# Polypropylene Boiler Venting



## markb (Jun 11, 2009)

Have anyone been using polypropylene venting on their boilers? What is your opinion? What about concentric venting? Do you run your exhaust in poly and fresh air in abs/pvc?? Are people even using it?

System 636 CPVC pricing is extremely expensive and I am looking for a less expensive way to run boiler venting. Is poly the way to go? And why?

Thanks!:thumbsup:


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## plbgbiz (Aug 27, 2010)

markb said:


> Have anyone been using polypropylene venting on their boilers? What is your opinion? What about concentric venting? Do you run your exhaust in poly and fresh air in abs/pvc?? Are people even using it? System 636 CPVC pricing is extremely expensive and I am looking for a less expensive way to run boiler venting. Is poly the way to go? And why? Thanks!:thumbsup:


Have you sought n opinion in writing from the manufacturer?


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## Greenguy (Jan 22, 2011)

The county where I live they allow you to install ABS for all venting needs, that said I normally do CPVC for my exhaust and PVC for my intake. 

When I asked the county building inspector why they allow ABS, he replied "because some manufacturers allow it"


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## plumbdrum (Nov 30, 2013)

Greenguy said:


> The county where I live they allow you to install ABS for all venting needs, that said I normally do CPVC for my exhaust and PVC for my intake. When I asked the county building inspector why they allow ABS, he replied "because some manufacturers allow it"


 Your inspector sounds clueless to me, if the manufacturer allows for PVC he cannot state that you have to use ABS unless the manufacturer states differently. I love these guys that make up their own rules. The only other way he would have any say would be a state code modification or a local ordinance.


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## Plumbus (Aug 4, 2008)

This is a Catch 22. The water heater manufacturers say use PVC or ABS solid core and the manufacturers of PVC pipe and fittings say PVC (and ABS) are not rated for condensing appliance flue usage. Guess who will be holding the bag when the stuff hits the fan and the hyenas (attorneys) start circling.


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## ShtRnsdownhill (Jan 13, 2016)

I always use stainless steel on any induced draft boiler or water heater..


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## plbgbiz (Aug 27, 2010)

plumbdrum said:


> Your inspector sounds clueless to me, if the manufacturer allows for PVC he cannot state that you have to use ABS unless the manufacturer states differently. I love these guys that make up their own rules. The only other way he would have any say would be a state code modification or a local ordinance.


He said the inspectors "allow" abs, not "state that you have to". All of the AHJ's under a given code of facts come up with their own version of truth in different areas. I have yet to see two inspectors interpret codes the same. It is always a moving target with inspectors.


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## markb (Jun 11, 2009)

plbgbiz said:


> Have you sought n opinion in writing from the manufacturer?


Went to our local trade show last week and ask our two main manufacturers "HTP and NTI boilers"

NTI states that to "make it simpler" they require all installations to be installed with CPVC piping.

HTP was very upfront to say something along the lines of:

As long as we are running radiant temps less than 150 (which is typical, especially while running our system on outdoor reset) we are in the clear. 

My biggest concern was what the boiler does during a DHW demand. If my boiler ramps up to 180 degrees, will my stack temp rise?

He said, the stack temp on a DHW demand is actually lower than what Sys 636 PVC is rated for because you are heating up cold water. Most of the boilers heat is used inside of the indirect hot water tank and very little ends up in the exhaust fumes. They are OK with PVC being used and even recommended we take the flu temperature during a call for heat to see for ourselves. 

I think it makes sense to me. What do you think?


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## plbgbiz (Aug 27, 2010)

markb said:


> ...I think it makes sense to me. What do you think?


Yes it makes sense. But without the inspector being able to reference the recommendation in writing, he may not sign off on it. By passing an inspection, the city takes on a measure of the liability if the inspector strays from the code and/or manufacturer's specs. What a rep tells you verbally matters not in a courtroom. He will be on the sidelines while the attorney for the plaintiff decides who is paying for lunch between you, the city, and the manufacturer. 

"I was at a trade show and the rep told me..." is a weak defense. Varying from the manufacturer's written specs is risky no matter how much sense it seems to make.

I'm not saying you are wrong or that it's functionally a bad idea. But as the installer in the field, you should think it over before volunteering to accept product liability.


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## plbgbiz (Aug 27, 2010)

I would be shocked if the real reason NTI chose CPVC is to "keep it simpler". That is convenient for marketing but I doubt their engineers spec'd CPVC to make things easy on everyone.


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## ShtRnsdownhill (Jan 13, 2016)

all that plastic flue pipe is great when the unit works correctly, when it doesnt and the flue temps goes up and you fill the house with poison gas from the burning plastic and kill everyone,,someone is going to take it up the a$$ in the lawsuit...and it could become criminal if you were negligent in knowing it could happen..


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## Greenguy (Jan 22, 2011)

We are actually working with our local inspectors, we hosted a sit down with the county and city inspectors so we could hash out exactly what's required for new construction jobs and water heater jobs. My employer even went so far as to buy all the guys the 2012 IPC code books so we are all on the same page. 

We deal with a lot of manufactured homes, which has there own rules separate from IPC regs.


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## plumbdrum (Nov 30, 2013)

What does the IPC have to do with venting of flue gasses?


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## Catlin987987 (Nov 12, 2010)

We use the Polypro and Centrotherm Polypropylene Venting. Its very easy to work with and looks very nice. Its inspectable because you can take it apart.


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## markb (Jun 11, 2009)

Catlin987987 said:


> We use the Polypro and Centrotherm Polypropylene Venting. Its very easy to work with and looks very nice. Its inspectable because you can take it apart.


Thanks. Do you find you need all the various fittings or 90s and 45s are enough? Our wholesaler does not stock the material and has to be shipped from the states.

Also, what do you do for fresh air? It seems silly to run poly for fresh air when pvc or abs is cheaper????


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## Catlin987987 (Nov 12, 2010)

markb said:


> Thanks. Do you find you need all the various fittings or 90s and 45s are enough? Our wholesaler does not stock the material and has to be shipped from the states.
> 
> Also, what do you do for fresh air? It seems silly to run poly for fresh air when pvc or abs is cheaper????


We run it for both, so it looks nice. We also only use on boiler jobs. Furnaces and HWT get S636 PVC. They stock most of the regular type of fittings. If they are out, we use the other brand.


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