Thanks, I didn’t read that through. I’ll look at it.
No, but I have “old timers” and forgot… 
P.S. It is this: https://www.manualslib.com/manual/1190735/Noritz-N-063.html
…not the N-063S that I posted 1st in that link in post #9.
Ok, here you go, it’s a single vent exhaust unit check the air combustion in the tech specs:
http://support.noritz.com/product-info.php?selected_model=N-063-NG
here is the manual (I didn’t notice you had slightly different model)
http://support.noritz.com/download.php?file=Literature%20Page/Installation%20Manual/N063%20OG%20IM.PDF&field=InstallationManual
No you don’t, you guys just use that as an excuse 
I think I may have messed up as I looked at the wrong manual as well. It is the N-063
Its LP not NG.The N-063S is a different monster. I had recommended evaluation based off of the vertical stack length, missing a condensate drain in line, being within 4’ of a door, and concerns of ventilation. It looks like the only real bust for this unit installation is that it needs clearance plate on the back of the unit for combustibles. There is also a warning in the manual about not using this unit with well water, which the client has. The deficiency written up in the report has kind of become a main topic and now I think I need to eat a little crow. I have learned a great deal from this though. I still wonder why a condensate is not required and why there is no vertical pipe limitations on this model. You could see corrosion at the top of the unit from condensation. Even though it is sealed. Over all, though acceptable practice I guess, I have concerns of a unit like this being in a bedroom. The potential for developing any type of gas or exhaust leak while sleeping is too high for me to want one of these in my bedroom. Most grateful for the lively discussion and help.
Concerns discussed still apply.
This only applies to outdoor units. What door are you referring to?
Is it a condensing unit? Do the install specs call for it? (it does not require one)
From what I read, It stated 4’ from ANY door. It is in the tiny 3x5 utility closet, so the door to the closet. I am not sure why they have that requirement.
The N-063s calls for a condensate but the N-063 does not. This is from the 063S manual
The N-063 manual does not appear to have these or the fireblock requirement.
It does say however that the air inlet must open to the outside air from the room in which the water heater is used.
I just saw where what you meant when you stated that the 4’ clearance is for an out door install and it refers to the exhaust. My bad. So technically though they could just remove the closet door and this unit would be fine where it is?
No, the unit is a non-direct venting. What this means is that the combustion air (the air needed to burn fuel and remove its combustion gases from the building) is supplied by its direct surrounding. It does not come directly from outside and go directly into the unit (via direct mechanical means). Does that make sense? if not, we have a problem! If it does… being in the bedroom utility closet… you are not allowed to draw this combustion air from the bedroom. It has to come from the outside of the utility closet room. Well, how can it get there? you have to provide it via ducts. If you remove the door, you will take it from the bedroom and we cannot do that. In fact, the door has to be self-closing and weatherstripped as discussed above. Now, as far as the 4 foot rule… this is an attempt to prevent exhaust (not combustion air), but the combustion gases… from entering back into the building. If you locate the outdoor unit right next to a window or a door and someone opens this window or door, you can be sucking in exhaust gases back into the house, not good. Thus the 4 foot rule among few others. The same applies to the exhaust vent termination. When the unit is located outdoor, the vent termination is the unit itself. If this does not make sense, well, I’m afraid you will need to start from very beginning. You need some background knowledge to understand what’s happening. This background knowledge is all explained in nachi courses included with your membership.
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Looks like you get to be right for once. Blind squirrels and all that…
Congrats!
Thanks Simon. Sorry for the painful explanation.I really do appreciate it. I understand the differences in the two types between direct and non direct, I am having a difficult time in trying to determine the two types from the manufactures description. The 063 manual calls it a
“power vented”
So when determining what type of heater you have from the manufacture, What is it you look at to determine if they don’t use the terminology of “direct - non direct”? Just the front of the unit where it is drawing the air? When I am seeing “power vented” as in the attached it make me think "mechanical " and begins to trip me up. Again thank you for your patience and help.
To understand “power vented” you need to understand “natural draft” appliance. Power vented implies there is a fan (mechanical means as oppose to natural, requiring tall vertical chimney/vent to create natural draw to expell the gases) used to exhaust the combustion gases (and draw-in air, thus the air-supply next to power vented in your image). Power vented units can typically be vented out the wall unlike natural draft. It does not mean the combustion air is drawn from outside directly via mechanical means. To determine if it’s direct or not, I check where the combustion air is taken from and how. Direct vent unit will have either 2 vents (typically in form of a round pipe), one for intake air and one for exhaust gases or single concentric (pipe within pipe). How this is described in manuals varies. You need to understand the principles, then you understand what to look for. For example… why does this non-direct unit have air inlet right on the front cover of the unit? well, that’s where it draws the combustion air. The direct units normally are fully enclosed with few small openings for heat dissipation.
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Thank you very much! Good explanation! I think I have a better understanding now. I am seeing more and more of these units in different configurations and am really trying to get a feel of safely inspecting them. The thing with all of them, is like what was mentioned above, and that is reading the correct model and manufacture manual. It has been a learning experience to me as to how differently they could be installed with the exhaust plumbing and the same type of vent diameter. I think the key is to take lots of pictures so that when you end up having to read the manual later on you can reference everything. That or maybe some inspectors pull it up on their phone right there on the spot. Thank you once again!
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I truly hope it helped… if something is still confusing (I know it can be), don’t hesitate (too many do) to ask. Better … in here than in front of your client, or worse a judge 
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Some tankless water heater can be installed with zero clearance to combustibles. The flue pipe is made to pull in the combustion air as well as expel exhaust. No fresh air needs to be supplied for this type of tankless water heater. Often a manufactured thimble should be installed to accommodate the flu penetrating the exterior wall. My only concern would be the distance from the electric panel given the panel requires 30 inches of clearance. These units are not considered direct or power vented. Those terms apply to water heaters that have a storage tank. Best practice if you have any doubt is to contact the manufacturer for installation instructions. Often these instructions may be found on the tankless water heater.
vanished before my eyes…
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Have you been exposed to CO?
Martin, can you help me understand why you think the “power vented” term applies to only water heaters with a storage tank when the manufacturer’s installation instructions call this on demand tankless water heater a “power vented model”?
See pic below.
This is for the Noritz N-063 model that the OP stated:
https://global.discourse-cdn.com/internachi/original/3X/d/0/d0034789bfd4924bdb6dbace196117d5c852dbfe.pngFuel fired tankless water heater’s have an exhaust that is powered to vent to the exterior and power assistance to bring combustible air into the unit.
Typically a “Power vent” water heater is a term used by professionals to describe a storage type water heater that uses a fan to expel the exhaust fumes. Sometimes they require combustible air from the outside through a separate PVC pipe and sometimes the combustible air is drawn from the area the water heater is stored in.
It’s very common for manufacturers to call tankless water heater a power vented water heater. In reality a true power vent hot water heater is a stored water heater with a fan assisted flue exhaust that can push the exhaust through PVC pipe a considerable distance.
Sure would be nice to see a dirt leg installed instead of an elbow on this illustration
I would contact the manufacturer about the plate being required for the rear of the unit. Generally tankless water heater‘s can be mounted directly to drywall or use a small hanger. I would be more concerned that that is category three flue pipe. There will be restrictions on vertical rise and number of elbows as this is a fan assisted flue pipe. As far as a condensate drain and the flue pipe you may need to refer to the manual for that information as well as all manufacturers vary.
The bottom line is if you do not know enough information about the water heater to feel comfortable with giving it a good inspection you may recommend that hot water heater be looked at by a professional license contractor.