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Questions & Answers

Two Motors - Which One is Working?

I have Silent master S-5 120volts unit. I want to find out how many motors are working out of two it is supposed to have? If one motor is out how do i find it out which one I should order? At the bottom of the filters in the Tank there are two approx 2" holes and one of it is spinning..what does it mean? Thanks for your patience till i find out all about the unit. I must tell you that you have a very nice layout and complete information on-line for anything one might need on CV systems. Thanks. VPPatel

Thank you for the kind comments. To find the bad motor look into the two holes from the top after removing the filtration. When the vacuum is turned on, the good motor will spin right away but the bad motor lag behind. The replacement and instructions here. Both motors in the vacuum are the same motor

Silent Master Owner's Manual

Hi, I recently purchased a house that is fitted with a Silent Master unit which was installed in 2007. I need to acquire an instrction manual but cannot find this model on your website. On the serial plate the model number reads as follows: s4for. It also advises that it is 7amps 50/60hz. Please can you advise what model this is, and is it the correct unit for a house of about 220 sqm. Regards, Varian Rossouw - Johannesburg, South Africa.

You can find the Owner's Manual here,

Motor Going Bad?

I have a silent master S2. The unit is making a loud whining noise. All the outlets seem to be clear, but the noise is scary. Is the motor bad?

Most likely the motor is bad. You can keep using the system until it fails, without harm. Or you can contact a local dealer for help, or call us and we'll be able to listen and diagnose over the phone.

S3 Motors or Replacement?

Hello, I own a 240v Silent Master S3 with a manufacture date of 5/94. One of the motors died today! How long do you expect the life span of the S3 to be? I see motors cost about $200 each. Would it be more cost effective to replace just the motors or buy a complete power unit? Is shipping included in the prices I see on your web site? Thank you


Hello, a new SilentMaster unit with this power is just over $1000. We suggest replacing the motors for under half that. The motors are here in this link,221,720HF-5,how2mtr. Motors last for about 800-1000 hours. Your unit is old enough to have those numbers. Shipping for the motors is around $20 and there is no tax outside California.

Clean Foam Filters?

Do the foam filters ever have to be cleaned in an S5? Mike in Mass

Hi Mike, the three filters (older units) or single filter (new units) under the paper / cloth bag in the SilentMaster units can be beaten out every five years or so. That is it.

Specs for Model S4?

Why do I not see specs for the S4 on yor website. Where can I find them? Mike in Massachusetts

Hi Mike the S4 is replaced with the S44. You can find the specs though by clicking on the replacement motor here

Intake and Exhaust Ports on Power Unit

Trying to determine which is the inlet and the exhaust on the Silent Master. Thanks John


The intake is at the top, one on both sides. Use both or cap the other with the included cap. The hinged valve at the top center is a utility port for connecting a hose to vacuum your basement, or car and garage. Turn the power unit on via the switch on the bottom right side. The two port at the bottom side are exhaust ports. You don't need to vent the machine but if you do please use both. Hope that helps!

Explaining Water Lift and CFM

Can you please explain the difference between CFM and waterlift and their overall relationship to a vacuum's "Power" or Air-Watts ? Tim Chesapeake, Va


You need both measurements for an effective vacuum. Waterlift is something you and I can produce very well. Take a plastic bottle and suck the air out of it. The sides crush in. In fact, a person can produce more waterlift, more sealed suction, then any residential vacuum. But the difference is in the air movement or CFM. You need to move huge amounts of air to be a good vacuum. However, waterlift is very important because air movement will die out if it doesn't have force behind it. The air will stop moving without waterlift. In any vacuum, the air has to move through turns, go through reduced orifices, and ultimately lift debris and pull it in. None of that is possible without the strength behind the air flow. Without waterlift CFM slows down and the vacuum is not effective. Central vacuum motors can produce high measurements of both, which makes them so effective.

Adding a Garage Kit

I own a Silent Master S5 and would like a garage kit. I do not see where and low voltage or outside hookups are on my unit. The literature from the unit is not detailed on this matter. Could you recommend a garage kit that is applicable? Thanks Karl BP Washington


The Silent Master has a switch on the back right bottom side. Plug any of the garage kits into the valve at the top front of the can and then toggle the vacuum unit on. Hope that helps and here are the Garage Kits that you can use with your system.

Upper Level, Quiet System

I have a 1600 sg ft house on 2 levels that is currently equipped with a central vac that I wish to replace. We have no carpet in the house. Floor covering is all ceramic tile so we have no need for a powerhead for carpet. We live out in the country so have to deal with dirt, sand and of course dog hair. I would like a recommendation for an upper level(quality) and quiet system. Please advise. Jim


The SilentMaster S560r is what you are looking for. Patented, very quiet vacuum with a huge amount of suction and air movement. See the stats and compare them to any vacuum in its amps class.

Cyclonic vs Filtered Cyclonic vs Bag

I have heard of True cyclonic, and filtered cyclonic systems, with no bags, how is yours different, and is it better, and if so what way?


Central vacuums are the best way to clean a home. There are different ways to filter them and they are detailed in our Filtration Analysis Article. We have a preference, but we have more of a preference for every home to clean with a central vacuum no matter the brand!

240 Volt Models Wiring Options and Receptacle Type

I am considering purchasing a S720r2 240 volt. Is this model hard wired; 3 prong or 4 prong 240 volt? Thanks Donna, MA


The S720r2 can be hardwired to three wires into a 240 volt system or plugged into a three prong 240 volt receptacle which has a vertical and horizontal and a ground.

Fit Nutone Pre-Plumbing and Connections?

We're buying a new home and are interested in the Silent Master, However, our builder offers Nutone as it's only central vac brand option. We do have the option of having the piping pre-installed and incorporated into our mortgage without purchasing the Nutone unit and parts. Then once we move in we would buy our central vac. My question is, can the piping that would fit with the Nutone system work with M.D.'s Silent Master hose, or is piping different for each manufacturer? Can you write back promptly before noon tomorrow, Friday, if possible, as we're meeting with the builder rep to discuss this among other electrical wiring options for our home tomorrow. We didn't think we were interested in a central vac until reading your website and consumer reports. Thank you!


Go ahead and have them pipe for the Nutone vacuum system and install the wall vacuum inlets. All our hoses will fit. If you have a choice, ask for the 110 volt electrified outlets, but you don't have to use them. For the Silent Master, simply have them stub the pipe into the area for the central vacuum location. They will also stub-out the low voltage contact wire. When your home is finished you can easily hang a Silent Master vacuum and hook it up. You will need a couple elbows and some pipe which will be compatible assuming they use the standard 2 OD central vacuum pipe (not SCH40 PVC). If they use SCH40 we have an adapter that allows it to go to central vacuum pipe and elbows that connect to the central vacuum unit. If your home is under 6,000 square feet you will need a 20 amp regular electrical outlet within 5 feet of the vacuum unit. If over that size home, ask for a 30 amp circuit with a NEMA 5-30 socket. Let us know if you have any questions.

240 Volt More Powerful?

What's the difference between a 110V and 240V system? I was told that a 240V system would have more air-lift, but I don't see that reflected in the specs for the Silent Master -- why not? Thanks! -- Amanda


Take a look at the specifications for each power unit model. Sometimes the 110 volt model is more powerful and sometimes the 240 volt model is stronger. It all depends on what the motor manufacturer can produce, but one is not always stronger than the other. If you are getting power put into the wall valves that will always be 110 volt to power the carpet beater head.

Lowest Operating Temperature

What is the minimum temperature the SilentMaster operate in? I want to install one in a garage that is not heated during the night and temps can get pretty cold. Thanks Don


We have not found a non-operating low temperature. The vacuum works perfectly fine in extreme cold and heat.

How Many Outlets Needed?

Nancy, Paducah, KY: I am building a new home - 1600 sq feet. Does there have to be an outlet for the suction hose in every room or can one outlet do for the entire house; How long are the hoses?


Most likely the home would need two traditional wall inlets with a 30-foot long hose, or a single 50-foot Hide-A-Hose. Of course, you could do one of each as well. Install the best cleaning options for your home and preference. We highly recommend a traditional vacuum inlet to cover carpeted rooms with an electric powered vacuum head. Hide-A-Hose only allows for non-electric vacuum heads which do not clean carpet as thoroughly.

Replacement Bags

I have a SilentMaster in my garage that came with my house when I bought it. I need to order more bags and I don't see any distinguishing model #'s on my unit. How do I tell which model I have? Thank You, Michael R Moore


All models in SilentMaster take a disposable bag, either an open or closed one. You can find both bags choices, along with upgrade options, on our Paper Filters and Bag Filters page.

Rating the SilentMaster



The consumer guide only did one article on central vacuums. We were consulted, as well as other manufacturers, but we feel the tests were not done well. Being a niche product not well understood by the public it is easy to see why there is confusion. We have written a rebuttal that will help you evaluate the best system for your needs. Also, remember that our unit is designed and assembled in the USA, is all steal, powder-coated completely, quiet and powerful. Here is the rebuttal in Microsoft Word

Replacing Bottom Emptying Central Vacuum Such as Beam

I currently have a Beam central vacuum and I am considering replacing the power unit with a SilentMaster. However, I need the specifications to determine if this can be done


Silent Master is a great choice, but our Air Master Models fit directly in place of any Beam model and are a great choice for all bottom emptying power units.

Exhausting the SilentMaster

There are two exhaust ports on my unit and I want to install piping to have the exhaust sent outside my home instead of directly into the basement. I cannot find any drawings showing this exhaust configuration. How do I handle the two ports? Two separate pipes?


There are two exhaust ports and both need to be exhausted. We have seen some clever methods that combine both into a larger pipe. Also, try to keep the exhaust runs under 20 feet long.

Changing from Beam to SilentMaster

If i change from a beam to a silentmaster can I use my low voltage or can i just use the power from the cord on the stealth?


Upgrading the main power unit in the garage or basement: Use the same electrical wall socket for power and also plug the existing low voltage wire into the SilentMaster. Upgrading the hose and power nozzle: The Stealth Kit plugs directly into all Beam wall inlets. The kit comes with either a direct connect 110 pin hose or a pigtail corded 110 volt version (to plug into a nearby electrical wall outlet).

New Homeowner with SilentMaster

We bought our house - with this wonderful built-in Silent Master S2 vacuum system - about a year ago, but I have no instruction manual. I used the one replacement bag the sellers left, so I'm ordering the 721 bags. The Q&A above helped with how to deal with the cloth filter and all, but I'm not clear about anything else that needs changing or other maintenance I should be doing. Is a manual available? I do notice that the rubber gasket on the canister cover is coming loose and allowing air leakage. Can I get a replacement gasket? John Phillips Camarillo, CA


Congratulations on the new home and owning a SilentMaster. You bought the correct bags, the #721H-5 (now replaced by 720HF-5). Here are some resources for you: Silent Master Manual, accessories, replacement parts and upgrades, replacement lid gasket. If you need anything else please let us know. The system is really easy to take care of - just replace the bag!

Compare to Beam...Only Need Stealth?

How do you feel that your product compares to beam? I'm thinking about replacing my old unit and i want to get something that will work better than the beam unit that I have. Will I be happy just buying the new stealth unit to go with my beam or would i be better off buying a new silent master also? I have about 2000 sq ft


Starting off with the Stealth Kit is a great way to go and less expensive than replacing a functioning vacuum. When the Beam dies consider the Silent Master for its filtration, quietness, power, and quality.

Quote for 4300 sqft Home

My home is approximately 4300sf. - Which Model Silent Master do you recommend? How much current is needed 110v or 220v? What is the cost? - What home accessory package do you recommend? - I have wood floors and tile. - I have window blinds and ceiling fans. - I have pets - I also would like the car kit. Could you give me a list with prices of the items listed above. Thank You

Hello, thank you for considering the SilentMaster Central Vacuum! Please call us for list prices on vacuum units. We'd rather not put that here, plus the prices may change but this posting will not so we have to be general. Nevertheless we will answer your questions. You have the choice of voltage, we make the unit in both. For that size home we recommend the model S4 or S2, but lean towards the S4 for it powerful suction over super high air movement. When it comes the kit you need, if you have any carpeting (especially with pets), the best solution is the electric powered kits, and the best one is the Stealth Kit. It sells for around $550 and includes what you need for the items to be cleaned in your home. We do make some specialty items but you have to get these right away. The car, or garage, kit comes in original and ultimate and cost from around $100 to $200.

Come with Attachments?

Does the silent master central vacuum come with the attachment's, or must these be purchased separately?


The Silent Master is sold alone so that you can decide what attachments are best for your home. Having the right attachments makes the difference when owning a central vacuum.