Thanks GTE and everyone for your advice/opinion, remember one thing, it is afterall a DIY effort, and one of the things is to use what I have available, a true DIY strategy, as I am not a professional builder, so there is no question of having proper industrial type of tools. nor the experience, so it is a learning curve as well as you go along.
Henry managed to do a pretty good job I would say, only that filter clogs up and the suction diminishes to about 20%, which means it is still capable of sucking fine dust leaving slightly heavier debris behind, I can live with that sine the main thing is the finer dust I want to get rid of.
But then , I found that when the suction gets low, switch off, whack the drum a few times to shake off clinging dust which falls to the bottom, and then resume, and the suction improves to about 50% which now means it is ready to suck small to medium pieces of debris, and the finer dust, until it fills up and needs emptying, but it is mostly (90%) dust rather than small pieces of broken slates or plaster pieces.
So in all I had to switch off and shake off dust about 5 times, and managed to suck up approx 15Kg of dust, clearing about 4 square meters of area, so at this rate I should be able to complete the job in about 3 to 4 days, taking it easy and spending about 2 yo 3 hrs a day.
Finally, when you empty the contents into a black rubbish bag, most of the dust is transferred into the black bag, very little spillage into the air, however, the fine dust stuck on the filter has to be removed manually with a brush, this would get air born and I have to avoid this at all cost, and is no good brushing it off, so this is where DC07 comes handy, as it only has to suck up a small amount of very fine dust clinging to the Henry's filter, and this cleans the Henry filter very well, keeping minimum down time as you don't then have to wash off the filter and wait for it to dry, you could then get back and start using it again after emptying Henry, this way you can get almost 90% suction. (you would get 100% suction when filters are washed properly and dried thoroughly.
I also went to
Wickes today, and bought another Henry, just in case, at £39.00 and this is slightly different to previous model, it comes with 3 cloth type filters bags that slip over the motor, that means you could wash one and allow to dry and can use a 2nd filter and a 3 rd one and by which time the first one is dry.
I have also bought a proper filter cartridge for my old Henry as opposed to using foam type filter since foam filter is no good for very fine microscopic dust particles, hence why I had to wrap several layers of other paper type filter material as used in other hoover bags.
But yes guys getting there, and I will be well please when all that deep pile of real thick black dust is got rid of and I can sleep in peace.
