Central vacuum

[cheesewonton]

For a well installed system, I don't think the ideal power of the power unit corresponds very well to home size, for the vast majority of homes at least. There losses in pipes in the walls should be relatively small compared to the hose and cleaning head/attachments.



That's interesting. I wonder if you would get more cleaning-relevant performance from having the two motors in series instead of in parallel.

My question is, do you really have more cleaning power at the end of a 30 something foot long central vacuum hose after it has gone through another 50-100 feet of pipe in your walls than you have at the end of the hose from a good canister vacuum? Are all those motors, tubing, wiring, extra power consumption and money getting you more cleaning power at the end of the hose?

 

[Hatsuwr]

My question is, do you really have more cleaning power at the end of a 30 something foot long central vacuum hose after it has gone through another 50-100 feet of pipe in your walls than you have at the end of the hose from a good canister vacuum? Are all those motors, tubing, wiring, extra power consumption and money getting you more cleaning power at the end of the hose?

Personally, my favorite thing about central vacuums is that you can vent the exhaust air outside, but regarding performance, yes, you will be getting more cleaning power at the end of the hose in most situations.

Usually when using a vacuum, you will be creating a restriction around the area being cleaned to increase the air speed at the area being cleaned. This restriction means you will have a much lower airflow rate than just an open hose end. Because of this lower airflow rate, the pressure losses in the pipes and hose will be decreased.

These losses are more significant at higher airflow rates. Sometimes I use my central vacuum for fume extraction when soldering — that's about the worst case for a central vacuum, but I'd guess that even then it would beat (or at least be competitive with) most canister style vacuums. Plus, with the canisters you need to take into account power loss from voltage drop in the power cable. This loss will be greater with more powerful motors and during higher loads, but you could be looking at a 10%+ loss in power from this.

 

[centralvacguru]

Any chance you have a picture of the old MD unit? What is the serial number?

 

[ultralux88]

It's a model E, serial 188. I know I talked to you about this one a couple years ago. Found on Facebook marketplace out of Colorado Springs. Was quite a treat, as I was assuming I'd have to go through all kinds of nonsense to find one and get it out of California somewhere, as an early MD was something I did really want.

 

[cheesewonton]

Personally, my favorite thing about central vacuums is that you can vent the exhaust air outside, but regarding performance, yes, you will be getting more cleaning power at the end of the hose in most situations.

Usually when using a vacuum, you will be creating a restriction around the area being cleaned to increase the air speed at the area being cleaned. This restriction means you will have a much lower airflow rate than just an open hose end. Because of this lower airflow rate, the pressure losses in the pipes and hose will be decreased.

These losses are more significant at higher airflow rates. Sometimes I use my central vacuum for fume extraction when soldering — that's about the worst case for a central vacuum, but I'd guess that even then it would beat (or at least be competitive with) most canister style vacuums. Plus, with the canisters you need to take into account power loss from voltage drop in the power cable. This loss will be greater with more powerful motors and during higher loads, but you could be looking at a 10%+ loss in power from this.

I don't get it. We are talking literally the exact same attachments, wands and power nozzles on the ends of a central vacuum hose or a canister vacuum hose. In fact several of my vacuums like the Oreck Dutch Tech, Patriot and Miracle Mate literally have standard Plastiflex central vacuum hose handles and I use a variety of different central vacuum wand and power nozzle combos with them. How is this different from a central vacuum? Where is the difference in restriction?

 

[Hatsuwr]

I don't get it. We are talking literally the exact same attachments, wands and power nozzles on the ends of a central vacuum hose or a canister vacuum hose. In fact several of my vacuums like the Oreck Dutch Tech, Patriot and Miracle Mate literally have standard Plastiflex central vacuum hose handles and I use a variety of different central vacuum wand and power nozzle combos with them. How is this different from a central vacuum? Where is the difference in restriction?

I'm not talking about a difference in restriction between the two, I am talking about the intentionally created restriction that directs the airflow to the area being cleaned. That particular restriction can definitely be assumed to be the same between the two types of vacuums.

 

[reactor]

Unfortunately, I don't have the equipment to measure CFM and water lift for a central vac versus conventional vacs, at hose end I can only speak through experience. I have installed a central vac into the majority of my homes and condos in my past. My current home, purchased late January, does not have one, and I have purchased a power unit, but have not purchased the pipe/tubing yet to install. Also, I put one into two of my sister/brother-in-law's homes. My dad installed one in our house when I was young. Later in their elder years, my parents moved and I surprised them with, and installed, a central vac in their new home. ---- So my interaction with central vacs is experiential as opposed to theoretical. I have had 120 volt units, and my parents unit that I ininstalled (Beam) was a top of the line 240 volt. ---- There is no reason to debate as suction is directly related to the size (aka power) of the central power unit. If you just want general cleaning then go with a builder grade unit. My parents first (I am going from memory) was a Sears Kenmore built by Whirlpool. The suction was approximately 110" (sealed water) and CFM I believe was 120". Not a very powerful unit. But it outperformed and portable/canister my mom ever had, in her perspective, which is what counts, and she loved it. Was the suction greater than a canister at the end of the tubing a hose? it is hard to say. It was at least as great if not greater than any canister we ever owned. I could place the hose opening on the palm of my hand, and the suction would snatch in and I could move my hand up and down and the hose "hung on". Not a very scientific measurement, lol. But as a kid it was fun. ---- On the other end of the spectra was the one I purchased and installed for them some thirty years later. The Beam was a 240 volt power house. Once again I don't recall the specs.
The suction and airflow at the end of the tubing and hose (for a 2400 square foot house) exceeded any canister or upright vac. It was so strong, my mom couldn't push the power head on the carpet, unless the suction control/relief valve, on the hose was opened a bit. The suction and the end of the power head was so powerful that it pulled the head down into the carpet and held it. I could use it without bleeding the suction, but it was VERY hard to push, so I usually bled a tad of suction off just to ease the pushing a bit.------ So basically, as in any other device/machine/appliance you get what you pay for.---- Even in the low end of the spectrum where you are getting suction approximately equal to an average canister, the ease of use, the quietness, and the zero recirculation of dust particles certainly makes a central vac worth every penny. ----- Some in here have indicated they don't like a central vac. That's cool. Others, like me, won't live without one. Whatever floats your boat, lol. If we were all alike it would be a very boring world.