A builder friend of mine is looking for the following: “A heat recovery system that could go full flow with no recovery to very minimal flow with full recovery. I would want the full flow to give us enough air to be a real significance in the house so that we could actually do some natural heating and cooling.”
Do any makes or models excel at this? I think the idea is that he wants to do complete nighttime exchanges relatively quickly using the filters in areas where opening the windows to accomplish that might not be the best idea, either for pollution or other reason. Thanks for any ideas.
Replies
Jim: Are you asking for the full-flow to be in a bypass mode (no heat recovery)? And the low flow to have (almost) full heat recovery?
I'm not aware of that versatile a unit, but would suggest he consider a separate big blower to do the big V w/o the HR. And then a standard HRV for typical use.
Usually the problem with DIY HRV's is in not having dealt with all the condensation and freezing issues. But for a simple "blow-a-lot-of-air-without-heat-exchange" function, that's easy. Big blower, some ductwork, a check-valve, viola! Maybe a timer switch like a suana or IR lamp uses.
I have seen such a device, can't recall the manufacturer, but it is based on the Air Exchange wheel. The wheel rotates out of the way so that something like a rooftop unit can operate in full "economizer", dumping heat and getting "free" cooling. Cost is on the order of
$6-8 K. If that doesn't nix the idea, I'll dig up some specifics.
In reality, though such a product does exist, Dave's idea is much more practical.
Tim
Thanks. I just came upon the term "economizer damper" that you also mention, and wondered why they only seemed to apply to commercial buildings. The price you list would sure be one reason!!!!
Here's one link http://www.ladwp.com/energyadvisor/EA-8.html
I'll keep looking to see if they're available on a residential scale.
Nice site Cloud. Some of that future technolgie is alredy in place. the Trane Tracer Summit System can do a lot of what the PNN is researching. Isn't it pitifull that the government will fund research that has, for the most part, already been done by the private sector?
I also get to snipe at the company I work for, thanks to that site. They just sent out a buliten to commercial customer and lifted that page in total without giving any credit fo them.
That's one of the things scientists do, repeat each others experiments just to be sure nobody made a mistake.
That is an interesting site. Thanks.
This (energy recovery on a residential level) is something I am currently investigating for my house. I have lots of commercial products available to me, but I'm not too keen on $2-3K for a good ERV. The more inexpensive ones are simpler and probably more trouble free but are less effective. Carnes, Semco, Micrometl, Air Exchange and Renewaire all make these products.
As for me, my economizer is going to be t-stat off, windows open.
As far as economizers go in commercial vs residential (w/o ERVs), the space and use dictate whether or not an economizer is useful. An interior space in a commercial building requires cooling year 'round. So for half of the year, depending on location, you have all the 55 degree or cooler air available for "free cooling". The reasons that this setup is not common or practical in a single family residence is that seldom are air handlers outside, the controls are expensive (compared to typical t-stat only) and seldom would it be of benefit (how often do you need to cool your home when 55 or less outside?).
When at all possible I like to use ERUs separate from the unit, use it as my exhaust fan and put the fresh air output into the air handler return. If the unit has an economizer, it works independent of the ERU (with temperature and humidity controls). Its only when the ERU and the unit, typically a rooftop unit, are directly coupled that the problem of the recovery wheel "in the way" becomes an issue.