Re: Re: Control of ventilation system

[Martin Howell <martin.howell@xxxxxxxxxxxx>]

Different strokes and all that.  The heat exchanger is a plus feature
until a long cold winter's night occurs, when the heat available to the
exchanger is more than offset by the intake of cold air into the house,
requiring additional heating to restore the normal working temperature -
I believe that the system could be shut down for the coldest hours
overnight and restarted in good time to prevent the house smelling like
a sweaty sock.  In the hot summer days, I'm not interested in a 'cooling
draught', only using the extractor in short bursts to remove the bulk of
the hot air in the house - in fact, in the summer, you really need the
system running all night to bring in cool air (heat exchanger not
present) and in the day it can largely be turned off and ventilation
provided by open windows.

I'm interested in applying a bit of common sense logic to reduce running
costs - no argument from me about the benefits of the system, I wouldn't
have a house without it, but there are times when its rather crude
on/off controls could do with a bit more sophistication.  I just wish I
knew how the damn thing works so that I can interface to it.

Martin

rb_ziggy wrote:

>--- In ukha_d@xxxxxxx, Martin Howell <martin.howell@g...> wrote:
>
>
>>I have a Villavent whole-house ventilation system, and its v good.
>>However, the controls are very on/off and manual, and I would like
to
>>apply some intelligence to it - for example: in the winter, monitor
>>outside temperature and stop the intake of air if it drops below a
>>certain temperature;
>>
>>
>
>Not sure this option is not too 'smart'.  If you switch off the
>'intake of air from outside' fans you effectively waste the feature of
>the heat exchanger.  Consider: normally cold outside air is warmed by
>the warm (damp) extract from the inside and you reclaim some of your
>expensive heating costs (thereby paying for the electicity to run the
>fans).  If you don't use this heat recovery, cold air will inevitably
>now leak into the structure to replace the extracted air, but the
>leaky air is not warmed...
>
>Also, best not to turn the whole thing off (i.e. extract + incoming)
>in the cold either.  This is when you need it most, all this actually
>achieves is a warm, wet fug and loads of condensation - especially if
>you went to the trouble of sealing the house reasonably well to allow
>the MHRV to work well.
>
>
>
>>in the summer, turn the fans on to 'boost' if the
>>temp in the house gets too high, and so on.
>>
>>
>>
>
>In Summer, it's not a bad idea to turn off the incoming air as you
>don't really need this air 'warmed'.  But this is more or less easy to
>do on a once a season basis.  Boost can be used on the extract but its
>probably (in my experience) too noisy to leave on all the time or to
>be really effective in creating a cooling draft; It's more effective
>(seriously) to open the windows (bigger area for ventilation etc...).
>
>One area where it would be really useful to automate is to put
>humidistats in the extract rooms (bathrooms) which then automatically
>switch 'boost' on and off.  This would be great as it's frankly a bit
>of a pain to go find the boost switch in (for us) the landing cupboard
>to clear the mist in the bathroom after a bath/shower.  This remains
>on the to-do list for me!
>
>
>
>>Does anyone here a) have a system like this that they have taken
>>
>>
>control
>
>
>>of, and/or b) know what the control panel signals are likely to be
so
>>that a PC could simulate 'em?
>>
>>
>
>Yes I do have one but its not controlled as such. I seriously thought
>about it but when I worked through the above, I realised that it's
>best left to do what it's designed for and to work in an 'always-on'
>mode.  I'm a great advocate of these units, wouldn't be without now as
>the air quality is better.  I'm always amazed by the gunk that
>collects on the extract filters - the incoming ones are always clean!
>
>For my system (not Villavent tho) the control signals are literally
>just switches (including the boost) so could be replaced with mains
>rated relays.  We have:
>
>- overall on / off
>- summer / winter (summer switches off the incoming fans)
>- boost (switches up the extract rate, and I suspect the inlet fan too)
>
>I've tried talking to the company, and
>
>
>>they're as much help as a chocolate teapot.
>>
>>
>>
>
>Probably 'coz it's never occurred to them to control something that
>doesn't need that degree of sophistication - different if you have
>full AC though!
>
>As you might guess my advice is to spend your time and money
>automating something really trick (that projector & screen from the
>ceiling) or adding the chiller unit to the system so you get cooled
>air in the summer. Go on, you know you want one :-)
>
>Regards
>
>Richard
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>Yahoo! Groups Links
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