We are building a 4000SF SIP home in mild climate {Southern California}.

My understanding is:

One should do an entire air  exhange 8 times per day.{?}

On rainy/humid days you may want to reduce the exchanges{?}

RenewAire EV200 is 85% efficient consuming 157Watts

Smaller than 8" ducting may increase noise{?}

Location of return and exit duct {?} should not be in seating areas{?}

Any thoughts or anyone that is living in a SIP home with an  ERV unit{?}

Do you use the 30 ~50 minute bathroom timer control? I was wondering how that would effect local codes that state we have to have motion sensor controls{?}  John

John;

I have the renewAire EV-130 in my SIP home (2400 sq. ft.), but is independent from the bath fans, still having an exhaust fan in each bath.
I use the exchanger to exhaust from the laundry room and master bath areas and a fresh air supplys to the great room.
Both the exhausts  are junctioned off going from a 8" to 2- 6" to service the 2 areas cannot hear it at all.
We use a percentage timer and the unit is set for 10% or  6 minutes every hour in warm humid times. When humidity is low and it is cooler outside we will run for 24/7

I have a timer on my ERV that allows me to progam it in 1/2 hour increments throughout the day.  I think its a Leviton product.

Washington has an indoor air quality requirement that (I think) requires a minimum of 3 air exchanges a day.  Check with your code.  Then you can do the calculations, using a guestimate for the loss in the ductwork.  I figured at 150 cfm I was really getting only about 75. 

I have my timer "weighted" towards morning (showers) and evenings (cooking) and midnight (sleeping).  The timer unit is mounted right next to the toilet so that, if you wish you had turned on the bathroom fan, no problem, you can turn on the ERV for the same result.  It get used a lot because it's next to the toilet.  Much more energy efficient than turning on the big bath fan that's made to exhaust steam from the shower.

Duct noise depends on how much air you're putting through and how close the vent is to the fan motor.  I set my ERV on the slower speed (150 cfm) to reduce noise.  Because I have a small living area, it still provides enough air through 6" duct with 3 intake and 3 exhaust vents.  If it was a larger living area, I'd probably have more vents and that would reduce noise even at higher cfm rates.

One of the biggest reductions in duct noise that I did was to use several lengths of flexible insulated duct.  It comes in about a 20' length.  If you use it for a couple of 90 degree bends, instead of a sheet metal el, you stop the vibration in the duct and almost all of the fan noise that travels through the duct.  I even put a small length on the exhaust ductwork so that it's quiet in the yard.

Mark

Hey Mark

Thanks. Good to hear from someone using and ERV/HRV.. Apprecaite all your comments and time to send them ! John

Has anyone had any experience with IAQ Monitor/Controllers? I know that some of these are not very widely available, and it might take some arm-twisting to get an inspector to sign off on one, but if the monitor is sensitive and reliable enough, then it might be a very efficient means of ensuring indoor air quality.

Here is one (I don't know anything about the pricing or availability of this unit):

http://www.tongdy.com/Upload/2009311134020756.pdf

Seems like a lot of technology to handle a problem that's unlikely to occur.  If you don't use building materials that contain VOCs, how likely is it that your going to suddenly get dangerous amounts of toulene in your living space?

If you've built with safe materials, the likely indoor air quality issues are easily addressed with inexpensive technology.  A $25 modern smoke detector is set off by smoke or even dust.  A CO monitor is about the same price as a smoke detector and covers a problem more likely to occur than the sudden onset of dangerous toulene levels.  I put a CO monitor in my living space because it is over a garage (in which I don't keep toulene, etc.)  The CO monitor is mounted in an area where it can't be seen.  I just have to remember to change the batteries once a year as, unlike the smoke detector, it isn't hard wired.

Humidistats are also inexpensive.  I've found that with an ERV, they aren't required, at least for my lifestyle.  I bought one, but never installed it after monitoring my humidity levels.  The only place where my humidity ever goes over 60% is in the bath during and right after a shower.  Since there is always a person present during this event, there's no need for a separate humidistat.  Just turn on the fan/ERV.  It's not like the humidity peaks when nobody's home.

I use the bath fan while I'm in the shower.  After that, I just push the ERV timer a few times while finishing in the bathroom.  I know that it will come on a couple more times during the day and the humidity in the bath will drop back down to 40% in an hour or so(especially if I remembered to squeegee down the shower stall).

Mark

Mark, I agree, but my point (which wasn't made very eloquently) was that an arbitrary on/off schedule for an ERV can result in significant energy losses. ERVs are not capable of recovering 100% of the energy from the exhausted air. I would be surprised if they recover more than 50% of the energy, and mitigating that loss would be my concern. By only engaging the ERV when CO, CO2 or Humidity levels are above a preset limit, the actual running time for an ERV might be significantly lower than by using a brute-force-and-ignorance method of cycling it on every fifteen minutes.

And, I'm all for brute-force-and-ignorance (and am quite adept at it), but as an energy miser, I'm just suggesting that there might be a better way. Plus, you could also benefit from (at least the peace of mind) that VOCs within your living space are being monitored and evacuated as well.

Yes !
RE:"but as an energy miser, I'm just suggesting that there might be a better way."
I hate being told how to be energy efficient by Hollywood/ bloated Politians! I like the words 'energy efficient’ much more than "Green"..Reminds me of a urology joke "is that Guacamole on your pants or are you in trouble”! LOL


I like this philosophy{ energy miser}!!

Being in California {The State of 'Confusion' where the only company our governor ran was Planet Hollywood and we know what happen to that{Chapter 11}!!

Plus only 0.001% of all our tax money {The’ porkulus bailouts’} are going to small business owners like myself and perhaps 90% or us on the site!!!!}


I cannot find much reason to air change formulas on running ERV/HRVs 100%...anyone else find {NonJunk}science to support this?? John

"an arbitrary on/off schedule for an ERV can result in significant energy losses."

We must have a difference of opinion as to what constitutes a significant energy loss.  My ERV runs at 150 watts for about 6 hours per day.  That's about 5 cents per day at my rates.  The temperature loss is seldom greater than a few degrees, meaning that if I exhaust 72 degree air I bring in 68 degree air.  I then have to heat that air back up.  Again, more pennies down the drain.

If it were possible for me to meet code using a humidity, CO2, CO, toulene, butane, etc. sensor, my ERV might run 2 hours less per day.  At my cost of electricity, my savings might be as high as 3 cents per day.  My calculations show that a fancy sensor could pay for itself, based on the reduced "energy losses," in 327 years.  Just kidding, but you get my point.   I think that there has to be a better place to spend money on energy efficiency than a sensor that turns on your ERV only in toxic situations.

"ERVs are not capable of recovering 100% of the energy from the exhausted air."
 
True, but they are amazingly close, much better than I had thought before I installed mine.  I may be getting "too much" fresh air, but that's not a bad thing being that the cost is pennies.

Mark

I am in the Sacramento area and did not even install a ERV unit. 2400SF Ranch SIP. I have a 4" duct that brings in fresh air from under my porch via a small air filter and this line runs into the intake side of the air conditioner unit. Not much humidity in Sacramento and I don't think we are that much different that soCal for temps. HOT HOT HOT! We rarely run our heater in the winter and when the a/c is on the house draws in fresh air to sort of pressurize the house a little.

I also have a single inline fan that has home run routing from 5 ducts in wash, master bath etc. Each room has a 5,10,15,30 push button switch that operates the inline fan. When you turn the fan on in any room it draws air from all 5 ducts. I also have a master switch that I can program in 1/2 hour increments or all night if I want. It has worked great and doubles as a 850CFM whole house fan for cool nights when needed.

I have been in the house for 3 years and never once felt like it was too humid. You will like you SIP home........WE DO!

Hey Sled4Fun RE"Each room has a 5,10,15,30 push button switch "

Make sense !

Which manufacture supplied the push button switches? THANKS John

Mark, that's good to know. How large is your home? And, what is your local climate like? And, how much is your average utility bill?

re:"How large is your home?"

SLIGHTLY UNDER 4000 sf

"And, what is your local climate like?"

50 to 70 Degree range

"how much is your average utility bill? "

125 to $200 {Electrical} Gas 40 to $80

John, you probably don't need to worry that much about energy loss. Orange County ambient temps are generally pretty close to indoor temps. But, even for you, if a controller could just save you $0.10 per day, over 5 years that amounts to over $180. And, that assumes that energy costs don't go up over those 5 years. A $150(??) controller then doesn't seem that extravagant.

And that doesn't mean that a controller could save you 10 cents per day, but just that there could be ample reason to explore the potential. And, I haven't explored the potential, which is why I posed the question to see if anyone has any experience with IAQ controllers.

Just the bathrooms and laundry room.  The masterbath has two air intakes one in the water closet and the other next to the shower.   I though about an ERV, but in my climate I can't see paying the $$$ for one.  The switches I got from Home Depot and they were about $20.00 ea.  
The reason I went with a single fan was all my other homes had noisy fans that I always had to deal with at sometime.   This system is very quiet, exchanges the air throughout the day when in use and doubles as a whole house fan.  

I am waffling on an ERV vs. just an Octopus vent system with timers for our mild Ca. Climate . {Waffling,…perhaps I should run for congress so I don’t have to mail my taxes today ! LOL}.

I guess my concern with just a vent system would be negative pressure and a bad fireplace draft system. Thoughts {?} Thanks Dick, John

John;

exactly the problem I had with bath exhausts and my fireplace ( poor draft) but an ERV will not correct it.

Some ERVs can actually help with negative pressure issues.  Some are equiped with barometric dampers.  If you've ever seen a barometric damper on an oil fired heating system chimney, it's similar.  It's a damper that has an adjustible weight so that when there's too much draw in the chimney, the damper opens and slows down the draft.

Here's how it works in the ERV.  You set up the ERV with a manometer so that, despite the difference in duct resistance, the ERV exhausts just as much as it brings in, meaning neither a negative or positive pressure for normal conditions.  But with a barometric damper, if for some reason there is more air in than out, it senses this and corrects it. 

So here's what happens is when the ERV is running, the wood stove is on, and then somebody turns on the kitchen hood fan.  The ERV barometric damper senses a negative pressure.  It effectively shuts down the exhaust but keeps the incoming air at full speed.  Of course, this means that there is no warm air going out, which means that there's no heat exchange going on.  You lose the energy recovery, but you may save yourself a huge puff of smoke (or maybe just reduce the amount of smoke).

Also, if your kitchen fan is 800 cfm, and your ERV is 200 cfm, the most "help" you can get from your ERV is 200.  The barometric damper reduces the effect of your hood fan to 600 cfm, and that may or may not be enough to stop the stove from backdrafting, depending on how tight your structure.  If your hood fan is only 300-400, it's probably fine.  The fire may burn slower, but not backdraft.

Mark

Mark;

 

do you have the name of one of those barometric dampered ERVs?

Chris,

I don't remember the brand name of the ERV that comes with the barometric system and I don't expect to be in my attic for awhile (it's a second home).  I'll check when I get a chance.  I think that most HVAC supply houses would have the barometric dampers to retro fit an existing system.

There is another simple fix if it's just one fan that causes you problems.  There are motorized "normally open" butterfly valve that fit in the exhaust duct of the ERV.  When you energize your hood fan, it closes the valve placed in the exhaust line of your ERV.  That gets you the same result (or maybe better) as the barometric damper, assuming your ERV is operating. 

There are also barometric switches that can be used to open and shut duct valve circuits.  My only experience with them is that I have a 1,500 watt duct heater in the fresh air duct of my ERV.  It has a barometric sensor such that the heater cannot come on unless there is air pressure in the duct.  I use it in the dead of winter and it makes certain that the intake air is warmer than the exhaust air.  It's my tiny "forced air" cheater/heater.  I don't know if these barometric switches are sensitive enough to feel the general negative pressure in the home, but a little research might come up with that info.

Mark