Re: [mh] HAI RC-80 question

[Marc M. <ma...@me...>]

[list added with context]

On Sun, Jun 21, 2009 at 03:39:08PM -0500, Joel Davidson wrote:
> > >Thanks a lot for your explanations on the thermostat. I ended up getting a     
> > >couple and I'm working on setting up the second one.                           
> > >                                                                               
> > >I had a question about that: my 2nd thermostat only needs to activate the      
> > >furnace but does not need to send the 'fan' signal.  I was hoping to reuse     
> > >that 'fan' line separately from the heat/cool lines to trigger a booster fan   
> > >in another room.                                                               
> > >                                                                               
> > >Do you know if the RC-80 can be made to send heat/cool events without          
> > >triggering the fan line, and whether I can then activate the fan line          
> > >separately from heat and cool (saving me from buying a 3rd thermostat just     
> > >for the booster fan control). 
> >>
> >>Interesting question.  Your best bet would be to contact HAI and ask
> >>them, or set up a thermostat and try it.
> >>
> >>My understanding of how my forced air hvac system works (and I may well
> >>be wrong), is that in heat mode the furnace controls the fan operation,
> >>as it lets the furnace heat up a bit before the fan comes on to prevent
> >>the system from blowing cold air.  For a/c, the fan gets turned on when
> >>the system calls for a/c to prevent the evaporator coils from freezing
> >>up.
> >>
> >>I don't know if the fan line gets activated when the thermostat calls
> >>for heat though.  If it doesn't then you could theoretically use the
> >>fan line as you want, as you can control fan mode via the serial i/f.
> >>
> >>If you can wait until late October, I can do a little testing here, but
> >>it's 100 degrees in Austin right now and there's no way I'm gonna turn
> >>on my heat!
> >
> >Understood, thanks for the info.
> >The install is going to be soon since I need it for boosting AC, so I guess
> >I'll see how it works.
> 
>   Let me know.  I need to install a booster fan for my home theater, and
>   haven't yet decided how to control it.  Where did you get your booster
>   fan?
 
I'm having an installer come over to put a $50 dual zone board for my
master/slave zone system. I could have done it with mh and the computer, but
the slave system is wired so that the RC-80 doesn't get any power at all,
even passively, so it turned out to be simpler to put a dual zone board.
The installer will look where my ducts are for the living room and what kind
of booster fan I need.

I case I can't use the RC-80 to control the fan, I may just get a manual
switch.
 
Marc
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