Siefert Mechanical

Siefert Mechanical Providing both light commercial & residential service in St. Louis!

Specializing in new system installs, System replacement, indoor air quality products such as humidifiers, EAC electronic air cleaners, ductless systems (mini splits) & Wi-fi thermostats.

This is a 25-year-old Goodman Unit I installed that is still purring like a kitten. I think maybe we put a couple of cap...
03/31/2026

This is a 25-year-old Goodman Unit I installed that is still purring like a kitten. I think maybe we put a couple of capacitors in it in those years that’s it

03/31/2026
Another one bites the dust! Call for a free quote 314.598.1658
03/31/2026

Another one bites the dust! Call for a free quote 314.598.1658

Before and after, give us a call for a free quote 314-598-1658 thank you
03/21/2026

Before and after, give us a call for a free quote 314-598-1658 thank you

New AC system call for a free quote 314-598-1658
03/11/2026

New AC system call for a free quote 314-598-1658

Couple of installs we just wrapped up give us a call for a free quote 314-598-1658
02/27/2026

Couple of installs we just wrapped up give us a call for a free quote 314-598-1658

Couple of installs we did this week. Call for a quote 314.598.1658
02/06/2026

Couple of installs we did this week. Call for a quote 314.598.1658

Building a house? We can help with your HVAC needs, call for a free quote 314-598-1658.
01/30/2026

Building a house? We can help with your HVAC needs, call for a free quote 314-598-1658.

12/25/2025

Happy Holidays from the Siefert Mechanical family to yours! Everyone stay safe and have a wonderful holiday🎄

Happy Thanksgiving from our family to yours!!! We are thankful for everyone supporting our business and wish you all a b...
11/27/2025

Happy Thanksgiving from our family to yours!!! We are thankful for everyone supporting our business and wish you all a blessed day!!

Photo dump, it's been BUSY BUSY BUSY. Here are some of this Summer's installations!! Call for a free quote! 314.598....
09/23/2025

Photo dump, it's been BUSY BUSY BUSY. Here are some of this Summer's installations!! Call for a free quote! 314.598.1658

Address

O'Fallon, MO
63366

Opening Hours

Monday 8am - 4:30pm
Tuesday 8am - 4:30pm
Wednesday 8am - 4:30pm
Thursday 8am - 4:30pm
Friday 8am - 4:30pm

Telephone

+13145981658

Website

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