Could someone explain when you might use a power vent water heater rather than a direct vent one (and vise versa) and what are the advantages/disadvantages of each. While you’re at it could you explain the requirements (combustion air and venting) for each. It seems that one disadvantage of power vents is that they are extremeley noisy, how do direct vents compare?
I have tried to find info on the web about each but I can’t seem to find anything that breaks it down in laymans terms, any suggested further reading?
thanks
Replies
Here in Michigan power vents are now required in a basement, not sure why but the plumbers enjoy the added markup dollars that it brings.
I haven't heard that Power Vents were required in Michigan. Must be a fairly new code.
I built a house a few weeks ago that had a direct vent in the basement, the house passed inspection for occupancy with it. Thoughts determine what you want,Action determines what you get
i've sen lots of both i older and new homes, a power vent doesnt require a chimney o course just a abs vent pipe to the outside wall. however the heater wont work during a power outage whereas regular vented pilotlight equipped heaters will
The no chimney needed (just a sidewall pvc vent) can save installation problems and labor, sometimes enough savings to make them make economic sense.
The powervent heaters I have seen have higher efficiency ratings too.
I always thought the power vent models were safer - Less chance that they could backdraft.
I'm also under the impression that they're generally higher in efficiency than the kind with the metal chimney. But I don't know that for a fact.
I don't know much about this - just discussing...
I thought direct vent HWHs didn't have the problem of backdrafting?
What do you know about this?
Power vent models usually have higher efficiency ratings because you don't have as much heat loss from natural draft passing through your heater.
Better yet is power vent with sealed combustion, where the combustion air is drawn from outside through a pipe ( like a high efficiency furnace).
These are also more suitable for more hazardous areas where volatile vapors may be present.
Of course, the elimination of a regular chimney is a huge advantage.
Some negatives on the power vents, 1- The up front & replacement cost of the units, Life on a power vent & standard unit are the same, 9-12 years. 2-Location for installation, the units normally vent though a side wall not the roof, with the side wall venting you have to avoid & stay away from windows, doors, overhangs, gas meters, fresh air intakes, the neighbors wife, oh wait a minute, that last one is a biblical thing. I've talked to the plumbers & they say with all the opening in todays homes, the vent location can be a challenge. I have a power vent unit in my house at my request, I wish I would have spec a standard unit.
Paul
I see no one has mentioned Direct Vent.Direct vent uses a coxial pipe with combustion air around the outside and flue dischage in the center.The water heater is seal combustion. No problem with back drafting or getting combustion air in tight hosues.They are much like direct vent gas fireplaces.IIRC the venting is very limited on distance but can be side vented..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I did'nt realize there was a direct vent like fireplaces, I thought there was only B-vent/chimney type & power vents
Diect vent, natural vent, power vent, sealed combustion chamber, automatic vent dampers etc etc etc. All have their pluses and minus' depending on if you have enough combustion air, whether it is "good" combustion air, difficulty in venting, efficiency, size, location(can't put a natural vent in a bedroom etc).
Lots of choices and probably more than I know.
roger
On the houses I have been building lately I have been having direct vent HWHs installed. I think I'm doing the future HO a service by providing a safer gas appliance that has faster recovery time than electric, and is hopefully a little less costly to operate than electric. The direct vent HWHs are a little more expensive than a standard vent or an electric HWH. I've also been going with direct vent gas fireplaces. To me, on any gas appliance, it's just wrong to draw combustion air from the interior of the home - with the probable exception of a cook top. Unvented gas fireplaces are WAY wrong - regardless of what the mfg says.
Edited 3/25/2007 11:53 am ET by Matt
"Unvented gas fireplaces are WAY wrong - "There is no such thing as an unvented gas fireplace.It is just a question of where the vent is..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Matt is probably referring to this type of appliance:
http://hearth.com/what/gaslogs.html#anchor160143
Oh - come on Bill! :-) I was hoping there was at least one little item that we might all agree on :-)
How about this one: Wood is a natural product... :-) Can I make that statement? Ever since Clinton said "I did not have SEX with that woman". things have been so blurry :-)
"Oh - come on Bill! :-) I was hoping there was at least one little item that we might all agree on :-)"You day dreaming again ;)No, there is no such thing as a ventless gas fireplace.Ones with external vents, vent to the outside.Ones without another vent, then vent into the house."How about this one: Wood is a natural product... :-) "No. Except for the support for a tree house wood used in building a house is a processed product.No more or less than cement is a processed producted gotten from the ground."To me, on any gas appliance, it's just wrong to draw combustion air from the interior of the home - with the probable exception of a cook top. "I do agree with that.When I built my house in 79 I tried to isolated the furnaces and WH in a closet with external vents for combustion air.But for several reason it did not work out and the area communicates with the rest of the house.I hope to update it with a direct vent WH and high eff (external combustion) furnace and/or heat pump.The get rid of the combustion air vents..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Edited 3/25/2007 2:51 pm by BillHartmann
If I remember, our code would have worked in your instance if you brought in combustion air to within I think 12inches of the combustion and so many inches from the floor. The part of the code where all this is in took some reading and a lot depends if the house is "air tight construction" and other stuff.Because your situation wasn't completly enclosed it would have been deemed to be drawing from the whole house which was good. Most of my work in recent years involved high effiency stuff and direct vent stuff so I never had to venture into the part of the code involving combustion air air and venting.
I was told years ago that eventually only direct appliances would be allowed though it hasn't happened yet.
I've always wondered why we can have a gas range capable of burning 80,000BTU into an unvented kitchen with flames impinging on cold sauspans which causes carbon monoxide and sooting. Yet a leak in the venting of a 38ooo btu water heater or furnace creates a major stir.
Such is life.
roger
I was perusing those the other day....looks pretty cool if it fits your layout....no stack effect, no electric, and hot water during power outages....what's not to like!