DIY Heat Recovery Ventilator ?

[Lance]

Matt's right. Any cold air brought inside and heated is consuming energy.

[bassman]

Well there ya go then, won't work properly. Thanks everyone, time to re-think.

As well as humidity control I would like fresh air circulating above the water.

[mark]

How much air you talking of moving?

If your talking to move the moisture evapourated would think you could get by with a reality low CFM. Just do what your thinking (vent hole opposite to let in the room air in) and could use a small in-line fan such Princess Auto carries to boost furnace ducts or fab something up with a small muffin fan.

[bassman]

Originally Posted by mark

How much air you talking of moving?

If your talking to move the moisture evapourated would think you could get by with a reality low CFM. Just do what your thinking (vent hole opposite to let in the room air in) and could use a small in-line fan such Princess Auto carries to boost furnace ducts or fab something up with a small muffin fan.

That is exactly what I am talking about, almost a whisper of air would do it I think.

[rdnicolas]

Originally Posted by bassman

That is exactly what I am talking about, almost a whisper of air would do it I think.

There are two general ways to remove mosture from air.
1) Use a dessicant dehumidifier
This uses a mosture absorbant silica gel to trap moisture from air
2) A (direct Expansion) DX Dehumidifier.
This has a refrigeration cycle that cools a heat exchanger below the dewpoint temperature of the air passing through it. The mosture will condense on the surface (like water condesning on a cold pint of beer) and drop out of the air.

Using a dehumidifier is probably the best way to reduce humidity without having to worry about heating transfered air from the outside. If you wanted to build something from scratch, you can build a glycol run around loop to run during the cooler days, however it wouldn't be effective during the summer (but your air transfer from outside idea might work in in its place)

[bassman]

Originally Posted by rdnicolas

There are two general ways to remove mosture from air.
1) Use a dessicant dehumidifier
This uses a mosture absorbant silica gel to trap moisture from air
2) A (direct Expansion) DX Dehumidifier.
This has a refrigeration cycle that cools a heat exchanger below the dewpoint temperature of the air passing through it. The mosture will condense on the surface (like water condesning on a cold pint of beer) and drop out of the air.

Using a dehumidifier is probably the best way to reduce humidity without having to worry about heating transfered air from the outside. If you wanted to build something from scratch, you can build a glycol run around loop to run during the cooler days, however it wouldn't be effective during the summer (but your air transfer from outside idea might work in in its place)

I am not as concerned about removing the moisture from the air as I am in removing the moist air all together, moving it outside. I have thought about a coil, still might do something like that too.

[mark]

Little cost/benefit needs to be done also to guide your solution.

Pushing out a little air with a low wattage fan and the energy cost to heat makeup air compared to the cost of a HRV unit or running a dehumidifier etc.

When my MH are on, I use a muffin fan to blow air up from the basement through my canopy (upstairs) then it just vents to the room (no worries about moisture and have a system volume of ~200g). Figure it probably costs something less than 10 bucks a year.

Electrical cost calculator.

[rdnicolas]

Originally Posted by bassman

I am not as concerned about removing the moisture from the air as I am in removing the moist air all together, moving it outside. I have thought about a coil, still might do something like that too.

How cold do the winters get over there?

During the winter, the humidity may not even be an issue unless you are having condensation at your windows. In this case reducing outside air to a minimum is usually desired as it generally means more heating dollars for your wallet. For typical residential homes, the combination of outside air introduced from your furnace and the inflitration from the building envelope is sufficient for code required ouside air ventilation rates.

For many aquarium keepers that don't run carbon all the time, elevated tank odors, which become more prominant with higher humidity (I'd guess above 50%Relative Humidity) can be exhausted outside from the house.

This creates an issue with beneficial heat lost from the house. Moist air will have a higher heat capacity and exhausting this heat entirely becomes a huge energy waste as the air exhausted outside will be replaced with cold -30degree air entering your house which will need to be heated by your furnace.

Enter the HRV. The Heat recovery ventilator is designed to recoup some of this otherwise lost heat energy by crossing (counterflow) the exhausted and replacement airflows with eachother. During the summer, your temperatures in the house will typically be hotter than outside unless you have inhome air conditioning. This makes the HRV useless, thats why there is a bypass to prevent the two airstreams from crossing during these conditions.

So why the long winded text?

If odours (interior air quality) is your only concern than you have two choices run carbon or exhaust the odor. If you are going to exhaust, then you will benefit from an HRV during the winter but likely not in the summer as you'd probably have to run it in bypass.

If humidity is your only concern, get a dehumidifier for the summer use, and check if mosture is even a concern during winter. Unless you are getting condensation or frosting inside your windows or walls (usually occurs at RH greater than 25-30%) you don't have to run the dehumidifer during winter.

Hope this helps

Reggie

[ElGuappo]

If this is on an outside wall could you not run a 2" pvc pipe from inside your canopy throu the wall and out side. this would not allow any air into your house and alow the humiditty to go out. all it would need is a small fan for coaxing the humid air outside, and some sort of valve (butterfly/ball) to close this up in the winter.

[bassman]

Yes that is pretty much how I envisioned it, it won't need much movement at all.