<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Times New Roman">I have a constant air flow rate of 1.0 1/h for working days (7:00-18:00). All other times the air flow rate is constant 0.5 1/h.</FONT><FONT class="Apple-style-span" face="Times New Roman"> </FONT></DIV></BLOCKQUOTE><BR><DIV>This caught my attention - one litre per hour is a really really small number in</DIV><DIV>terms of air flow for any zone bigger than the box an ipod came in. This would</DIV><DIV>be held as an equivalent m^3/s which is at the 4th decimal place and</DIV><DIV>the 0.5 litre per hour might be at the 5th decimal place so it might</DIV><DIV>be possible that simple rounding errors and numerical noise are factors.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>And a change in volume in a zone could easily result in a bigger</DIV><DIV>flow than this fixed rate. Suggest a run with 10 litres per hour etc.</DIV><DIV>to see if the glitch goes away.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>-ESRU</DIV></BODY></HTML>