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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 23rd 2011
     
    Is it silent in the wee hours?
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 23rd 2011 edited
     
    Pretty much so. Considering that we used to live with a bedroom full of industrial-grade Sun servers churning away for my Internet business, I don't think we'll have a problem.

    I have turned the 'boost' threshold right up to avoid boost mode coming on (quite loud) overnight even when external RH is very high like last night.

    Rgds

    Damon
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 23rd 2011
     
    Sun Servers in the bedroom, all very worrying :cool:

    You going to stick a couple of iButtons on it and see what they say when it is all settled, now I am happy that I don't have a condensation risk up in the loft (and I intend to make it prettier up there soon) I could lend you the ones I have been using up there, get the RH as well, especially if you put them on 60second sampling (or wire them to the reader and poll every 5 seconds)
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 23rd 2011
     
    That's an interesting idea (and kind of you), or I could at least add one to the nest of monitors in and around my boy's bedroom! (I'll be taking another set of iButton readings today, BTW.)

    Rgds

    Damon
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 23rd 2011
     
    I have a couple of little projects I want to do over the break so shall send them down when the post is back to normal. I have made my new hot box at last so shall be testing some materials to see how they perform.
    Be interesting to see how much your RH drops when it is on.
  1.  
    Posted By: DamonHDI have turned the 'boost' threshold right up to avoid boost mode coming on (quite loud) overnight even when external RH is very high like last night. Rgds Damon
    What temperature and RH% is it inside and outside these days?
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 23rd 2011
     
    Has been about 85% + outside: http://www.bbc.co.uk/weather/kt1

    And 70--85% inside rising to over 90% when a shower was being taken (and boost mode came on, as designed).

    Rgds

    Damon
  2.  
    And what's the internal and external temperatures?
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 23rd 2011 edited
     
    External ~11C, internal ~18C.

    (In bathroom right now 17C/82%RH.)

    Rgds

    Damon
  3.  
    Hi Damon, 10 degrees 85% RH outside air holds 8 grammes of moisture/m3.
    18 degree 80% RH inside air holds 16 grammes of moisture/m3 so your outside air is still much drier than your inside air.
    10 degree 86% RH outside air heated to 16 degrees coming through the heat exchanger enters the building at about 50% RH so this should easily drop the RH% inside, maybe wait for a cold frosty day when the moisture has all dropped from the air as dew and leave the doors and windows for a few hours to give the house a good drying, then heat it up.
    The houses I checked in the last forthnight were all about 18 degrees 50% RH.
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 23rd 2011
     
    And the bloody fan has just conked out entirely (after about an hour of running on boost) with the power-supply box warm to the touch.

    And V-A's tech support line has already shut.

    Rgds

    Damon
  4.  
    (Peers in guiltily for recommending a HR25H :-) My installation notes are at http://www.ccandc.org/cb/mvhr/

    Currrent numbers from mine: temp/RH measured by Oregon Scientific THGR810s
    Outside 7.4C 77%
    Inside 14.2C 60%
    Temperatures of the outlet and inlet parts of the fan grille measured with an IR themometer
    Outlet 12C
    Inlet 9C

    For what it's worth, current and historic temperature and humidity are at
    http://www.ccandc.org/cgi-bin/mvhr?START=end-35d&END=now
    I've just added standard deviation to the humidity graph hoping that it would show a narrower range of values inside compared with outside as it does for temperature. Unfortunately there's not much in it: Which would make we wonder about the benefit except that mold doesn't grow on the outside wall of the bathroom and the air is much fresher in the bathroom/utility/kitchen.
    -- Chris
    •  
      CommentAuthorDamonHD
    • CommentTimeJan 7th 2012
     
    Hi Chris!

    (Well overdue to send you an email, sorry!)

    Definitely the air *is* much fresher upstairs without having to mess around opening and shutting windows and doors, etc.

    Indeed, I'm less convinced about the humidity control aspect other than the bathroom itself, but I'll keep my eye on that.

    And I think I know what the 'conking out' problem is and hope to rectify it on Monday...

    Rgds

    Damon
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 7th 2012
     
    cbatjesmond
    I think from a quick look at your charts that the SD is only going to show you that 67% of the data is going to fall with within 1 sigma either side of your mean. Not going to tell you much really. That's the rouble of using the arithmetic mean.
    The other trouble is the arbitrary 0C on the Celsius scale can skew the numbers.
    But data is good all the same.
  5.  
    Chris - ref your issue in your notes of wanting another one in kitchen but being afraid of mess - do it from outside - much much less mess!
  6.  
    <blockquote><cite>Posted By: Gotanewlife</cite>Chris - ref your issue in your notes of wanting another one in kitchen but being afraid of mess - do it from outside - much much less mess!</blockquote>
    I'd need to find a longer bit or perhaps just a chuck extension (and preferably a stand to support it and the drill) because the the bit I had would only reach half way. And was a difficult to control by hand as it was!

    Thanks for making me think of a chuck extension: that *would* make it much more palatable ...
  7.  
    <blockquote><cite>Posted By: SteamyTea</cite></blockquote>

    The *biggest* problem is that I skyved so much A-level maths I really don't know when it makes sense to use SDs -- or how to use them properly :-)

    I'd vaguely expected to see the inside RH smoother with less variance than outside -- like the temperature. But a lot of the humidity is being generated from cooking, drying laundry, washing and the temperature changes from the CH seem to cause a lot of jitter even if there's no change in absolute humidity.

    -- Chris
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 7th 2012
     
    Have you got the raw data as a text file and I coudl have a look for you.
  8.  
    @SteamyTea


    I don't know if there's more information that can be got out of it, but thank you for offering: this is the raw RH data from the last few days from inside and outside.

    (Older data gets condensed into hourly then daily then weekly values so is less interesting).

    ETA: Hmmm even this extract has to be .ZIP-d

    Cheers
    -- Chris
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 8th 2012
     
    Chris ,could not open it, we have this trouble sometimes.
    • CommentAuthorJoiner
    • CommentTimeJan 8th 2012
     
    I also get the message that the zip file is corrupted. :confused:
    • CommentAuthordocmartin
    • CommentTimeJan 8th 2012 edited
     
    Damon,
    the solution to your problem is likely to be relevant to the malfunction of my daughter's regaVent 325DC L that I fitted just over 2 years ago. About 2 months ago she noticed that the response to boost was taking increasingly longer; eventually the exhaust fan began to cut out altogether ( the fans are controlled separately, manually ). Rega Ventilation were unable to provide a diagnosis or even confirm that the fan is protected by an overload/thermal cutout.
    When I asked them to check with the German manufacturer they replied ...."ECOFIT EC fans are protected by an auto-resetting fuse on the live circuit ..... the fuse serves 2 purposes; an auto-restart in case of lock rotor or similar, but will cut out competely for something more serious i.e. open circuit."
    The heat/x is not blocked, the air valves have been opened further and function is normal on LOW and MODERATE. I will defer phoning Rega Ventilation till you publish your findings.
    Regards, Martin
  9.  
    @SteamyTea, @Joiner: I've moved all the data:
    - XML dump from the RRDB
    - CSV extracted from ""
    to http://www.ccandc.org/cb/mvhr/data/

    I've just opened one of the XML files in Chrome which caused that tab to bloat to 1GB/RAM and 100%CPU so that's probably not a good idea! The CSVs should download nicely though.
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 8th 2012
     
    Chris, the *.csv download fine, shall have a look at them later.
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 8th 2012 edited
     
    Had a quick look and this is what it looks like once expressed as anomalies:

    ,Backyard,Bathroom
    Mean,78.2,56.7
    Count,6000,6000
    St Dev,3.9,5.2
    SE,0.1,0.1
    Skew,-0.4,-0.7
    Correlation,0.2

    Basically what it means is that there are more high readings than low ones and the high readings is where the condensation risk is.
    Taking just the Bathroom, as you are probably not worried about the outside humidity, you have a mean value of RH 56.7%, if you add one Standard Deviation (5.2%) to that and read off the chart, anything about that will be the probability of going over 62% RH. That is about 10% of the time.
    The risk of condensation happening will depend on temperature (or temperature drop more to the point). As these measurements where taken during the winter, they will show the worse case I suspect.
    What has to be done to make it more accurate is to stratify by time (may be possible to work out your personal grooming habits here) as most of the time the room is unused and probably of relatively low humidity.
    Do you have temperature readings for the same period?
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 9th 2012
     
    This is the one that shows what is happening. You can see that as the Temp rises so does the mean RH, makes sense as that is probably when the room is used. Your mean temperature in there is 14C, that is the real problem as it is very close to the dewpoint temp. You can do a quick and easy calculation of that using T(d)=T-((100-RH)/5).
    Hope it makes sense as I did it in a bit of a rush this morning before work.
  10.  
    @SteamyTea

    Excellent, thank you for that: especially for a specification (formula) I can implement :-) I've updated
    http://www.ccandc.org/cgi-bin/mvhr?START=end-1w&END=now
    to show the dewpoint. (I make that CDEF:BBdp=BackBathroom,100,BBRH,-,5,/,- if anyone's interested).

    So with my shaky theoretical understanding:
    - If the Dewpoint temperature exceeds the BackBathroom temp I'm obviously condensing.

    - If the Dewpoint temperature exceeds the BackYard temperature I'm OK while my MVHR/MHRV can swap enough heat from outgoing to incoming air to get the incoming air a) above the room's dewpoint *and* b) the dewpoint of the incoming air; after that I'm condensing. I'm thinking b) is necessary if it's very warm and damp outside (it happened in the summer when outside temperature was > inside).

    I now want to monitor the incoming temperature and humidity so I know when to turn the MVHR off because it's making things worse! :-)

    Cheers
    -- Chris
    •  
      CommentAuthorDamonHD
    • CommentTimeJan 9th 2012
     
    Well Chris, when you get that sorted I'll have one also, and we'll have built in the rough equivalent of summer bypass.

    Probably would be simpler to simply turn off when warmer outside than in.

    Rgds

    Damon
  11.  
    Probably would be simpler to simply turn off when warmer outside than in.

    But-but-but I like the idea of fresh _warm_ air coming in ... unless of course it gets cooled so much by the outbound air that it's not warm any more. Hmmm I suppose that's what windows are for!
    •  
      CommentAuthorDamonHD
    • CommentTimeJan 9th 2012
     
    Indeed, when it's not cold (ie about half the year) I intend to have windows open and fan off. Simples.

    Rgds

    Damon
   
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