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Mechanical Contractors Since 1919

General Info
Zien Service, Inc. is a single-source Mechanical Contractor offering a wide array of in-house services including Plumbing, Heating, Ventilation, Air-Conditioning, Refrigeration, Process Piping, Building Automation Systems and more. Since 1919, Zien has forged a solid reputation by providing excellent service throughout Wisconsin, Northern Illinois and Southern Minnesota. Our team is proficient in implementing solutions for commercial, industrial and institutional systems, regardless of size or complexity. Proof is demonstrated in our long list of prestigious projects. ​ With service offerings in the Consulting, Energy, and Facility Services fields, Zien advocates collaborative and sustainable solutions that are designed to ensure occupant comfort, improved system efficiency, reduce facility operational costs and optimize client profitability for the life of their building. Zien has the expertise to handle all your mechanical needs, from design and engineering to fabrication, installation, maintenance and repair. From restaurants and complex buildings to steel foundries and mission critical data centers, Zien services all brands of heating, air conditioning, ventilation and refrigeration equipment. Our Mission is to complete projects on time, within budget, and in a safe and cooperative work environment.
BBB Rating
BBB Rating and Accreditation information may be delayed up to a week.

Regular Hours

Extra Phones

Primary Phone: (414) 351-8700

Fax: (414) 351-8705

  • Water Heaters
Payment method
check, debit, visa, mastercard, amex, discover, all major credit cards
Serving Southeastern Wisconsin and Northern Illinois since 1919. Also special projects in the entire state of Wisconsin, Illinois and Minnesota.
Plumbing-Drain & Sewer Cleaning, Automation Systems & Equipment, Automation & Control System Engineers, Heating, Ventilating & Air Conditioning Engineers, Plumbers, Air Conditioning Contractors & Systems, General Contractors, Heating Contractors & Specialties, Sheet Metal Fabricators


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Jonathon G.



They cost me just under $1,000 in furnace repairs because they did not install the furnace correctly. I purchased a brand new Payne furnace from Zien. They assured this was a great furnace and very robust and dependable. After 1 year the furnace stopped working! They assessed the cause of the failure and it was caused from their incorrect installation. Guess what!?! Then they charged me to fix it! I had no choice but to pay them because it was zero degrees and I needed the furnace fixed ASAP. I tried to get them to cover the cost of repair after the fact and they not only did not oblige, their customer service rep (Chaz) was very disrespectful! I even sent a letter to the owner of the company and he refused to help. Zien has been around for a while and yet not accredited with the Better Business I know why. Stay away from this company for any needs! They do not stand by their products or service!

Robert S.



Have used Zien for several years however service mgr and tech have change and the service has too. 1 month after the spring AC check up the AC was not cooling and on one of the hottest days of the year and with a 1 year baby in the house the temp rose to the mid 80's. Humidity was equally high. Called Zien to see if the work that had just been done could be reworked so we might get AC. The Service Mgr said no and told me to get another service company to do the work. After hanging up I got a call from the tech and he was on his way. After an hour of work and another 200 bucks I thought the AC would work, it was ineffective all summer, but I was looking for another contractor. Mr Holland came out and while going thru the system a new system 4 yrs old, he found the manual stuff in the coils virtually blocking all air flow. Thanks Zien for what appears to be a rather poor decision about the use of the furnace manual.