Re: Control of ventilation system

["rb_ziggy" <richard.boreham@xxxxxxxxxxxx>]

--- 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