Posted on 04/29/2019 12:56:12 PM PDT by ProtectOurFreedom
Does anybody have experience with "Power Direct Vent" water heaters? I need to replace our conventional natural draft water heater and am thinking about a Power Direct Vent model. These units have a sealed combustion chamber and take outside air via a PVC pipe for combustion and the send the combustion gases outdoors via another PVC pipe.
I've read that the fans and burners on PDV water heaters can make a lot of objectionable noise. The fans make noise especially when starting up and the burners can make a loud rumbling noise.
Our forced air furnace is a similar design with a sealed combustion chamber and the coaxial pipe for air inlet / flue gas discharge. I don't hear the exhaust fan or burner rumble noise from the furnace.
I need to switch to a sealed combustion water heater as part of an energy retrofit program to prevent future ice dams in the winter. We had terrible ice dams this winter (North Idaho, Climate Zone 5) leading to water getting into the walls and buckling a small part of our newly refinished floor (nothing hurts like seeing your beautiful newly refinished floor buckling!)
In looking into the problem, I've found a lot of root causes for the ice dams - inadequate attic insulation (bare ceiling sheet rock in places!), inadequate attic ventilation, no air sealing between the house and the attic, and a utility room dumping a lot of warm air into the attic which melts roof snow.
The existing water heater in the utility room is installed per code and has two combustion (fresh) air inlets, one in the ceiling (communicates to the attic for air) and one in the floor (communicates to the crawl space for air). This creates a perfect convection path where cold crawl space air enters the utility room, is heated to 50F to 70F, and then flows into the attic where the warm air melts the snow leading to the ice dams. By switching to a Power Direct Vent water heater, I can close off the floor and ceiling vents and stop all the heat in the utility / mechanical room from flowing into the attic.
But these Power Direct Vent water heaters are expensive and I'm concerned about the possible noise problems.
The energy savings will never pay for this upgrade, but it's really important to stop the ice dam problem.
Tankless is a great way to go.
Tankless is a great way to go.
Might be a good idea to start conditioning yourself to ONLY having cold water just in case there are enough criminal voting actions that the demoncrats win and they implement their green policy...
Whatever you choose, do NOT buy from a big box retailer. Suggest you have a local plumber make a recommendation and have him install it.
Ours recommended a Rheem unit. Prefer tank type since it’s a cheap way to store 60 gallons of water in case the water goes out.
My third and hopefully last edition. The thing is great, not noisy, hope it lasts 20 years!
Two important points:
1. The attic should be totally sealed off from the rest of the house. You don’t want any air from the house going up there because in the winter it will condense and freeze... in fact it will go through constant freeze-thaw cycles and that’s bad news for the integrity and life of the roof lumber. Here’s an extreme case of what can go wrong.... A few years ago, there was a report of a house in Saskatchewan that had a lot of moist air leaking into the attic. The owner was in bed one night when a massive amount of ice came crashing down through his ceiling.
2. Follow the suggestion of a number of other posters here and go with a tankless on-demand unit. One possible caveat with this is that you will likely also need to also install an iron filter if your water has high levels.... I’m assuming that you already have a water softener unless you are lucky enough to live somewhere where the water hardness levels are so low you don’t need one. Water heaters (and especially tankless ones) don’t like high hardness and iron).
However, if you don’t want to go tankless for some reason, you really should go for the direct vent and in fact, in some locations you can’t even buy a ‘conventional one’ anymore. In your case if it’s an older house, the place may leak enough that it doesn’t matter but if the house was built very tight, there is always a possibility that insufficient fresh air is coming in to support the combustion of the water heater when it comes on. This can especially be a concern when there are other points of exhaust simultaneously running in the house such as a kitchen exhaust fan. Let me explain further... let’s assume that you have a conventional old style water heater and you live in a tight house and the kitchen exhaust fan is running. At this point, the house goes under slightly negative pressure and this means that air will be trying to leak into it from any location it can. And what’s the most likely location where it leaks in? Yup... down the flue for the hot water heater. This means that flue gases from the water heater could be exhausting inside your house. It is not unheard of for homes to have high carbon monoxide readings as a result and although I don’t have data on this, it probably has killed somebody somewhere... or certainly made folks very sick since CO is not something to trifle with. Having a direct vent water heater solves that problem.
For the record as a side note, this is a primary reason why I always carry a portable CO detector on me that fastens to my car keychain. One never knows when in somebody else’s house if somewhere along the line, someone has totally done something that can cause elevated CO levels in their homes. It’s also useful for this reason in hotels, small airplanes etc. As another side note, there are almost no jurisdictions where CO detectors are required in hotel rooms even though there are a number of cases where fatalities have occurred....
You mentioned the fan noise as a concern... I suspect that you will find this to be a non-issue but if it is, there are ways around that.....
Side issue with Power Direct Vent water heaters: My son bought a fairly new house, had relatives living in the guest room for a while - hot water disappeared. The water heater was in the basement utility room. A power cord was plugged in to an outlet box in the unfinished ceiling. Eventually figured out that the outlet box was in line for water leaking from the guest room bathroom. The moisture in the outlet box had corroded the electrical connection to prevent the exhaust fan from running, but not tripping the breaker. The outlet was an orphan making it difficult to identify to which breaker it belonged.
Do Y’All have a Ferguson’s Showroom (or other Plumbing Supply Display) if so go check them out.
Also call local Plumbers and ask them. If they won’t answer Your questions then You don’t want to deal with them anyway, so keep notes on who’s good or bad for future use.
I’ve never seen one of those type WH so can’t help Ya there, Sorry.
Good luck !
Get rid of the vent in the attic, put the money into insulating the attic space - best cure for ice dams is supposedly venting in the soffit and venting along the ridge of the roof so that there is always a path of cold air running right under the roof deck, keeping the snow on the roof from melting to begin with - a roofer might be able to help......
I bought a snow rake and started raking at least the south side of the roof after every snowfall. Ice dams are caused by sun melting the snow and then re-freezing as ice in your gutters, eventually forcing moisture under your shingles.
You don't have to rake the entire roof. Just 18 inches from the roofline does the trick. I never had ice dams again.
I think they type of water heater you’re looking at is also called a ‘condensing water heater’, and yes they pretty much take all of the heat and moisture out of the exhaust stream, leaving you with cool exhaust air mixed with somewhat acidic water, hence the need for PVC rather than metal exhaust pipes.
As to tankless, you probably already know that they require enlarging the gas service, if being put in as a retro-fit. They also have a number of other downsides, one of the biggest being that if your power is out, they simply won’t work, and you will not have any hot water. A basic natural gas tank unit [like the one causing you trouble] will work normally through an outage. Any other tank type [including electrics and condensing] will at least give you whatever water is stored for a day or so after losing power. But a tankless, whether or electric or even gas, will not give you a drop of hot water, should power go out.
Just some more to think about - as to your questions, I don’t have the experience needed to be sure, but I’d expect a condensing unit to be rather quiet, as the fan is buried in the unit and is only pushing air. It’s possible that you’re confusing the noise profile with a heat pump unit, which is electric and literally has a refrigeration system on top, used in reverse fashion [so as to dump heat into the water] - I would expect them to be quite noisy, given they’re running compressors.
Believe it. Sounds like a freight train.....
We are already doing all the cheap stuff — bringing attic insulation up to R60 and sealing the attic to living holes (pipes, wood/wood junctions, wires, etc). We are also fixing inadequate attic ventilation problems - eave / soffit vents, rafter baffles/chutes, adding necessary ridge ventilation.
This is a 6 inch hole in the utility room dumping heat right to the attic. During winter, I measured the utility room temperature at 50F to 70F, so a lot of heat is flowing up that pipe. All the time the water heater is not firing, air is flowing to the attic. It’s actually a big heat load in the attic.
I’ve thought about alternatives (electric water heater; direct vent but no power fan; getting another source of combustion air to the utility room). None of these work for various reasons. The utility room floor is about 18 inches off the garage floor and it has a 10 foot ceiling, so I’m unable to tap combustion air off of the garage and still meet code (I talked to our local building inspector on this).
I keep coming back to a power direct vent water heater. Besides, the existing water heater is getting close to the end of its life. It is now 12 years old.
The problem is I would still need a sealed combustion air unit so I can close off the fresh air connection to the attic. I see that sealed combustion on-demand tankless water heaters are made, but they are really expensive. Plus I’d probably have to increase my gas pipe size which is a big added expense.
We stuck with the conventional, can use the existing vent pipes and one less component on the water heater to be a point of failure, plus less noise. Costs less too.
Surprisingly, yes. Condensing furnaces and water heaters extract the latent heat of vaporization from the flue gas. The flue gases are down around 100F to 110F, well within the PVC operating range. Plus, the gases contain corrosive products and plastic stands up to them really well.
Our Bryant Plus 90 forced air furnace is a condensing furnace and uses PVC for air inlet and exhaust outlet. The pipe is concentric, a pipe within a pipe. These are standard installations now.
Surely you're kidding.......
How do you handle dirt in the lines when they work on/repair a water line? To prevent clogging and buildup in the unit?
LOL. Yes, that's one solution. We are doing everything backward in our 60s -- we are doubling everything. Doubled our latitude going north (well, not quite double), doubled our lot size, doubled the number of stories, doubled the house square footage. We are doing it all wrong.
Guess they don’t build anything like they used to...my existing nat. gas water heater is 44 years old and going strong w/o any leaks.
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