HRV anyone?

ive never seen a hrv (heat recovery ventillation) used for a indoor in winter does anyone use it? if not why not? looks like a good idea to up air exchange and not spend way more in heating. imo

I don't think this is exactly what you are getting at but I exhaust heat from the grow room to the rest of the basement area with a fan and filter. Have an opening covered with a filter for a passive intake back into the grow area.



Nothing fancy for sure. The fan comes on with the lights. The grow area stays between 75 lights off up to 85 lights on without any additional heat. There is a dehumidifier in the room that provides some heat. The exhaust is blowing towards the steps going up. The intake opening is on the side with access to cooler air from under the house crawl space.

This is working so far this fall as the furnace has not had to kick on except a few mornings after lights had been out for a bit.

yeah but your way does not get very much fresh air with co2 to work with does it? i wonder if co2 depleted air recirculates with your setup

It is possible that air coming in is mix some with the exhaust. The exhaust is exiting a different direction, out of the west wall then the intake which is in the north wall. The intake is in a separate "room" which has an opening to the under house crawl area. That area is not sealed well.

I have not measured the co2 levels. I don't have a co2 monitor. So, long story short, it is possible that the air has some exhaust mixed in. Could totally eliminate that possibility with a meter or additional ducting.

Definitely something to keep in mind. Thanks

what i mean is that i dont see any intake of fresh air from outside that way is cool for veg but in flower will run short of co2

The outside air comes from the crawl space. It isn't ducted in but that crawl space is not completely sealed and has two windows to the outside plus vents. The crawl space is over half of the square footage of the house. I have made an assumption that there is adequate air exchange happening in that area but...

You are correct that I have not measured to confirm the amount of co2 present.

ah in that case you are well set. maybe adding a homemade hrv would give you 20-30% better energy efficiency but thats assuming you have everything dialed in. imo the first is light the second is co2 and third nutrition.

for anyone wandering what i mean with homemade hrv, i mean something like this https://www.loudawson.com/17884/how-to-build-air-cross-flow-heat-exchanger/

as you can see the hrv does pretty well with low temps and removes a lot of humidity. good for flower. and you can collect the condensated water and use it im sure it has awesome ph

Thanks for that info.

Spent many hours looking into this for a kinda either grow room or centralised heat distribution for my house (5 bed). The plan was to use either a HRV (cold dry in, warm dry out to house and warm dry in and cold wet outside). THe problem is that most have internal fans and using an inline fan also from a carbon filter etc might overdo the MRV fans/efficiency unless you bought a huge one or passive...not spent enough tome looking. Remember the small ones start around £1000+ with 6" intakes etc...

The other cheaper option is to use a 3-way electronic adjustable ducting system to split the extracted air. As I have yet to find a simple inline duct dehumidifier I would have the 3-way nit on 50/50 with part going outside and part going into the attic and then back down to the top of the stairs wich a small discrete mesh register (like the yanks have) that feeds the air from the room. I would pop a few humidity sensors around the stairs where the register of warm hot air is and if the humidity goes to high then the 3-way closes most the exit into the house pumping most outside...this would cost around £150+ over £1500+

Ideas

I use a HRV. Works well. I’d still like a bit more heat. I use all led. Veg and flower room are one room with a divider. Recently tied an extra fan for the veg room to HRV RH controlled, with a check valve. So if it runs the room goes negative pressure and pulls air through the HRV recovering heat. I have a couple RH and thermostat controllers set to chose HRV or dehu if it gets cool in the room. Summer I have a separate vent I open. I also open the thaw, bypass on the HRV. So I’m summer it looses all heat when running.
It’s a fine balance between heat and RH. I’m in Canada so winters can be -30. Dry and lots of cooling haha.
Took a bit of trial and error running the insulated vent pip up in the attic of my shop. Runs all the way to the back end and out 30’ The vent rises to make an inverted V so moisture going up runs back the the HRV. Once passed the peak it runs down and out making a huge ice stalagmite on the ground in winter. Froze off a couple times before I got it sorted. One little sag and if fills with water/ice.
I’d like to set an Arduino to do all the controlling, programming has been holding me back. Maybe one day.

If you want heat then why vent at all? Use a dehumidifier, if it ends up getting too warm put an in-line fan on a thermostat. Co2 on a controller set to 400 will last an entire grow.

nxsov180db said:

If you want heat then why vent at all? Use a dehumidifier, if it ends up getting too warm put an in-line fan on a thermostat. Co2 on a controller set to 400 will last an entire grow.

Click to expand...

You're probably right, bang for your buck wise.


You can't really beat a fresh & constant incoming air supply though, right?! HRV/ERVs (depending on your climate, humidity, etc) are proven to lower the levels of pretty much anything and everything that could be floating around, or even off gassing (lol) or whatever inside your home. Including PM spores, and a host of other allergens & stuff that build up with stale/recycled air. Well designed units are good at recapturing a huge amount of the heat (or even the cold AC air, and vice versa) that would be lost if venting without any recovery unit, making it a very worthwhile investment towards clean air and overall quality of life! As far as using them for growroom/greenhouses, there isn't much info out there though. Lots of DIY guides though, which is cool.

While they are technically designed to lower c02 levels in a tightly sealed home, they still keep supplying it at all times, at the natural healthy levels at least. Just like being outside. Probably around the same 420? or whatever level, but for free without needing a bottle Well, not really free though, because the commercial units are quite expensive to initially buy and install, and do require maintenance throughout the year. Like installing new filters/cleanings every few months. I guess you could use real HEPA filters circulating the air in a c02 suplemented sealed room instead to clean it up, but that would probably be even costlier to setup/upkeep, and still not as good overall as the fresh high quality vented in heat recovered\filtered air from outside coming in at all times..

thats what i mean ... you laid it out perfect;
now bang for the buck i would not vent and keep a window cracked
thats what im doing and they are doing fine
expect update tomorrow on my grow journal
they are beautifull

Drop That Sound said:

You're probably right, bang for your buck wise.


You can't really beat a fresh & constant incoming air supply though, right?! HRV/ERVs (depending on your climate, humidity, etc) are proven to lower the levels of pretty much anything and everything that could be floating around, or even off gassing (lol) or whatever inside your home. Including PM spores, and a host of other allergens & stuff that build up with stale/recycled air. Well designed units are good at recapturing a huge amount of the heat (or even the cold AC air, and vice versa) that would be lost if venting without any recovery unit, making it a very worthwhile investment towards clean air and overall quality of life! As far as using them for growroom/greenhouses, there isn't much info out there though. Lots of DIY guides though, which is cool.

While they are technically designed to lower c02 levels in a tightly sealed home, they still keep supplying it at all times, at the natural healthy levels at least. Just like being outside. Probably around the same 420? or whatever level, but for free without needing a bottle Well, not really free though, because the commercial units are quite expensive to initially buy and install, and do require maintenance throughout the year. Like installing new filters/cleanings every few months. I guess you could use real HEPA filters circulating the air in a c02 suplemented sealed room instead to clean it up, but that would probably be even costlier to setup/upkeep, and still not as good overall as the fresh high quality vented in heat recovered\filtered air from outside coming in at all times..

Click to expand...

Yeah fresh air constant supply is nice to keep mold and mildew at bay.. I actually tried recirculating hepa filters for my sealed room and they didn't help, only thing that stopped the pm and budrot was an AirRos machine that cost over 4 grand lol.

Pretty sure turpman has something of a home lab setup, and I can only imagine he benefits (at least psychologically knowing?) from the HRV system, by not having as high of spore loads and whatnot while working with tissue and other cultures, etc.. I know hospitals and other facilities do.

I know I feel kinda claustrophobic in sealed rooms for some reason, just like if I drive with all the windows up. Its like I can smell the stuffy carbon smelling air too, and can't be in there for long. Just something about it gets me. Probably because one of my old bosses would force me to work in a shop with propane torch heaters all winter, keeping the door/window closed to keep the work peices warm. I swear it would get like 20k+ ppms of c02, and I would get light headed af..

Anyway, I'm hoping setting up some DIY recovery units can somehow fix all those problems, and help me grow the cleanest produce as possible in my rooms while saving loads on heat during the winters.

I keep skipping around on the designs I want to make.. from using longer sections of 3 inch pvc with inner soda pop cans glued together into stacks, to stacking plates of plastic corroplast (or aluminum beer cans squished on a press into plates) as the 2 way crossflow cores.. Dual cores is even better!.

Now I'm looking into making my own rotary enthalpy like wheel than spins with a little motor\belt drive, mixing the heat between the 2 air streams instead of through the stacked plate cores. Rotary HRVs are more like 90% efficient? They are so simple in designtoo, and its a crime how much they charge for the better technology like they do, lol. With cheap arduino chips, you can program everything, including how fast the wheel spins. Dial it all in perfectly.

I just need to score a few sheets of this aluminum sandwich paneling, and rip it into 2-3 inch strips right on my regular woodworking table saw.. to wrap around a bearing one layer at a time, into a big wheel. Then use a belt with a motor inside a frame to spin it. How hard can it be? Why does it cost 10s of thousand to buy a commercial unit like that ^? lol.

Trying to figure out which type of DIY HRV/ERV core to build. It's hard when all the best youtube vids on the subject are in Russian, lol.

I could pickup a 50' roll of aluminum flashing that is 10" wide for around $40, and cut it into 60x 10x10" sheets. Then stack them about an 1\8" apart with strips of double sided foam tape. That would make a pretty good size core! As big as the commercial house size HRV units come with. 2 of them in a dual core configuration would be very efficient! Use rigid foam to make the housing for the unit.



Or, somehow corrugate the flashing with a roller system or press, and roll it up into a rotary type of core, like in the top video above. I think that would work better and be cheaper than buying bundles of thin aluminum tubing..



This would be nice tool to have, so I could run a whole roll of flashing in no time.

I'll probably have to resort to using some kind of temporary makeshift press to form it with instead, doing one section at a time along the roll if I want to corrugate it like that.


Stacked plate cross flow core with the sheets cut up into panels would be way easier, but I know rotary wheel types are more efficient..

Decisions...