Arudge

Good to hear. I have zero actual experience so real live setups are always going to trump what anybody can dredge up from the net. Thankyou.

Just to add, i do not work for, or have any affiliation with Testo. I chose them because they appear to be the industry standard.

I spoke at length with a civil engineer friend about anemometers and MVHR, in his opinion the Testo 405I hot wire variety wouldn't be much good because of all the eddy currents set up by the diffuser, they were more for consistent and stable air flows found in in-line duct work, and even then there was a set procedure to the sampling. The link below gives a demonstration. In his opinion, the vane type was the only option. But here i learned something new. The supply and extract vents set up different eddy currents, that's why the Testo 417 come with optional two completely different funnels, one square and one round. There not for round vents and square vents, there for extract and supply. So making your own funnels may or may not give you the desired results. The link below gives an explanation. Hopefully this may be of help to others. Everyday is a school day. Andy.

I had a long conversation with a civil engineer last night regarding this, he came to the same conclusion. He went on to say that a vane type anemometer would work better, in his opinion the sampling area was too small and too many currents in the pipe for a hot wire anemometer, he'd also be inclined the reduce the pipe diameter to smooth out the flow.

Hello all. I've finally got my Vent Axia sentinel B MVHR unit running. My BC wants paperwork so I've no doubt they will want a calibration certificate for whatever device I use? Right now I have nothing, do those cheap vane type meters on fleabay actually work or are the hot wire variety better?

or am I just wasting my time as the windows are old and house isn’t airtight? You've already proved the benifits of your setup because you've got less condensate on the windows. What you have to consider is that the level of damp in your house is also in the plaster, the furniture, your clothes and anything that's absorbs moisture, it will take weeks to dry out, but it will. You won't get perfect results because you don't have air tightness, but if your system is balanced you'll achieve more than some say. Think about it, if you have more supply than extract then that positive pressure will push out through whatever is leaking. If you have more extract than supply then the slight vacuum will suck cold air from outside through the same leaky bits, and you'll feel that as a draft. Keep the system as balanced as reasonably possible.

Hello All. I'm at the back end of a two story extension (self build) on an older property (circa 1785). Taking down old extensions along the way. I've gone to great lengths with insulation, VC foil, everything silver tape sealed to everything else, MVHR. I realise I won't get full benefit as only 2/3 of the structure is covered, but it's already made a huge difference. I'd converted a large garage into a one bed detached annex about 7 years ago, same MO, floors taped to walls taped to ceiling, insulation everywhere, small MVHR unit. It was a resounding success, warm as toast, no condensation, no mould, cheap to run. My in-laws were chuffed to bits! It was because of the success on the annexe I started on the house, but I underestimated the amount of work and the cost involved, I won't be doing this again!