Tankless Direct Vent intake and exhaust (common errors and misconceptions)
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- Опубликовано: 16 дек 2010
- Jim from EZtankless explain in detail the common errors and misconceptions that people (homeowners and plumbers alike) have with the intake combustion air and exhaust systems on direct vent (concentric type) gas fired tankless water heaters.
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So many amateur videos on RUclips these days from amateur contractors, but Jim is not one of them! HE KNOWS HIS STUFF!!!!!!
Jim, I've seen many videos on many subjects online, and after seeing only this one I'm convinced that yours are the absolute best. And I'm not trying to play to your ego. I'm instead trying to let you know that some of us recognize your knowledge, intellect, and expertise. Thanks for your efforts.
You the man! I’ve been questioning installation in my attic to exit my roof and watching tons of videos but you convinced me to vent out a side wall with confidence. Thank you
Great explanation, Jim! Thanks for taking the time.
This just answered every question I had and some I didn't even know that I had. Thank you.
Excellent insights and deep review of technical aspects. Thank you!
Generally speaking, the distance from the ground is called "the snow line" Simply the heater must vent where it cannot be "smothered" by drifting and/or accumulating snow. Distance from windows, doors, patios, driveways, walkways, the roof and soffit are controlled by local, state, and national codes. Consult your plumber for more information. Thank you for watching and the kind compliments. Best regards, Jim
very good video and explanation on how it works!
ALL of our direct vent heaters are horizontal wall exit only and our company limits extension distance as well. We would rather not sell you a heater if you wish to, or need to extend the parameters of the designed installation. (Other companies are not as conscientious.) With ALL gas-fired direct vent tankless heaters, the longer the intake/exhaust tract, the more difficult it is for the heater to breathe. This translates directly to loss of BTU and lower volume of hot water in RISE and GPM.
Very helpful. Exactly what I was looking for. Thank you sir!
I was impressed. This was thoughtfull and had a lot of important information. Thank you very much
Good stuff, Jim. Many thanks!
Very good advice, very well said thank you
Outstanding video! This is the clearest and most concise explanation of tank-less water heater venting that I've seen so far. Thank you!
Jim, you're the absolute best. Thank you!!
Because of condensation draining backwards into the heater and corroding the internals. Direct vent condensation is acidic. Most manufacturers now recommend the 94° elbow direct outside wall exit. They're most efficient this way, breath easier which translates to maximum BTU and this method doesn't require a complicated condensation separation, trap and draining device. It just so happens that our company was one of the very first to do this, now most do it this way. Thank you for watching.
Clear and useful, thanks!
Great advice, thank you!
Really good information! !!! Thanks
Great explanation is the best video ever
Really good video, explained well. I would further question where to place vent on outside of house, how far above ground or from the windows etc. and how many feet I can go from the unit. One video said allowable 26' with one elbow and to use a damper. I guess that depends on the town code?
Thanks for the advise!
Really good video, explained well.
Why;d I have to go thru so many videos b4 I found this one? Excellent! How high of a vent riser can I put on the unit B4 going out of the wall? I have a 2 story in the snow and was thinking about venting under the eaves. Also, I'm on a well and incoming water is very cold. Is the a way of pre-heating the water? Thanks!
Hello Mr. Wells,
Thank you for the kind compliments.
The problem with going straight up with the concentric pipe before the 94° elbow is that condensate drips back into the heater and corrodes the internal components and is the simple reason why this should not be done. After the elbow, the stainless steel pipe slopes at as slight down-angle and condensate drips outside at the exhaust exit point.
When you explore your local and/or state and Federal "code" you will find that venting under the eave is almost always prohibited because of the potential of entry of carbon monoxide into the home through the eave vents.
The difference between ground water temperature and the exiting hot water temperature is called "rise" and this number is usually a fact of geography. Northern users and those with very deep wells have much colder water and need higher levels of rise than Southern users due to the differences in these ground water temperatures. The larger the rise factor, the lower the GPM (gallons per minute) any tankless heater will produce. If you have very low ground water temperatures, it is best to purchase a heater with a higher GPM rating to overcome this temperature difference.
There are some ways to preheat incoming water. For example, with the incoming water supply passing through coils wrapped around the exterior of the sanitary drain pipes or passing along a heating duct etc. There are videos and users on RUclips who show their "MacGyver" type devices to do this preheating of the water supply.
Sincere thanks for your interest in our products.
Jim
Jim - great video. . Is it "normal" for exhaust to occasionally have a gas smell?
Jon Callaghan Hello Jon,
No, it is not normal for a gas smell and in fact this could be potentially dangerous. There are redundant safety features on all brands and models of heaters to prevent gas build-up without ignition. If you smell gas, you should be looking very closely most likely at your gas connections to your heater. A leak in your supply line is very dangerous as it is not within any heater's safety features' ability to control. If not the connections, you could perhaps have some type of leak related to the gas solenoid valves but this is extremely rare.
well explain thanks
Can you make a recommendation to me. I am converting the electric water heater on the hot dog cart I purchased to a propane tankless. Most others install on the outside of the cart, but the WH they use do not appear waterproof. Can you recommend one that would be waterproof? Or else placing it in a cabinet, how can I vent one of these small WH's? Thanks, Steve
Hi Steve,
The reasons they mount them on the outside of the food trailers usually relate to rules of gas-fired appliances. Typically the "code" states that you need 30 cubic feet of room (with no closable doors) for each 1,000 BTU of these devices. If you have a code inspection, an indoor mounted one will likely fail inspection for that reason. If you were to buy a "direct vent" model you could mount it inside as they do not use "room air" for combustion as the intake air supply is drawn-in from outside through the external eccentric pipe.
thank you for watching. Jim
hey Jim, could I install the exhaust to my existing chimney and the intake thru the wall...? so I don't have to cut two holes...?
Hi,
With concentric pipe, the answer is always no. There are redundant saftey devices built-in that understand imbalance in most units. All brands must have intake and exhaust configurations that are within the manufacturer's specifications.
Best regards, Jim
I want to install one of these units in my crawl space which does not have that much height . Is it possible to install the tankless unit horizontally with the exhaust vent also running out of the unit horizontally and out the wall?
Hello,
These do not work in any position other than upright for a number of reasons.
Primarily, the heater must be "upright" as by design, the fire is "under" the heat exchanger that has the water running through it. This heat from the fire must rise through the heat exchanger to heat this water that is inside the heat exchanger. As "heat rises" (it does not go sideways) your idea is impossible.
Thank you for your interest.
Regards
I can't vent directly out of though my side wall due to property distance regulations (can intake though). Could I just go out the sidewall, up the exterior of the house and then to the roof? or must vertical venting be mostly plumbed inside of the house?
Hello,
The reason you cannot vent vertically is that the exhaust must run slightly downhill to drain condensate that accumulates inside the pipes; The Concentric pipe vented EZtankless heaters cannot be vented vertically. This is explained on our website and in other videos that are specific for each product.
Thank you for your interest.
helpfull video!!
can I use this vent assembly to vent the 101?
Hi,
No, this direct vent concentric exhaust will not work as the 101 is not direct vent design.
I see you have additional questions, please contact our company directly. You can find our contact information on our website
www.EZtankless.com
Regards, Jim
Awesome video, if your not a tech school teacher you should be. What about electric tankless?
Direct vent concentric exhaust do not use a damper. All of our indoor heaters are direct vent, so dampers do not apply to our indoor products (Our "outdoor" heaters are not direct vent, but we do not sell them for interior use.) There are codes that must be followed and yes there are rules about windows that can be opened and doors, as well as patios etc. (If a window cannot be opened, then the distance rule is different for example.)
Can the water input of this heater come from a water boiler that heats up from solar panels? When the day is sunny and the solar panels heat up the water tank then the gas heater will receive hot water as an input, means is not necessary to start boiling water if the incoming temperature is high....if the solar panels didn't heat up the water tank then the Gas Tankless Water Heater takes over....In theory it sounds like it works but my worries are if the Gas Heater will overheat the water if the inlet is already partially hot.Anyone?
Hello,
It depends upon the type of tankless heater. Your concept is very energy conservative, and indeed people do this.
With any "smart" tankless heater, the desired water temperature is entered into the control panel. There are intake and exit water temperature sensors that the computer uses to regulate the fire and air in the firebox. This process regulates the exit temperature of the water to make it consistent. If the water coming into the heater is almost as hot as the desired temperature setting on the control board, the heater will either not run or it will run in a very relaxed mode.
(If very hot water was introduced into the heater, it is conceivable that it may be possible to damage small components on the water inlet side of the heater as they are not designed for high temperature water. And it makes no sense to introduce water into a heater that is hotter than the desired exit temperature. If this were the case, there would be no need to have a heater. But yes, you have valid points. Perhaps with your idea, it would be wise to have a way to use your solar-heated water directly, or if need be, set-up the system so that you could open a valve to divert the water through the heater to raise the temperature as desired.)
The difference between intake temperature and exit temperature of the water is called "rise" - The less rise, the higher the GPM (gallons per minute) that the heater can produce.
thank you for watching our videos.
Why on EARTH is it a bad thing to draw intake air from inside the home? I keep seeing this repeated but it makes zero sense to me. Do you really think the air consumption of a tankless water heater is going to starve your home of fresh air? This seems utterly ridiculous to me.
Simply because there are codes regarding room size versus BTU on gas-fired devices. Tankless heaters often have very high BTU ratings. To meet code, our smallest "room air combustion camping and cabin" model must be in a room the size of a two car garage with no closable doors. in a super-tight dwelling, a furnace and any other gas-fired device should never fight each other for combustion air as the more powerful one can reverse-flow the exhaust causing freeze damage and/or the risk of carbon monoxide poisoning. it has nothing to do with starving your home of air, therefore, it is not utterly ridiculous.