Tankless Natural Gas Hot Water Heater Ventilation Question


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Old 10-09-13, 07:41 AM
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Tankless Natural Gas Hot Water Heater Ventilation Question

Hello everyone,

I just found this forum today and this is my first post, but I think you will be seeing alot of me because this place is a FANTASTIC resource for a DYIer like myself.

That being said, I will cut to the chase. I recently acquired a tankless water heater for my house (Noritz NRC83). I read the installation manual, and I think I'm pretty much ready to go - except for a few uncertainties I have about the ventilation.

My existing water heater is gas, so I have all the necessary fittings in place, however I have one exhaust vent that goes outside - no intake.

Looking at the installation manual, there are a few options when it comes to air intake. One of them is a second pipe coming from outside, one of them is getting air from inside. They talk about getting a ''SV CONVERSION KIT'' to do this, but I suspect this may only be a 90 degree elbow.

I guess what I am saying is I would really prefer not to have to drill another hole in my foundation and go through the hassle of installing new piping, but I will if I have to. The heater will be in a fairly confined place, but I can install openings to allow for air circulation.

What do you guys think? Do you think I can get away with not putting an intake that comes from outside?

Thanks!
Nic
 
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Old 10-09-13, 08:40 AM
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Intake from outside must be installed but it is the least of your worries and probable cost to install.

My existing water heater is gas, so I have all the necessary fittings in place
Or maybe not. They use more gas than a storage WH. The existing gas line may not be able to supply enough gas to operate a tankless and may starve other appliances of needed gas. In rare cases you may even need a different gas meter. You may have to run a new line from the meter to the TWH if there are other appliances on the line. If you post the BTUs of the TWH and distance from the meter and if there are other gas appliances on the line one of the pros here can give you the size pipe you need.

I have one exhaust vent that goes outside
That will almost certainly need to be replaced. TWHs need special high temperature stainless steel vent materials.

Bottom line it may have been free but the cost of installing might be several hundred dollars and since it is used no telling how long till it breaks down. At least leave your existing heater in place as a back up.
 
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Old 10-09-13, 10:06 AM
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Ray is spot on...

That heater is 157k btu... Your tank heater is probably 40k btu. You most likely will not be able to connect to the current gas line as ray stated. Aside from starving other appliances of gas, the outcome can be draft issues with then and deadly CO released in the home.

Running a dedicated line from the meter is best.

The flue is PVC and best to get and outside air adapter.
 
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Old 10-11-13, 08:50 AM
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Thank you for your answer.

I have no other appliances that run on gas. Just my heat, furnace, and my water heater. Also, the new heater is 2 years old, and I paid 400$ for it. I dont mind paying a few extra hundred to get it installed. It's worth close to 2000$ canadian, and I am currently paying 25$ per month to rent my water heater, so the new one will pay for itself in 20 months (plus what I will save on gas).

Regarding the vent, the manual says that ''this appliance does not produce an exhaust flue temperature in excess of 149 F, and schedule 40 PVC pipe may be used as the vent material'', so I think I may be OK (I will not go forward without being 100% certain, however.

I however started getting a bit more concerned when we started talking about gas lines and the current gas line potentially not being big enough and needing to be tapped in to the meter. I'm good with my hands, I've worked with them all my life, and I am smart, but I'm starting to have a feeling doing this one by myself may be a bit more than I can handle confidently.

If it's too much of a big job for an amateur to handle, I would rather pay to have it done by a professional, because I want things done right. Especially when it comes to gas. I dont want anyone poisoned or blown up.

What do you think? If I take it step by step, is it that complicated, or should I hire someone in this case?
 
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Old 10-11-13, 03:13 PM
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I've never worked north of the 49th, but I believe that there are some strict regulations that gas piping MUST be run by a licensed gas fitter, so you could be taking some bigger chances if you fit the gas piping yourself.

Fitting gas pipes is not all that difficult really, but obviously it must be done RIGHT and in accordance with local regulations.

Best thing is to check with local building officials.
 
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Old 10-11-13, 03:20 PM
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Furnace and heater are appliances.
 
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Old 10-12-13, 10:39 AM
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Yes technically around here you aren't allowed to go to the bathroom in your own house without having a professional watching you do it. However, I think you are good as long as you respect the code. If something ever happens, the insurance adjusters will check if everything was up to code. If it isnt, tuff luck - they don't pay. This all gives me more incentive to do it right.

That being said, I've gathered some more information. The gas line that goes to the current water heater is plugged directly into the main gas line. It is 3/4'' flexible pipe, and it is approximately 25 feel long.

Regarding venting, the picture below was taken from the manual. As long as my ''utility closet'' where my old heater was has the necessary openings, I SHOULD be able to have one exhaust vent going outside, and the intake from inside. Am I correct?

Name:  indoor vent.jpg
Views: 2547
Size:  30.9 KB

I hope I'm not asking too many questions. I am new here and I am not sure what the proper ''etiquette'' is. Just want to make sure I'm doing things right!

My only other concern is that the PVC pipe that I have coming out of my house is 3 inches if I'm not mistaken, but the exhaust coming out of the heater is much larger than that (looks like 5 inches to me) - but we'll deal with that later. One thing at a time

Thank you so much for helping me out with this, guys.
 
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Old 10-15-13, 08:31 AM
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Not to bump the thread or anything, but I would really love to get an answer on this one ... :/
 
 

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