Vent hot water heater into boiler vent liner


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Old 11-02-11, 10:37 AM
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Vent hot water heater into boiler vent liner

gas hot water heater: 40gal, 40k BTUs
gas boiler: 150k BTUs

Both natural draft vented.

Gas boiler has a 6" exhaust vent pipe that runs from the unit to the top of the chimney crown through the old coal furnace chimney.

I plan to get a new hot water heater. Can I "Y"-connect my hot water heater exhaust to the 6" boiler exhaust pipe somewhere before it enters the chimney, being sure to keep an incline in the pipe? (The boiler will be farthest from chimney, then HW heater, then chimney entry)

Also, my current HW heater has a 3" pipe, but I believe current codes are 4", will this still be ok to Y-connect the 4" HWH to 6" Boiler exhaust?

I want to move from my current HW exhaust location because it is not safe.

Thanks
 
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Old 11-02-11, 10:46 AM
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Hi,

From your post you have a masonary chimmney?

And currently it vents from the boiler 6" flue directly into the masonary chimmney with nothing else attached?

How high is the masonary chimney, and what is the chimmney size? 8x8, 4x4...etc

Let us know.

Mike NJ
 
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Old 11-02-11, 02:28 PM
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The chimney flue dedicated to the boiler is lined with a 6" solid stain-steel liner which connects directly to the boiler. So, from top to bottom, the 6" flue connect to the chimney crown and boiler, nothing in-between.

Not sure of chimney height off hand, but it is a 2 story single family gable-roofed house with the chimney on the non-gable side. It extends to at least the ridge-line.
 
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Old 11-02-11, 04:08 PM
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Well I have to check the code. Technically I believe a tee needs to be attached inside the masonary chimmney for condensation. But in NJ they let us slide. We connect a 6x6x4 Y and hook the hw heater to the boiler flue at the liner in the chimney.

Also you need to calculate it the liner can handle the additional BTU's.

Your best bet is to get an inspection by the township. I can look up to find specifics but there may be a lot of variables. Combustion air, appliance height, gas hook up, the codensation tee issue, chimmney height, BTU capacity...etc

For your own saftey get it inspected. You could have CO issues and be seriously injury or death can occur.





Mike NJ
 
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Old 11-03-11, 10:24 AM
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Thanks Mike.

I also live in NJ, curious what the code says. Where can I find it?

Also, how would one attach a T inside the chimney? Sounds impossible. How does that help with the condensation?

Lastly, I thought the connection had to be a Y, not T, or it doesn't matter?
 
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Old 11-03-11, 10:42 AM
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Lastly, I thought the connection had to be a Y, not T, or it doesn't matter?
Yes I posted a 6x6x4 Y as the hook up outside for the HWH. But I believe you are not allowed by code to just have the liner come directly down and out the chimmney. I believe it needs a drip type tee. And yes it can be done.

I will poke around for the code.

Mike NJ
 
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Old 11-03-11, 10:50 AM
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Thanks, I was misreading your "tee" reference as a T-joint.

I came across this guideline for venting:
http://www.mtlfab.com/media/L1238.pdf

pg 5 has the venting specs for 2+ appliances.
I measured my chimney at just over 30'.
Based on the table, for a 6" Nat-Nat combination, I can safely vent 206 btu/h. With a current combined 190 btu's (150 boiler, 40 HWH), I should be ok.

Also, the diagram shows connections outside of the chimney.

Lastly, I was a bit mistaken by saying the liner connects directly to the boiler. The 6" liner runs down the chimney, then there is a horizontal run/connection to a short vertical connection to the boiler. It is all 6" (solid pipe, not flex), so that is why I say it "runs directly to the boiler".
 
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Old 11-03-11, 11:16 AM
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Yes I could be wrong about the tee in the chimmney. Page 2 figure 4 shows the tee for double wall on an external chimmney. Again I would need to check to be sure. It would be in the National fuel gas code book. Or sign up with the NFPA and they let you view the codes for free, but they are difficult to navigate.

NFPA :: Codes & Standards

Mike NJ
 
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Old 11-15-11, 05:42 PM
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horizontal venting

Can you tell me the pros and cons of venting a ES2 boiler horizontally out of the basement? Is is noisy, will I get clouds of steam in the cold months?
 
 

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