I think many of us recall a thread where Trebor suggested a modification for the Sanitaire upright that improves its performance. The modification involves drilling two 1/8" holes on the back walls of the air-intake nozzle in order to increase airflow and reduce the clamping effect Sanitaires are known for.
Well, I finally found time to do this mod. Here are my thoughts:
After drilling the holes, the suction across various spans of carpet seems more consistent. Before, the vacuum seemed to suck more onto the carpet at points where the nap was raised somewhat. Conversely, it would suck onto the carpet less where the wood subfloor was uneven, breaking the seal. The modification results in a consistent feeling suction that doesn't feel like its clamping onto the carpet.
Suction around the perimeter of the nozzle seems reduced. Before the modification, the VGII brushroll would bounce dirt and debris up and down in front of the nozzle. The suction and airflow would pull the dirt in from a good distance around the perimeter of the nozzle. Post modification, the VGII still bounces the dirt, but the nozzle has to be nearly on top of the dirt before it sucks into the vacuum. I suppose this is to be expected as some of the airflow is diverted through the little holes. There is simply less air moving directly under the bottom of the nozzle because of it. I still feel that there's plenty of airflow and suction under the nozzle. It's just a matter of covering the entire carpet surface with the nozzle in order to suck in dirt.
Of course, I think this mod is a compromise. That is, if the nozzle clamps onto the carpet as Sanitaires are prone to do, airflow is choked off resulting in reduced cleaning. This mod insures that the clamping does not happen. So this is very good in this situation. But because the holes divert some of the air, the amount of air entering directly under the bottom of the nozzle is lessened. Given that there's enough clearance for airflow in the first place, there will be less pull underneath the and around the nozzle.
So it seems that this mod is especially good for those vacuuming on medium to high nap carpet where clamping can be an issue. In my building I have low nap commercial carpet, so maybe this mod isn't as useful. I like the consistent feel of the suction that the mod provides, but seeing less dirt get sucked into the nozzle at a distance gives the impression that the vac is cleaning less effectively. That is probably not true, but one does get that feeling not seeing the bouncing dirt get pulled in from as far away.
One caveat with my observations is that I inadvertently poked two different diameter holes in my Sanitaire. That is, I was using one of those conical stepped bits. I started with 1/8" tip but realized I went in too deeply. The result is that the hole on the outside surface of the nozzle's wall is 1/8". The hole on the inside surface is 3/16". I don't know if this makes a difference or not as the ultimate aperture is 1/8". It just expands out to 3/16" on the side that faces the brushroll.
I'd be interested in hearing your observations about this modification. I'll report back as I use the vacuum more.
Thanks to Trebor for a useful modification.
Well, I finally found time to do this mod. Here are my thoughts:
After drilling the holes, the suction across various spans of carpet seems more consistent. Before, the vacuum seemed to suck more onto the carpet at points where the nap was raised somewhat. Conversely, it would suck onto the carpet less where the wood subfloor was uneven, breaking the seal. The modification results in a consistent feeling suction that doesn't feel like its clamping onto the carpet.
Suction around the perimeter of the nozzle seems reduced. Before the modification, the VGII brushroll would bounce dirt and debris up and down in front of the nozzle. The suction and airflow would pull the dirt in from a good distance around the perimeter of the nozzle. Post modification, the VGII still bounces the dirt, but the nozzle has to be nearly on top of the dirt before it sucks into the vacuum. I suppose this is to be expected as some of the airflow is diverted through the little holes. There is simply less air moving directly under the bottom of the nozzle because of it. I still feel that there's plenty of airflow and suction under the nozzle. It's just a matter of covering the entire carpet surface with the nozzle in order to suck in dirt.
Of course, I think this mod is a compromise. That is, if the nozzle clamps onto the carpet as Sanitaires are prone to do, airflow is choked off resulting in reduced cleaning. This mod insures that the clamping does not happen. So this is very good in this situation. But because the holes divert some of the air, the amount of air entering directly under the bottom of the nozzle is lessened. Given that there's enough clearance for airflow in the first place, there will be less pull underneath the and around the nozzle.
So it seems that this mod is especially good for those vacuuming on medium to high nap carpet where clamping can be an issue. In my building I have low nap commercial carpet, so maybe this mod isn't as useful. I like the consistent feel of the suction that the mod provides, but seeing less dirt get sucked into the nozzle at a distance gives the impression that the vac is cleaning less effectively. That is probably not true, but one does get that feeling not seeing the bouncing dirt get pulled in from as far away.
One caveat with my observations is that I inadvertently poked two different diameter holes in my Sanitaire. That is, I was using one of those conical stepped bits. I started with 1/8" tip but realized I went in too deeply. The result is that the hole on the outside surface of the nozzle's wall is 1/8". The hole on the inside surface is 3/16". I don't know if this makes a difference or not as the ultimate aperture is 1/8". It just expands out to 3/16" on the side that faces the brushroll.
I'd be interested in hearing your observations about this modification. I'll report back as I use the vacuum more.
Thanks to Trebor for a useful modification.
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