Hi John, An interesting test would be the CFM and lift readings when the wand is on the carpet. This would give definitive answers about what is best in use.
The CFM meter could be mounted in a piece of hose to give a reading and the Lift reading could be taken off of a hose connector with a hole in it.
Let us know if you fancy having a go.
Hey Robin , testing at the wand would be best alright . Measuring the lift like that is easy enough , putting a digital cfm meter in the system is a bit trickier .
The cfm guage would need to be inline , within the vacuum system , easy to do with the omega style inline gauge but with the digital meter like mine its barely possible , I could try and put a connector each side of the meters vane and seal it with duct tape , it would be crude but might work .
Ashbys had some great inline cfm wand on carpet measuring videos on youtube a couple of years back , only problem was the omega guage they used proved inaccurate under vacuum .
Heres an alternative , i took the below pic from tmf , this guy has measured the operating lift with the wand on the carpet and then made a round hole in the plastic cap at the size that matched the result he got for operating lift , so he is simulating the wand on the carpet but he can now place his digital cfm meter over the hole .