the filter, and so on].
It is [your price] and takes about [visit length]. Which day next week works?
Dana
Keep this one even shorter than the spring email, because by October people already know they need heat. Put the checklist in your own words. A homeowner reads "we test the safety controls" as a reason to book, and "comprehensive system diagnostic" as an advertisement.
Template 3: following up on an open estimate
Subject: your estimate for the new system
Hi Marcy,
Checking in on the estimate I sent on [date] for the replacement system. The decision is yours to make on your own schedule. One thing worth knowing: [one real fact, for example, our install calendar is open the week of the 14th, or the price holds until the 30th].
Is there anything in the estimate you want me to explain or change? I can also rework it with a different system if the price was the sticking point.
Dana
Send it three days after the estimate and again at ten days. The question at the end invites an objection, which is what you want, because a customer who says "the price was high" is still in the conversation. A customer who says nothing has already decided. There is more on timing and wording in estimate follow-up for contractors.
Template 4: the review request
Subject: how did we do today?
Hi Marcy,
Thanks for having us out this morning. If the visit went well, a short Google review helps other homeowners find a tech they can trust. Here is the link: [your Google review link]. If something was not right, hit reply and tell me directly, and I will call you today.
Dana
Send it the next morning, not the same afternoon, so the work has a chance to prove itself. Ask every customer, not only the ones you think were happy. Google's policy says not to selectively ask for positive reviews, and a steady stream from everyone looks more real than a wall of five-star posts all dated the same week. The review routine is covered step by step in how to get more Google reviews.
Template 5: the maintenance plan offer
Subject: skip the tune-up reminders for good
Hi Marcy,
Most customers call us when something breaks. A maintenance plan flips that: two visits a year, priority booking when it is 100 degrees out, and [your repair discount] on any repair. It is [price] a year, and we put your visits on the calendar so you never have to remember.
Want me to sign you up? I will set both visits for dates you pick.
Dana
Send this two weeks after a repair or install, to people who called once and never booked a tune-up. Before you offer a plan, work out what it costs you to run. Two visits is two hours of tech time plus drive time, and the price has to cover that with room left over. Do the math with your own labor rate. If the numbers do not work at the price a homeowner will accept, fix the plan first.
Template 6: the 30-day check-in after an install
Subject: how is the new system running?
Hi Marcy,
It has been about a month since we installed your new system. Is it holding the temperature you expected, and is anything making a noise it should not? If yes, reply and I will send someone.
One housekeeping item: [if your manufacturer asks for warranty registration within a set window, say so here and include the link].
Dana
Many manufacturers want a new system registered within a window after installation to get the full warranty period, so check the terms for the brands you install. This email helps the customer, catches a problem before it becomes a complaint, and reminds them you exist for the next time someone they know needs a system.
Subject lines that fit HVAC
- your AC before the first hot week
- your furnace before the first cold snap
- about the estimate for [street name]
- how did we do today?
- two tune-ups a year, one phone call
- how is the new system running?
- filter change time
- still have spots before the heat
How many to send, and from where
A regular Gmail account can send to about 500 recipients a day, and a paid Google Workspace account allows 2,000 messages a day. You will not hit that with one email to 150 people, but a full 640-person list in one sitting can trip other filters. Send 50 to 100 a day over a week. If you do hit a wall, Gmail daily user sending limit exceeded explains how to resume.
Send each email from your own name and address, not a "no-reply" box. People answer a person. The replies are also the point: a homeowner who writes back "yes, Thursday" is a booked job.
Keep the list clean
Remove an address after one hard bounce. Take anyone off who replies "stop," the same day. Put your mailing address in the signature and keep the opt-out as a plain line, as in the first template, because US email law covers commercial messages to existing customers too, not only strangers. For the basics, see is cold email legal. And skip the discount in every message. A promotion each month teaches customers to wait for the next one.
Past customers are the easiest list to start with, and the part that slips is the follow-up. Rocketship's workers can write to each one from your own Gmail, follow up until they answer, and stop the moment someone replies. You can try it on your own customer list with a 7-day free trial, card required.