wookey, I've spent tens of hours searching the web for easy, beginner-level, stuff on Linux. It just isn't there! I'm not ranting, as you put it, simply stating a fact. There are masses of Linux forums and groups around, but all seem to be aimed at people who already understand the fundamental structure of Linux and who use arcane language that means little to an outsider. You mentioned Unix - does that mean that if I get a book on Unix I'll get a better understanding of Linux? If so, why isn't this info available more readily?

As another contrasting example, I recently I switched to using PICs for simple ucontroller tasks (data logging, primarily). The difference is marked, I was able to get hold of beginner-level information, written in plain and easy to understand language, within a few minutes of starting to look. There are more beginner-level tutorials around, plus useful data sheets and PIC-centric friendly forums, for this than there are for Linux. The Linux community appears a bit closed to those who don't yet understand the basics of the way it is structured and works.

I fully appreciate that those "in the know" already won't begin to understand the extent of the Linux information gap and it seems that effort is being expended by a lot of people to make Linux look and feel like Windows (goodness only knows why, as that just glosses over the interest I have in understanding it at a fundamental level). I fully accept that I'm an non-typical user in some respects. It would seem that a lot of effort is going into making some flavours of Linux look slick and offer office, browsing and email capability that is virtually indistinguishable from the expensive products from Microsoft et al. This is all well and good, but if you are a beginner and want to find out the basics it is extremely difficult to get hold of a comprehensive guide, written in simple, plain, English, that takes you through how Linux is structured and the detail of the command set. You have to be wholly unfamiliar with it to begin to appreciate just how impenetrable it looks from the outside.

Your approach to my posts is pretty typical of that from the Linux community as a whole, without wishing to be rude in any way. I've already said that I've taken a lot of time to research Linux on the web, I've taken the time to download and install Virtual Box and Debian (after a heck of a struggle), I've spent money on buying two machines that came with Linux installed by default. I don't think those actions are anything but those of someone with a commitment to use it, do you? I've explained some of the difficulties new users like me have and how confusing the whole Linux scene seems to be, yet instead of pointing me to a source of useful basic information you've chosen to assume I was ranting when all I've been seeking is some fundamental, beginner-level information.

Thank you!

Now a return to your regular data feed!

Here you can see the flat room temperature for the few days that the house was empty. (Will update from the other sensors when I put decorations back in the loft, etc...)

Rgds

Damon

Builder (+ sparks) coming on Monday to look at and adjust MHVR.

However, it's evident from the attached graph that the fluctuations in room temperature have dropped now that we need not open the windows daily to get adequate ventilation.

At when measured earlier today the boy's room temperature was higher (and RH lower) than the bathroom where the MHRV is (at the other end of the corridor).

Rgds

Damon

Basically, post MHRV the room minimum temperature each day is a little higher (as we're not throwing windows open in the morning to clear the smog) and the temperature range during the day may have reduced a little (ie are more stable).

We still get bad condensation when overnight is below about 5C (some at 6C, none at about 10C), and humidity rises to not much short of 80%RH upstairs, but drops slowly during the day while people are out rather than holding the duvet up, snoring. 73%RH right now for example.

I will need to work on other tactics to reduce humidity: for example we now are running the dehumidifier in the kitchen when drying laundry on racks.

Jury still out as to whether the MHRV actually saves heating compared to selective window opening each day, but it in any case seems to be doing no harm along with the IWI.

Rgds

Damon

The fan is ~20m^3/h on trickle, and the house is a little over 160m^3 by volume, so a complete change c/o of the fan under optimal conditions would be 8h.

I did try to set the fan threshold to actively control the humidity, but that made it come on occasionally at night and even when someone just walked into the bathroom to admire themselves in the mirror, so was too annoying.

The bathroom itself does benefit from the automatic eviction of the moisture during a shower or bath, and is back to normal within (say) 30 minutes of the shower/bath finishing.

Rgds

Damon

Everything I've dug out on ventilation over the past few months supports the view that 0.3 to 0.35 ACH is about the minimum for reasonable air quality and 0.5 to 0.6 ACH is about the maximum tolerable in terms of heating season heat loss.

FSAP 2009 seems to throw a wobbly if you go below 0.44 ACH I found, so presumably it has a BR compliance check built it.

This is the latest and final chart about my loft. There was a slight error on the loft space humidity reading (I inadvertently covered the sensor aperture ) but as there was never a condensation risk there anyway I am not worried.
So I am now quite happy that I do not have a condensation risk between the insulation and the roof as it has never once hit 100% RH and as I have halved the heating load (removed two of the four elements in the storage heater) since I insulated, I think this was a well spent £50 (and a days playing with itchy stuff and a stapler). And I still have all my loftspace to store stuff in and no worries about the wiring too.
Later on in the year I shall to a better analysis incorporating some HDD data to adjust for this warmer winter.

I have other plans for these sensors, almost finished my home made MVHR unit, that seems the next logical place to test.
Can't use them to log the end of time as they only go down to 253K, so may have to get a better device for that.

Working on fixing one source by moderating humidity escaping from the kitchen one way or another.

But yes, I need to think of other ways of controlling the RH. Hopefully in a month we'll simply be opening windows again. The HR25H is not doing all I'd hoped, which is not its fault, and really I should probably have at least two or three the trickle rate to control upstairs at night with ~0.25ACH.

BTW, I overstated the HR25H extract rate in trickle mode: it's 15.7m^3/h according to their data. So nearer 0.1ACH. In fact the (noisy) boost mode gets closer to the 0.3ACH discussed.

Maybe we could contemplate another in the kitchen itself when we do a refurb (and get rid of the gas cooker for which we need permanent vent holes in the wall right now), or just a monitor that would flash a light suggesting to open the kitchen window if it gets too steamy and hot in there. Dunno.

But the one fan we have is annoying my SO already!

Maybe in the interim we could leave a bedroom window open a crack to take advantage of the excess extract volume and draw the humid air out that way?

Rgds

Damon

Entirely possible, but we do have scads of condensation on the (2G) windows, so there are multiple lines of evidence that RH *is* probably too high.

Rgds

Damon

Yes, indeed, but at a few degrees higher inside, and a Q10=2 rule of thumb for RH as well as my uni mol-biol reactions, we *should* be able to stay well below I'd have thought.

BTW, just ran across this as possible upgrade to my SheevaPlug or low power monitoring server (with built-in diagnostic display) for you and I:

http://aseigo.blogspot.com/2012/01/reveal.html

Rgds

Damon

I've been playing with UNIX and its friends for more than 25 years and don't expect to know everything about it, indeed I am very much still learning but keeping to a subset that I understand. OWFS widened that a little bit for me!

*nix has been around for many many moons and was not designed with massive user-friendliness in mind then, on machines with orders or magnitude less resources to expend on hand-holding than now...

So, no, all you are missing, most likely, is practice.

Rgds

Damon

Could be that the outside humidity has played a large part.
Ignore the 'Hour of Day' 0=14:00pm on the 31-01-2012

Read this and weep

Being satisfied that there is no condensation risk within my loft after the insulation, (been a year now), it was time to move the sensors.
As the bathroom fan had packed up, this was the ideal time to 'test' the bathroom.
I stuck the sensors at the top of the door frame, one on the landing side and the other on the bathroom side. First day the fan was not operational, after that it was fixed (just a cheap in-line one that hangs in the loft, much quieter than the ceiling mounted one, bargain at 18 quid).

What amazed me was that the bathroom (that has no windows or external wall) has a slightly lower mean temperature. Not sure of this is caused by the cold water in the cistern or cold air blowing in via the extractor. Not much in it and could just be down to the sensors.

So here is the data:

Location,Mean /C,Mode /RH%
Landing Temp,19.1,19.0
Bathroom Temperature,18.8,19.0
Landing Humidity,53.8,56.0
Bathroom Humidity,58.0,62.0

And two charts. Not once did it get to RH100%. Mirror gets a bit misty, cistern gets droplets on it, but that is about it.

When I get time I shall have a look at the correlation between inside and outside humidity and see if that play a more important role than internal temperature variation, always a problem teasing out what is happening when there are multi-variables.