Power vent water heater question

**B&H** · 02-18-2012, 06:56 PM

Hello, newbie here. I am considering upgrading my NG water heater natural draft flue with a sealed-combustion power vent unit. I have a small ranch house with a full basement in Central New York, and recently had the NG furnace upgraded to a high-efficiency one. The only item now vented through the chimney is the water heater. I like the idea of not using indoor air for combustion.

I am concerned about the location of the vent. The location of the water heater is in the basement, and the easiest place for the vent would be out the back of the house. However, it would be below a bedroom window and not too far away from a main-level deck. The furnace is vented out the front of the house, but obviously there aren't any windows open when it's on.

What kind of exhaust smell can I expect from a PV water heater? I can vent out the side of the house, but that will require a much more involved install.

Second question is are there noise concerns from any particular brand? Anything else I should know regarding PV water heaters?

I am trying to educate myself a bit before I call the plumber.

Thanks!

**Gary Swart** · 02-19-2012, 11:34 AM

Power vent heats still draw air from the interior. Think of the vent as an exhaust. Newer power vents use 2" PVC for venting and are quite easy to install in most cases. There is no discernible odor from the vent. I vent my furnace and water heater within 2 feet of each other, and I have never had any odor. I use the GE/Rheem heater, and have had very good luck with it. The Bradford-White is another very good brand.

**Plumber111** · 02-19-2012, 11:43 AM

Look into a Direct Vent.

**B&H** · 02-19-2012, 01:06 PM

Looking at this unit:

http://www.bradfordwhite.com/images/...eets/116-B.pdf

I don't think it uses any air from the house. I am very concerned about the exhaust smell. After replacing the WH, I am going to finish the ceiling in the basement w/ drywall, so moving the vent afterwards is going to be a bigger deal than running it out the side of the house now. I just have no idea how much "stink" a NG WH makes.

**Plumber111** · 02-19-2012, 02:17 PM

Why are you insistent to use a Power Direct Vent? Measurements won't work out for a Direct Vent? Less noise and things to go wrong with a Direct Vent.

**jimbo** · 02-19-2012, 02:29 PM

There are codes governing where a vent exhaust can be located with respect to any openable door or window. Doesn't matter if you THINK the window would not be open. The install instructions and the National Fuel Gas Code, and your local building codes, all address this.

**Plumber111** · 02-19-2012, 02:47 PM

Have you considered this or something similar? http://www.bradfordwhite.com/product...1&product_id=7

That's a Direct Vent. Uses outside air for combustion and no power necessary. No fan noise.

I have not seen huge "smell" problems with properly installed NG water heaters at all. However, I do not make a concerted effort to smell their exhausts for extended periods of time regardless of efficiency.

Check the Direct Vent. Measurements have to work out though. Consult your licensed plumber.

(Now that I think about it. You shouldn't get smell at all. The combustion chamber is FVIR i.e. sealed. So any unburned inefficiency is contained within the chamber. Then the exhaust is sealed inside the intake pipe.)

**B&H** · 02-19-2012, 03:45 PM

Originally Posted by jimbo

There are codes governing where a vent exhaust can be located with respect to any openable door or window. Doesn't matter if you THINK the window would not be open. The install instructions and the National Fuel Gas Code, and your local building codes, all address this.

I realize this and quite frankly was surprised at how close both the exhaust for the furnace and for a direct-vent gas stove are to windows. I forget what the code specified, but it didn't seem to make sense (too close). They are not bothering anything because those particular windows are closed when the units are in use.

**B&H** · 02-19-2012, 04:07 PM

Plumber111,

That WH may be a perfect fit! These are things that I don't know, direct vs "power direct".

The reason that the contractor mentioned a power vent WH is because I have been fighting a backdraft situation down the chimney for a long time. Years ago, after I tightened the house up, I ended up with a major winter-time condensation problem. I traced it to the WH spilling whenever the furnace was OFF and the kitchen vent fan was on, or when both the
bath vent and clothes dryer were on together. It was impossible to find someone adept at solving this type of problem so I got creative and installed an 8" make-up air system with a duct fan and weighted damper. Whenever the 300 cfm kitchen fan was on, we turned on the 300 cfm make-up air fan, which dumped fresh air into the furnace room. When the dryer or bathroom vent fan was on, the make-up air would occur passively. Problem solved, but at a horrible price for heating efficiency.

Fast forward to today, by replacing gas appliances that burn and vent indoor air, along with a new kitchen fan with a low setting (150 cfm), I think that the chances of the house going under a negative pressure are greatly reduced. I had explained my situation to the contractor, and that's why he recommend a power vent WH. After reading about the pros and cons of a PV, and now understanding what a direct-vent WH is and that it will meet the install and code requirements (I think), looks like that's the way I'm leaning.

How does FVIR reduce exhaust vent smell?

**Plumber111** · 02-19-2012, 04:22 PM

I can't say that it will. I've honestly never ran into an odor problem with a customer in relation to their outdoor venting.

**jadnashua** · 02-19-2012, 05:00 PM

Power venting is a solution to where you can vent since it uses a fan and smaller piping to direct the exhaust where you want it...as mentioned, it still pulls combustion air in from the house.

A closed combustion device pulls it's combustion air from outside and dumps the exhaust there as well using a sealed combustion chamber.

**B&H** · 02-20-2012, 08:21 PM

Originally Posted by jadnashua

Power venting is a solution to where you can vent since it uses a fan and smaller piping to direct the exhaust where you want it...as mentioned, it still pulls combustion air in from the house.

Not sure this is true. Read the first feature in B-W heater that I linked above.

**jadnashua** · 02-21-2012, 11:10 AM

Originally Posted by B&H

Not sure this is true. Read the first feature in B-W heater that I linked above.

With a closed combustion, it is true, not sure about a direct vented unit...as to whether there are any readily available closed combustion WH, haven't looked, but there are a lot of boilers and furnaces that use it.

**Plumber111** · 02-21-2012, 01:36 PM

A Direct Vent is a "pipe inside pipe" vent system that is FVIR. (Closed Combustion Chamber) Draws through the larger vent pipe and exhausts through a smaller pipe that runs through the center of the larger vent pipe. It's one of my favorite ways to install gas-tank water heaters because everything is closed, quiet, and exhausted at one point. No makeup air needed or anything affecting it on the inside of a structure, and it's not affecting things either with it's combustion operation. Some have said you gain a certain % efficiency over a standard installation as well due to pre-heating the combustion air with the exhaust. Not sure how true that may be. Haven't looked at efficiencies in awhile. It does have limitations on distances for venting however. But it's veeery quiet. Can't hear it much, if at all.

Installed this one today....http://www.rheem.com/product/residen...izontal-option

A Power Direct Vent is fan assisted and also FVIR. At least the ones I've seen have closed combustion chambers with no vent system visible on the heater other than the intake pipe. It has more flexibility in where it can be vented. Further lengths can be ran for the intake/exhaust. Sometimes smaller PVC pipe can be used as well. The negative is that it requires power for it to operate. If you lose power, no hot water when the tank is depleted. It is much noisier. Fan kicks on when it fires. More maintenance i.e. things to go wrong.

Again though, consult your licensed plumber and/or inspection department. There are specific measurements from combustibles and windows along with local codes that often vary.

Good Luck.