Is anyone familiar with direct vent water heaters? I am most interested in the vent code. Performing a basement remodel and need to relocate the water heater from the center of the house to the north east corner. Will also be installing a direct vent furnace for the same reason.
Also, is there one brand recommended over another? Have an AO Smith now. Seems to be a recommended brand.
Thanks.
Replies
I've installed a number of direct-vent HWHs but always within a few inches of an exterior wall. Ones without an electric fan. All air movement is convective and through a tube-in-tube exhaust/intake pipe.
There are higher-effiency units (if you don't factor in the cost of the electricity) that use a fan. Some get enough heat out of the flue gases that you can run PVC ductwork to exhaust it. And run it considerable distances to daylight it.
Code? Read the instructions on the unit. That will have allowable duct lengths, sizes, materials, slope, etc. Yes, code is nice, but the manufacturer's instructions are more critical to follow.
Code comes in, among other ways, with where you can exhaust the flue. The roof is fine. But on a vertical wall, you must be 10 feet (???) from an air intake and ??? feet from operable window. Anyone remember?
I just recently put in a Bosch 250SX (natural gas). It's a nice unit. It has a wireless remote you can use to set the water temperature. It was the only one I could find with a wireless remote (and you can use upto 6 remotes for one unit). It is also sealed combustion (it requires a lot of air).
At any rate, venting requirements come from the manufacturer. You can see Bosch's at http://www.controlledenergy.com/html/tech/250sxmanuals.html
I squezzed every inch out of the installation that I could. My vent pipe runs about 22 ft with one elbow, which puts me at 24.5 ft. Maximum vent run on this unit is 26 ft. You also have to pitch the vent run 1/4" on the foot (towards the unit) if the horizontal run is > 5 ft. You need to be 3 ft from a window opening. There are many other little nit picky requirements.
There is also a minimum vent run which doesn't make any sense to me. It might a left over requirement from non power vented units, but I can't see why a power vent would need a certain length of pipe.
MERC.
>>There is also a minimum vent run which doesn't make any sense to me. It might a left over requirement from non power vented units, but I can't see why a power vent would need a certain length of pipe.I was taught in my combustion ffiency class that a minimum length is necessary to make sure the flue gases aren't moving too fast and thus the combustion air isn't moving too fast into and through the flame, but I don't know if that is right.It does make some sense, though,, from a combuyustion effiency point of viewI don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
Each water heater model will be different. If you follow the directions, it will comply with the national codes.
Bill