*The Angi rating for Central Vacuum Installation companies in Hayden, AZ is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Central Vacuum Installation needs.
*The HomeAdvisor rating for Central Vacuum Installation companies in Hayden, AZ is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Central Vacuum Installation needs.
Last update on April 24, 2025
D&H Heating and Air Conditioning is Tucson's leading HVAC Company and has been providing Tucson with furnace and AC repair, maintenance and new installation services since 1959. D&H is dedicated to your climate-control solutions and your family's indoor comfort. We are your heating furnace and AC specialists in Tucson and Southern Arizona. All of our HVAC heater and air conditioning repair technicians are committed to customer service of the highest quality. A D&H technician will always strive to serve you with courtesy and respect. Our technicians are all certified with the Seal of Safety, demonstrating our level of professionalism, and are NATE-certified, guaranteeing that they are well trained and skilled. D&H Air Conditioning is one of the leading providers of air conditioner repair, air conditioning service, new AC systems, furnace repair and heating system repair in Tucson, delivering rapid response for broken heaters and air conditioners. Our certified HVAC technicians will quickly respond to your needs whether you need emergency air-conditioning repair, have heating problems or need a new system installation. At D&H, we are dedicated to your satisfaction and committed to providing the highest quality of products and service to your family. We believe it is our duty to invest in the extra training, equipment, and most qualified technicians to ensure the comfort and protection of your family and your home.
"The most trustworthy, reliable and competent outfit. They kept me appraised at all steps of the repair. Highly professional. They replaced the Freon, coil and filter. It was under warranty, I purchased the a/c from them 11 or 12 years ago and it was still under warranty so I only paid for the Freon. My home warranty under American Home Shield quoted me just under $2000 so this was a no brained. I am a confident D and H client and will continue to rely on their expertise, professionalism and compassionate service. Parts had to be ordered so I was without a/c during the 110 degree heatwave. No worries! D and H brought me at no charge a large portable A/C unit so we managed just fine. I highly recommend D and H!"
katherine c on June 2024
D&H Heating and Air Conditioning is Tucson's leading HVAC Company and has been providing Tucson with furnace and AC repair, maintenance and new installation services since 1959. D&H is dedicated to your climate-control solutions and your family's indoor comfort. We are your heating furnace and AC specialists in Tucson and Southern Arizona. All of our HVAC heater and air conditioning repair technicians are committed to customer service of the highest quality. A D&H technician will always strive to serve you with courtesy and respect. Our technicians are all certified with the Seal of Safety, demonstrating our level of professionalism, and are NATE-certified, guaranteeing that they are well trained and skilled. D&H Air Conditioning is one of the leading providers of air conditioner repair, air conditioning service, new AC systems, furnace repair and heating system repair in Tucson, delivering rapid response for broken heaters and air conditioners. Our certified HVAC technicians will quickly respond to your needs whether you need emergency air-conditioning repair, have heating problems or need a new system installation. At D&H, we are dedicated to your satisfaction and committed to providing the highest quality of products and service to your family. We believe it is our duty to invest in the extra training, equipment, and most qualified technicians to ensure the comfort and protection of your family and your home.
"The most trustworthy, reliable and competent outfit. They kept me appraised at all steps of the repair. Highly professional. They replaced the Freon, coil and filter. It was under warranty, I purchased the a/c from them 11 or 12 years ago and it was still under warranty so I only paid for the Freon. My home warranty under American Home Shield quoted me just under $2000 so this was a no brained. I am a confident D and H client and will continue to rely on their expertise, professionalism and compassionate service. Parts had to be ordered so I was without a/c during the 110 degree heatwave. No worries! D and H brought me at no charge a large portable A/C unit so we managed just fine. I highly recommend D and H!"
katherine c on June 2024
Central Valley Mechanical Services is a full-service mechanical contracting firm specializing in commercial and industrial heating, ventilation, air conditioning, and refrigeration. Established in 2021, Central Valley Mechanical Services remarkable growth and solid reputation reflect the company’s commitment to quality, safety, training and customer satisfaction. Our company specializes in proactive maintenance, service, and installation of heating, ventilation, air conditioning (HVAC), and refrigeration equipment for a diverse customer base that focuses in the commercial service and manufacturing industries. Our reputation for supplying quality design, products, installations, and service is our Company’s biggest asset. We are very proud of the people on our team, the customer relationships we have established and the progress our company continues to make as we strive to deliver more value to our customers.
Central Valley Mechanical Services is a full-service mechanical contracting firm specializing in commercial and industrial heating, ventilation, air conditioning, and refrigeration. Established in 2021, Central Valley Mechanical Services remarkable growth and solid reputation reflect the company’s commitment to quality, safety, training and customer satisfaction. Our company specializes in proactive maintenance, service, and installation of heating, ventilation, air conditioning (HVAC), and refrigeration equipment for a diverse customer base that focuses in the commercial service and manufacturing industries. Our reputation for supplying quality design, products, installations, and service is our Company’s biggest asset. We are very proud of the people on our team, the customer relationships we have established and the progress our company continues to make as we strive to deliver more value to our customers.
Im a well rounded in all type of construction and household maintenance with heating and cooling installations and maintenance ac equipment Im a hard work and very friendly and do the work as if you were my own family I make sure everyone has a wonderful experience with any work I do and always get get reviews when work is done
Im a well rounded in all type of construction and household maintenance with heating and cooling installations and maintenance ac equipment Im a hard work and very friendly and do the work as if you were my own family I make sure everyone has a wonderful experience with any work I do and always get get reviews when work is done
We have been proudly servicing residential customers in the East Valley since 2007. And now we are excited to offer Concrete Driveway and Masonry services!! We believe in showing up on time and getting the job done right the first time. A majority of our team have from ten to 30+ years of experience. Contact us for a FREE consultation and give us a chance to surpass your vision and expectations.
"From start to finish working with Louis and his team was great. The finished product looks great, and we have no complaints. The individuals who tore off the old roof and installed the new metal roof were on time and went straight to work, kept everything picked up and clean at the end of each day. anytime i had questions Louis was available to answer them in a professional manner. I would highly recommend them for roof replacement."
Mike J on October 2024
We have been proudly servicing residential customers in the East Valley since 2007. And now we are excited to offer Concrete Driveway and Masonry services!! We believe in showing up on time and getting the job done right the first time. A majority of our team have from ten to 30+ years of experience. Contact us for a FREE consultation and give us a chance to surpass your vision and expectations.
"From start to finish working with Louis and his team was great. The finished product looks great, and we have no complaints. The individuals who tore off the old roof and installed the new metal roof were on time and went straight to work, kept everything picked up and clean at the end of each day. anytime i had questions Louis was available to answer them in a professional manner. I would highly recommend them for roof replacement."
Mike J on October 2024
If you are having any troubles with cooling or heating your house please feel free to call. We are available 24 hours a day. There is no job too big or too small.
If you are having any troubles with cooling or heating your house please feel free to call. We are available 24 hours a day. There is no job too big or too small.
We are an up and coming Home Remodeling company specializing in HVAC, Replacement Windows, Baths, and so much more. I welcome you to send an email or give us a call anytime. We are very flexible with scheduling and have installers and salesman with over 25 years of experiencing.
"We had accidentally broken a window while doing some remodeling in our kitchen and called RemodAz and a couple other window companies for competitive bids. We ended up signing a contract in October 2020 as we were told by the sales guy they would only take 6-8 weeks to get the job done, and they could do it faster than the others, because if we order now he can get the windows in as part of a large order for a local builder. At the end of December – with no communication other than me constantly inquiring where my windows are, they said they are having sourcing issues due to covid and could not give me an update, but could get me more information the next week after a call with the manufacturer, which I still didn’t get a call and was told it was my fault for not understanding that “next week” isn’t “next week” – it was the week after next week. Since we were adding a large sliding door and we had tile removed, we could not finish flooring until the door was in, so we had to keep deferring that install because we couldn’t get RemodAz to commit. Finally, towards the end of January they were out to install and man what a mess that was. Replacing 5 windows in the kitchen with two side windows and a plate glass window; replacing a window and a sliding glass door with a double slider; and then two windows in the front of the house. All with all aluminum frames, new windows and doors which is great because this matches the rest of the house. The door installation required a new header and some wire re-routing, and they wanted to just tie new wires with the old in the wall cavity which is not legal. I made them put a junction box in and I don’t think the way they crammed 8 wires into a double gang box was legal either but oh well. The new header goes in, and the opening is incorrectly sized for the door and it’s also sticking out a full inch on the left side into the room. 1 inch past the interior drywall and it’s clearly at an angle. They called a drywall guy out to patch the walls and he just laughed and left. They end up shaving the header down and just crumpled up some insulation and stuffed it in holes vs actually putting it into the wall cavity completely. I ended up redoing the insulation myself, oh and also had to supply the insulation and most of the wood myself along with quite a few tools. They ended up having an electrician come out to wire the new switches, and this was before the drywall went on, so the next set of drywall crew cuts new drywall around the switches (not the box) which made a 1/2 inch gap around the box. When I went to install the faceplate, it was impossible. I had to cut the drywall out from around the switch and redo it properly as well. They spent about 5 days out here to install 5 windows and 1 door. The fit and finish on the aluminum is really bad. There are paint issues and gaps in the frame, and the windows and slider are really hard to operate. I checked for plumb and the slider and a couple of windows are tweaked which, well, makes them really hard to open and close. They also broke one of the windows while installing it and told me they ordered a replacement at the same time. This is the replacement of the window that I broke - causing the whole window replacement thing to happen in the first place. Then nothing from them for about a month. They finally coordinated to have someone from the manufacturer come out who also confirmed that the windows were incorrectly installed and out of plumb – but he sprayed some silicone and called it good (which really didn’t help). He did nothing with the broken glass or the sliding door which has major paint defects and is poorly built and installed. Then nothing again until May. That’s when the fun really started. I get a call from Anna saying the manufacturer no longer sells aluminum frames (5 months AFTER the replacement window was “ordered”) and asked me if they could just replace the defective windows with vinyl, which I said if that were the case, they would need to replace all the windows with vinyl, so it wasn’t a mismatch in the same room at least. She didn’t say anything other than she was just the messenger, to which I told her I would like to talk to someone who can actually make decisions and speak for what the company is doing. We are dealing with fair amount of money in windows here, so I expect good quality and consistency, not windows and door that mismatched and hard to open. Then nothing again for another month. I finally got a text on the 10th letting me know Tammy was coming out with the glass guy, and it was confirmed between 10-1 on the 16th of June. June 16th comes and goes. No one comes out - and we are home all day, so this wasn’t a missed connection. This was no call no show from them. Well, fast forward to today (June 22nd). I get another text from Anna threatening to take me to court over not being able to complete the work. This is 9 MONTHS after I chose them, after they said they ordered the defective windows to replace the junk they installed, coming back 6 months afterwards saying they can’t get them anymore, saying they will come out with the guy from the glass company and then not show up. At this point I haven’t been able to finish inside around the broken windows and I would like to finish putting my house back together - I can’t keep waiting for the messenger to figure out the next delay tactic and am being forced to find another company to fix their mistakes. I reiterated to the threatening text that I need someone who can actually make decisions to contact me (now via text ONLY since everything will have to be in writing going forward). It’s been 5 hours and still nothing – maybe I can provide an update here in another month? If you chose this company – this is what you will get. Crappy service, horrible product and threats. And the window that started this all, even having been replaced, IS STILL BROKEN! Good luck!"
Jerry K on June 2021
We are an up and coming Home Remodeling company specializing in HVAC, Replacement Windows, Baths, and so much more. I welcome you to send an email or give us a call anytime. We are very flexible with scheduling and have installers and salesman with over 25 years of experiencing.
"We had accidentally broken a window while doing some remodeling in our kitchen and called RemodAz and a couple other window companies for competitive bids. We ended up signing a contract in October 2020 as we were told by the sales guy they would only take 6-8 weeks to get the job done, and they could do it faster than the others, because if we order now he can get the windows in as part of a large order for a local builder. At the end of December – with no communication other than me constantly inquiring where my windows are, they said they are having sourcing issues due to covid and could not give me an update, but could get me more information the next week after a call with the manufacturer, which I still didn’t get a call and was told it was my fault for not understanding that “next week” isn’t “next week” – it was the week after next week. Since we were adding a large sliding door and we had tile removed, we could not finish flooring until the door was in, so we had to keep deferring that install because we couldn’t get RemodAz to commit. Finally, towards the end of January they were out to install and man what a mess that was. Replacing 5 windows in the kitchen with two side windows and a plate glass window; replacing a window and a sliding glass door with a double slider; and then two windows in the front of the house. All with all aluminum frames, new windows and doors which is great because this matches the rest of the house. The door installation required a new header and some wire re-routing, and they wanted to just tie new wires with the old in the wall cavity which is not legal. I made them put a junction box in and I don’t think the way they crammed 8 wires into a double gang box was legal either but oh well. The new header goes in, and the opening is incorrectly sized for the door and it’s also sticking out a full inch on the left side into the room. 1 inch past the interior drywall and it’s clearly at an angle. They called a drywall guy out to patch the walls and he just laughed and left. They end up shaving the header down and just crumpled up some insulation and stuffed it in holes vs actually putting it into the wall cavity completely. I ended up redoing the insulation myself, oh and also had to supply the insulation and most of the wood myself along with quite a few tools. They ended up having an electrician come out to wire the new switches, and this was before the drywall went on, so the next set of drywall crew cuts new drywall around the switches (not the box) which made a 1/2 inch gap around the box. When I went to install the faceplate, it was impossible. I had to cut the drywall out from around the switch and redo it properly as well. They spent about 5 days out here to install 5 windows and 1 door. The fit and finish on the aluminum is really bad. There are paint issues and gaps in the frame, and the windows and slider are really hard to operate. I checked for plumb and the slider and a couple of windows are tweaked which, well, makes them really hard to open and close. They also broke one of the windows while installing it and told me they ordered a replacement at the same time. This is the replacement of the window that I broke - causing the whole window replacement thing to happen in the first place. Then nothing from them for about a month. They finally coordinated to have someone from the manufacturer come out who also confirmed that the windows were incorrectly installed and out of plumb – but he sprayed some silicone and called it good (which really didn’t help). He did nothing with the broken glass or the sliding door which has major paint defects and is poorly built and installed. Then nothing again until May. That’s when the fun really started. I get a call from Anna saying the manufacturer no longer sells aluminum frames (5 months AFTER the replacement window was “ordered”) and asked me if they could just replace the defective windows with vinyl, which I said if that were the case, they would need to replace all the windows with vinyl, so it wasn’t a mismatch in the same room at least. She didn’t say anything other than she was just the messenger, to which I told her I would like to talk to someone who can actually make decisions and speak for what the company is doing. We are dealing with fair amount of money in windows here, so I expect good quality and consistency, not windows and door that mismatched and hard to open. Then nothing again for another month. I finally got a text on the 10th letting me know Tammy was coming out with the glass guy, and it was confirmed between 10-1 on the 16th of June. June 16th comes and goes. No one comes out - and we are home all day, so this wasn’t a missed connection. This was no call no show from them. Well, fast forward to today (June 22nd). I get another text from Anna threatening to take me to court over not being able to complete the work. This is 9 MONTHS after I chose them, after they said they ordered the defective windows to replace the junk they installed, coming back 6 months afterwards saying they can’t get them anymore, saying they will come out with the guy from the glass company and then not show up. At this point I haven’t been able to finish inside around the broken windows and I would like to finish putting my house back together - I can’t keep waiting for the messenger to figure out the next delay tactic and am being forced to find another company to fix their mistakes. I reiterated to the threatening text that I need someone who can actually make decisions to contact me (now via text ONLY since everything will have to be in writing going forward). It’s been 5 hours and still nothing – maybe I can provide an update here in another month? If you chose this company – this is what you will get. Crappy service, horrible product and threats. And the window that started this all, even having been replaced, IS STILL BROKEN! Good luck!"
Jerry K on June 2021
We believe in serving the customer, not selling to them. That is why Airsuance, LLC is the first company of its kind to offer DISTRIBUTOR PRICING across the map. Whether you are replacing or repairing your heating and air conditioning system, we will make sure you get the best pricing possible. Give us a call or message us today. We would love to keep you comfortable in your home for years to come! We work extremely hard so that you don't have to.
"Fantastic job. The original install by builder was poorly ducked. The installers replaced and rearranged some of our ducts and now we have much better air flow. The unit is very quiet and powerful. The installers worked a very long day to get the job completed. We highly recommend their work and the price was most reasonable."
Stephen R on November 2020
We believe in serving the customer, not selling to them. That is why Airsuance, LLC is the first company of its kind to offer DISTRIBUTOR PRICING across the map. Whether you are replacing or repairing your heating and air conditioning system, we will make sure you get the best pricing possible. Give us a call or message us today. We would love to keep you comfortable in your home for years to come! We work extremely hard so that you don't have to.
"Fantastic job. The original install by builder was poorly ducked. The installers replaced and rearranged some of our ducts and now we have much better air flow. The unit is very quiet and powerful. The installers worked a very long day to get the job completed. We highly recommend their work and the price was most reasonable."
Stephen R on November 2020
Virtually diagnose and/or repair your appliances and HVAC units today without anyone stepping foot inside your home! Starting at $40 you can take control of your home appliance repairs via video chat with a certified technician when it’s convenient for you. Make an appointment today on our website. Neli's certified technicians will work with you to conduct either a diagnosis to find out what's wrong or a repair. You will use Neli’s advanced video chat technology during your appointment. Schedule your appointment today at nelihome.com or call us at 833-876-0900!
"This was amazing! I had no idea this service existed. After searching and contacting various repair places for my washer, this was the most cost effective option. I figured if it didn't work, my machine is old and I would be out $40, not the $100+ to have a tech come out and just diagnose the problem. I am pretty handy and my washer is old anyway, so if it is broken, I have to get a new one anyway. My tech, Steve, was great! He predicted what was wrong after listening to the machine, calmly walked me through dismantling the machine and when we got down to the motor, he was right! He sent me a link to the part I would need, and let me know to contact them again if I needed help installing it. My machine works even better than before it broke, its beautifully quiet and efficient. I will definitely be saving this company for any future repairs on appliances I may need. The service was $40 + the part cost, which was about $8."
Jennifer S on March 2025
Virtually diagnose and/or repair your appliances and HVAC units today without anyone stepping foot inside your home! Starting at $40 you can take control of your home appliance repairs via video chat with a certified technician when it’s convenient for you. Make an appointment today on our website. Neli's certified technicians will work with you to conduct either a diagnosis to find out what's wrong or a repair. You will use Neli’s advanced video chat technology during your appointment. Schedule your appointment today at nelihome.com or call us at 833-876-0900!
"This was amazing! I had no idea this service existed. After searching and contacting various repair places for my washer, this was the most cost effective option. I figured if it didn't work, my machine is old and I would be out $40, not the $100+ to have a tech come out and just diagnose the problem. I am pretty handy and my washer is old anyway, so if it is broken, I have to get a new one anyway. My tech, Steve, was great! He predicted what was wrong after listening to the machine, calmly walked me through dismantling the machine and when we got down to the motor, he was right! He sent me a link to the part I would need, and let me know to contact them again if I needed help installing it. My machine works even better than before it broke, its beautifully quiet and efficient. I will definitely be saving this company for any future repairs on appliances I may need. The service was $40 + the part cost, which was about $8."
Jennifer S on March 2025
Schwarder Construction is a general contracting company with a highly skilled team of management, craftsmen and sub contractors. Our team of professionals will meet all your needs from planning, renovations and building new residential and commercial buildings. We know how important it is to stay within the budget, provide quality work in a timely manner.
"I cannot say enough about Aaron Schwarder and Schwarder Construction. We bought a home that had not been updated since 1964. Plumbing included. Aarons crews redid both baths and the kitchen. Beautiful bright Carrera look tile, white counter tops, beadboard, wainscoting. New light and plumbing fixtures. Kitchen went from dark and cave like with fluorescent lights in plexiglass recessed ceiling thing, to raised ceiling, high end appliances, beadboard cabinets and an open to the dining room floor plan. Aaron was not satisfied with the cabinet surfaces and repainted them himself. All custom cabinets. Very important to me is the comfort level of having people working in my home. It can be awkward, to say the least. Aaron's guys are very respectful and always clean up at the end of the day, even if they are coming back in the morning. They were very careful not to let the animals escape. Recently I called the home depot pro desk with some questions about installing a new entry door and the first name they gave me was Schwarder Construction. I was raised to believe that a man's word is his worth. You can take Aaron at his word. 5 stars only because you cannot rate higher."
Nancy m on March 2022
Schwarder Construction is a general contracting company with a highly skilled team of management, craftsmen and sub contractors. Our team of professionals will meet all your needs from planning, renovations and building new residential and commercial buildings. We know how important it is to stay within the budget, provide quality work in a timely manner.
"I cannot say enough about Aaron Schwarder and Schwarder Construction. We bought a home that had not been updated since 1964. Plumbing included. Aarons crews redid both baths and the kitchen. Beautiful bright Carrera look tile, white counter tops, beadboard, wainscoting. New light and plumbing fixtures. Kitchen went from dark and cave like with fluorescent lights in plexiglass recessed ceiling thing, to raised ceiling, high end appliances, beadboard cabinets and an open to the dining room floor plan. Aaron was not satisfied with the cabinet surfaces and repainted them himself. All custom cabinets. Very important to me is the comfort level of having people working in my home. It can be awkward, to say the least. Aaron's guys are very respectful and always clean up at the end of the day, even if they are coming back in the morning. They were very careful not to let the animals escape. Recently I called the home depot pro desk with some questions about installing a new entry door and the first name they gave me was Schwarder Construction. I was raised to believe that a man's word is his worth. You can take Aaron at his word. 5 stars only because you cannot rate higher."
Nancy m on March 2022
At Alltech Solutions, Inc we handle the indoor and outdoor comfort needs of Arizona's commercial/residential equipment and facilities. We are based out of Tucson Arizona and licensed with the Registrar of Contractors. Our specialty is providing rigorous HVAC-R restaurant repair. We also provide air conditioning repair for bars, markets, retirement homes, recreation facilities, schools, dwellings, etc. Our technically trained professionals provide complete cooking equipment repair and are available 24/7 for emergencies. We are a locally owned Tucson company servicing, maintaining, installing, and selling all brands of units.
At Alltech Solutions, Inc we handle the indoor and outdoor comfort needs of Arizona's commercial/residential equipment and facilities. We are based out of Tucson Arizona and licensed with the Registrar of Contractors. Our specialty is providing rigorous HVAC-R restaurant repair. We also provide air conditioning repair for bars, markets, retirement homes, recreation facilities, schools, dwellings, etc. Our technically trained professionals provide complete cooking equipment repair and are available 24/7 for emergencies. We are a locally owned Tucson company servicing, maintaining, installing, and selling all brands of units.
Common repairs for central vacuum cleaners include motor repair, electrical repair, and blocked filters. Central vacuum motor issues typically come with a burning smell and loss of suction. With these issues, you might need simple lubrication to keep it running smoothly, or for more extreme problems, you could need a motor replacement.
Electrical problems or losing suction strength, might be reasons to swap out electrical components for new ones. However, a local central vacuum repair professional can tell you the best plan of action for your system.
The average cost for central vacuum cleaner repair is $310, though prices can range from $120 to $500. Your total cost will depend on the type of repair needed and the type of central vacuum you own.
A minor motor repair, like lubrication, only costs around $50. However, if you need to replace your motor, you’ll be looking at a much higher price tag with a total of $100 to $500. Other fixes, like electrical work, are charged by the hour, which ranges from $15 to $55 per hour.
A central vacuum system can last between 10 and 20 years if maintained properly. The frequency of use and amount of maintenance dictate its lifespan. These central systems last significantly longer than portable vacuum cleaners, which last 8 to 10 years on average. Keep your central vacuum system in good condition by checking the hose, wand, and attachments for clogs and emptying the debris bag regularly.
The average cost to hire an HVAC contractor is between $50 and $150 per hour if charging hourly. However, some HVAC contractors will charge a flat fee by the type of service they are performing—for example, an inspection can cost between $150 to $500. Keep in mind that emergency repairs—which are made after business hours or around major holidays—generally cost more than scheduled repairs.
Yes, most states require HVAC technicians to be certified, and for good reason. Hiring an unlicensed HVAC technician could lead to poor quality work, costly future expenses, and potential code violations.
As you browse our pro listings, take note of the “Angi Approved” badge. Angi Approved businesses meet our standards for certification which include:
The owner, principal, or relevant manager passed a criminal background check
Required to have applicable state and local licenses
Maintain an average star rating of 3.0 or better on our network, if they have at least one review
Paying to advertise their services
Meeting any other eligibility criteria required by Angi
Keep in mind licensing is different from certifications. A license is a legal requirement to operate a business, while certifications are voluntary.