Flue & liner question


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Old 05-08-13, 08:53 AM
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Flue & liner question

I have a 100KBTU NG boiler that vents through a 8x8 flue approximately 25 feet total length from basement to top of chimney. I want to add a gas water heater to the flue. After reading posts here I probably would be wise to also install a liner to the flue to prevent damage from moisture. Will this lined flue support a 100KBTU boiler + maybe 60KBTU water heater?
 
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Old 05-10-13, 06:52 PM
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Did I ask a stupid or non-DIY question? Please tell me b4 I ask elsewhere...
 
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Old 05-10-13, 08:43 PM
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Just want you to know I read it, but don't have the expertise to answer.

best
Bud
 
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Old 05-11-13, 06:41 AM
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I also have read it and cannot advise. I do know that in most cases, each appliance should have its own vent, and each vent should be steel.

I will see if I can get a HVAC mod to drop by. Hold tight.
 
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Old 05-11-13, 07:45 AM
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The are charts out there in the gas code. From what I read it would seem a 6" liner would be needed.

60k water heater? Could you explain?

Also is the 100k boiler a high eff?

Any appliances induced draft?

 
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Old 05-13-13, 12:23 PM
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60k water heater? Could you explain?

Also is the 100k boiler a high eff?

Any appliances induced draft?
Worst-case, for a fast recovery model. Just off the cuff number.

No--20 years old (guess).

No--prefer simple old fashioned appliances in this case.

So this does look do-able?
On a straight flue would I be looking at flexible liner or installing sections of rigid?
I've only done this kind of thing once before when I installed a gas "woodstove" using a Duravent kit up a chimney. Wasn't difficult at all.
 
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Old 05-13-13, 12:30 PM
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If indeed 6" just streach out the flex liner and send it down the chimney. Make a hole big ebough for when you come back out of the chimney with a nice bend. No kinks.

Come out about 2 ft then add a 6x5x4 Y.

5" to the boiler??? ( Is the boiler 5")
6" to the liner
4" to the water heater ( Code) Turn the Y down on a 45 degree angle)

And the proper rain drip and cap on the top. Use high temp silicone to seal.....
 
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Old 05-13-13, 08:46 PM
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That raises a question. A boiler is short...the hole for the flue is lower than a water heater height. Will I need to punch a new hole through the wall into chimney?
 
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Old 05-13-13, 11:07 PM
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Get a low boy water heater......... Or yes make the hole higher....
 
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Old 05-14-13, 09:28 AM
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Thanks Mike.
Can I leave the boiler connection as is and punch the heater exhaust in above it (I think I know the answer to this...)

Raising the opening does have a plus in my case: There's no "drip leg" below the point where the boiler enters the flue. When I pull off the elbow I see dirt & a couple small rocks right at the bottom of the pipe/flue connection. If I cap this off and put a 2nd hole up higher I would then have a "clean-out" of sorts. Good idea or bad?

Up to this point I was planning to connect the heater to an unused 3rd flue in my chimney. Until a friend told me that the no. 3 flue is often a "dummy", sealed off with cement. I went up on the roof and he was right--the flue is filled.
 
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Old 05-14-13, 11:01 AM
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Can I leave the boiler connection as is and punch the heater exhaust in above it (I think I know the answer to this...)

No not on a liner. If the masonry chimney was used then you need to. I believe the boiler and HWH need to be separated by 6" height difference... May be wrong with that measurement...just going by memory. That code only changed a few years ago here in NJ. They used to be allowed to be tied in at the same height.

If I cap this off and put a 2nd hole up higher I would then have a "clean-out" of sorts. Good idea or bad?
Good idea but it will not be needed with the liner.

You need to check your local code for chimney lining. NJ is funny with things. I believe technically a tee needs to be installed in the chimney. We get away with it here because many inspectors dont care and sign off on it.

Call the township and ask if the liner can come right out the chimney....
 
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Old 05-15-13, 09:36 AM
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I'm tempted to punch that 2nd exhaust into the masonry flue above the boiler and call it good--but I noticed a lot of built-up efflorescence on the chimney stucco in the corner that has the boiler flue so my assumption is I may have a leaky flue. I think a liner is good insurance and probably would cost me less to DIY the install than to have a chimney sweep come out & inspect (and probably confirm the need).
 
 

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