[Greenbuilding] ERV's

[Ward Edwards]

In my house I have radiant infloor heat in the lower level and radiators 
in the upper level, so for the HRV I had to install dedicated 6" 
ductwork for the HRV.  I have stale air intakes in the 1 1/2 bathrooms 
and in the kitchen.  I have fresh air outlets in the bedrooms, living 
room and library.  The HRV has sufficient power at low speed to do 
sufficient air changes that the humidity in the house is controlled. 
Depending on how your ductwork is laid out, your ERV should be able to 
move sufficient air to work.  The only way is to try it.

The Lifebreath system I have has a controller built into the unit that 
can be set for 5 different fan speeds and has the option of running on a 
  20 on/40 off cycle or run continuously.  It also has a setting where 
it will come on at a certain humidity level, but that appears to only 
run on the top speed, which I find quite noisy (the low level can barely 
be heard).

If you system will only move enough air with the air handler fan 
running, you should be able to add a control that would run the ERV when 
the switch for the fan is on.  You might even have a 120V switched 
output on the air handler.  If you have a relay contact available, you 
could use something like a zone control like the Taco SR501, which is 
basically a system that has a low voltage circuit on one side and a 120V 
circuit on the other side of a relay, so that a low voltage switch (such 
as a thermostat or fan switch) can be used to control a 120V device 
(such as the ERV).

Hope this helps,
Ward Edwards
ward at buildgreen.ca

sat jiwan ikle-khalsa wrote:
> To GB list,
> A few questions about HRV/ERV operation (and obligations of the 
> installer)....
> 
snip
> (Anyone else have experience using an ERV without needing to run a whole 
> house air handler? and/or with primary heat being a wood/corn stove or 
> passive solar?)
> 
snip

> I assume that 
> there's no sense running the ERV without running the air handler, 
> otherwise I'd just be filling my return duct with fresh air, but the 
> output of the ERV would not be sufficient to move that air all the way 
> to the basement and back out to the supply registers.
> 
snip
> I think someone on this list mentioned having some kind of 
> timer/interval for running their ERV. (not sure if it was Ward).  Could 
> you or someone tell me more about that? (any special controls needed? 
> how to tie in with forced air ducts air handler?)
> 
> note: we live outside of Washington DC. and have moderate heating and 
> cooling loads. (not so much cooling for us since we choose to mostly 
> sweat out the summer).
> 
> thanks,
> -sat jiwan
>