# Working with B-Vent pipe for WH vent



## BobN (Mar 8, 2009)

I just installed a new gas fired WH (Water Heater) to replace a 58 year old Homart 200, Sears brand, WH. Yes, it is 58 years old. I found some of the original documentation.

Yes - Believe or not, it is is a fifty eight year old WH - it is only 2 years younger than me.

I was reading through the code yesterday (hey, doesn't everyone curl up with a good drink and browse through the HVAC and plumbing codes occasionally?) and I see that a WH installed in an unheated area - attic, garage, basement - should be vented with double wall vent pipe. The WH is in the basement and I used single wall pipe when I made up the new vent.

The photo below is of the OLD WH AND PIPING (it was what had to be one of the Plumbing Jobs From Hell).

Again - THE PHOTO BELOW IS OF THE OLD WH AND PIPING.

I HAVE REMOVED THE PHOTO SO AS TO ELIMINATE THE TRAFFIC TO MY SITE TO GET THE IMAGE FILE EACH TIME SOMEONE VIEWS THIS THREAD.

The water pipes were a combination of iron, rigid copper, and flexible copper. On the left you can see where somebody plumbed to a new kitchen sink (at least 40 years ago) with flexible copper connected to iron without using a di-electric union - did di-electric unions exist that far back?

You can also see the nice kink in the lower pipe.

The rigid copper you see was installed by me about 3 years ago to replace a section of iron which was leaking.

There were five iron unions, three on water pipes and two on the gas supply, that I had to open and it took me about 20 to 30 minutes per union. Those things had not been opened for at least 40 years - probably more like 50 - and they were SOBs to get apart.

I don't think the method I used on one of them is anywhere in the "book" - after heating it several times with a propane torch and throwing cold water on it to try and thermal shock the fitting, I put a monkey wrench (not a pipe wrench, of course) on it and hit the end of the wrench with a 2lb brick hammer while I tried to hold the other side of the joint with another wrench. I had pretty much reconciled myself to replacing more of the pipe - such as the length I might break using a hammer to loosen a union - but the union turned a bit and I was able to fully open it.

I plan to brace the WH to that iron I-beam in the background. Bracing is not required here but we are close enough to the New Madrid fault that if it really lets go, we will be in for it. I figure that if the I-beam is knocked over, the fact that the WH will go with it will be a very minor concern.

Well, I digress - my question is this:

I know how to work with single wall vent pipe, certainly not as well as sheet metal worker, but enough to get the job done but how to you size B-vent pipe?

I need a vent assembly with a 90 degree elbow and two pieces of straight pipe. One to the draft hood and one to the chimney.

With single wall pipe I just get the tin snips and cut the lengths I need.

Since cutting B-vent pretty much destroys the "system" (double walled, insulated "Dewar flask" system) and the pieces are designed to be twisted into each other, how do you get the exact lengths you need for a particular installation?

Is this something to take to a sheet metal shop or can I do it with stock pieces?

Even though our ancient originally coal fired, octopus duct, gravity feed furnace, converted to gas with a Norman conversion burner, leaks a lot of heat to the basement, I still consider it an unheated area and I want to be at or beyond code with such things.

If you are wondering about the heating system, when we can afford it, we will be installing underfloor radiant heating. It will give better heating than a forced air furnace and will actually cost less than a new forced air furnace considering that all new duct work would be needed since the octopus duct work will absolutely not work with a modern forced air system. I can also save money but installing the underfloor pipping myself.

Back to the question - how do you make up a vent using b-vent without cutting pieces to length?

Any assistance will be greatly appreciated.

Bob

Take a minute to visit http://www.jonpsalmonds.net (it is not a commercial site, this is not a plug for anything, just a referral to a rather unusual site)


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## TarheelTerp (Jan 6, 2009)

BobN said:


> Any assistance will be greatly appreciated.


If you use regular 3" single wall for that one Ell and 30" of pipe?
I promise I won't ever tell anyone.


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## ben's plumbing (Oct 6, 2011)

me neither:yes::yes:


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## harleyrider (Feb 20, 2007)

40,000 is 4 inch.......50,000 is 5 inch......make sure you install a chimney liner and wye fitting if the chimney is shared.


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## BobN (Mar 8, 2009)

TarheelTerp said:


> If you use regular 3" single wall for that one Ell and 30" of pipe?
> I promise I won't ever tell anyone.


Well, problem is that a 30" piece of pipe would reach all the way through the chimney and come out the other side 

On the new WH, the vertical piece off the draft hood is about 3 1/2" to the elbow and the piece from the elbow to the chimney is right around 13".

I'd really like to use double wall for the entire assembly since I'm in a gray area as to DIYing this and I want this to be at or exceed the code. That's my reason for wanting to use double wall pipe.

Well - there's really not any "gray" to this, it should have had a permit pulled and be done by a "pro" but we were lucky to be able to get a replacement WH.

This depression (it is not a recession for us - it is a depression) has us down to poverty levels (literally) and my in-laws actually bought the WH for us.

There was no way we could afford an estimated $400 to install the WH. $400 dollars was the cheapest I could find without someone actually coming out to look at it and, if you look at the photo, you can see that just about anyone would have tacked on another hundred or more to undo the mess before even beginning to plumb in the new WH.

Another reason for using double wall pipe is that I want to increase the slope on to the chimney and to do so I'd have to make a hole higher up on the chimney and that would put the vent closer to flammable material (the floor joists) than code allows.

There is a floor joist quite near the chimney and if I slope the vent upwards more, the vent will only be about 3" or 4" from the joist.

I always do work which is at or exceeds code, not for fear of any inspector but because that's simply how I do things. I want things done properly and, more importantly, safely. When you break them all down, all codes are aimed at safety issues.

Bob


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## TarheelTerp (Jan 6, 2009)

BobN said:


> Well, problem is that a 30" piece of pipe would reach all the way through the chimney and come out the other side


tin snips. cut the (standard length) 30" piece to the lengths you need.


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## BobN (Mar 8, 2009)

harleyrider said:


> 40,000 is 4 inch.......50,000 is 5 inch......make sure you install a chimney liner and wye fitting if the chimney is shared.


Ah, yes - the chimney liner.

On the list of things to do but on hold because of monetary considerations - nice way of saying we can't afford it right now -- read my earlier reply.

I've downloaded a lot of PDFs about liners and will be reading through them and then getting the code sections to read.

One question - it seems to me (not having looked at it yet) that you will have to do a bit of tear out on the chimney to get the access you need at the bottom - is that correct? 

And -- what do you mean with the 40,000 and 50,000 being the same as 4" and 5" -- what scale are using using when you say "40,000"?


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## BobN (Mar 8, 2009)

TarheelTerp said:


> tin snips. cut the (standard length) 30" piece to the lengths you need.


Do you mean a 30" piece of single wall? I thought you ment double wall.

As I said, I have no problem working with single wall vent - cut it to length, allowing for length of male end, snap it together, nip and crimp the male end, and then put the pieces together.

My problem is with double wall pipe. I don't know how to get the correct lengths of the pieces for the full vent.


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## harleyrider (Feb 20, 2007)

BobN said:


> Well, problem is that a 30" piece of pipe would reach all the way through the chimney and come out the other side
> 
> On the new WH, the vertical piece off the draft hood is about 3 1/2" to the elbow and the piece from the elbow to the chimney is right around 13".
> 
> ...


 i wont touch a hwt for less then [email protected] $400 i AM LOSING $300


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## harleyrider (Feb 20, 2007)

BobN said:


> Ah, yes - the chimney liner.
> 
> On the list of things to do but on hold because of monetary considerations - nice way of saying we can't afford it right now -- read my earlier reply.
> 
> ...


sorry......its industry standards......BTU's (other wise known as "british thermal units" an industry standard of measuring heat or cooling)


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## Baldrick (Jan 5, 2012)

Just use adjustable b vent section. Comes in 18" and 12" pieces in my area. Slide one section into the other and adjust it to length, then 3 (supplied) screws into the joint.
On a lighter note, if you are getting $900+ dollars to install an owner supplied water heater your making damn good money.... All of about 2 to 3 hours labour and bugger all material.


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## BobN (Mar 8, 2009)

Baldrick said:


> Just use adjustable b vent section. Comes in 18" and 12" pieces in my area. Slide one section into the other and adjust it to length, then 3 (supplied) screws into the joint.
> On a lighter note, if you are getting $900+ dollars to install an owner supplied water heater your making damn good money.... All of about 2 to 3 hours labour and bugger all material.


That sounds like what I needed to know - "adjustable" sections. Thanks.

As to cost -

The WH cost right at $390 and installation was going to be about $450.

That is the price Home Depot and Lowes quoted and I called a couple of independents and asked for their average price - telling them that I would not hold them to he price after they actually looked at the situation.

I think I would have fainted if someone had said that it was going to be $900 to install, as you said, an owner supplied water heater - either faint or tell my wife that we would be heating water on the stove from now on and that she had better learn how to take a bath in a couple of gallons of water or wait for it to rain.

I am certain that once someone saw the old setup (look at the photo in my original post) they would have immediately added a couple hundred dollars to the price.

Had it not been for the iron unions that didn't want to come apart easily and the rather obvious mess things were in, it would have take less than an hour or two to put in a new WH.

But this was far from a normal swap out.

Heck, I just stood and stared at the mess for about 10 minutes before I even began to make a parts list.

There was no shutoff value on the gas supply, there was that flexible copper, without di-electrics, going to the kitchen sink, and the shutoff value on the cold water was leaking - just to name a few things that a "normal" install would not have to contend with.

Parts came to about $70 - gas and water shutoff valves, two di-electric unions, an "install kit" with flex gas and water and compression fittings, and then some 3/4" copper - but I had enough already - and perhaps some odds and ends.

I'm going to add di-electrics between the WH water connections and the flex tubing I'm using. I've had to replace too many corroded, non di-electric, unions between iron and copper and I'm not going to possibly set myself up for more problems with the WH connections.

I am assuming that the install quotes I got were for a simple "disconnect the old and move it away" and "move in the new and connect it."

This was far from being that easy. There was more than once that I thought about getting the reciprocating saw (that's a sawzall to some) and just start cutting until I came to a union which would come apart and then plumb back from there.

I said, in the original post, that the 3/4" copper in the photo was put in by me to fix a leak 2 or 3 years ago - well, when I took the di-electrics apart, they were already pretty badly clogged up. All of that old iron pipe has got to go!

Well, I'll look for adjustable sections of b-vent and see what I can come up with.

One other thing, out system does nnot have any sort of back-flow stop device of some sort, so it is not a closed system But I'm going to install an expansion tank because local code requires it with a new WH is installed - they don't care if the system is open or closed (I think the guy I talked to doesn't know that an expansion tank is only actually required on a closed system which has some sort of stop back flow valve or such)
-------------------------------
Let me close with this very off topic subject -

Do you know that you can have a heart attack and not have chest pain?

You can! You can have a fatal heart attack without any of the classic symptoms like chest pain, shortness of breath, or left arm pain.

I've had two. For the full details, go read a posting I did back in 2002 right after my first heart attack on Healthboards.com

Got some spare time? Go visit http://www.jonpsalmonds.net not a commercial site or a plug for anything, just a rather unusual site - I understand that a easier to read and better formatted version is on its way.


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## ben's plumbing (Oct 6, 2011)

Baldrick said:


> Just use adjustable b vent section. Comes in 18" and 12" pieces in my area. Slide one section into the other and adjust it to length, then 3 (supplied) screws into the joint.
> On a lighter note, if you are getting $900+ dollars to install an owner supplied water heater your making damn good money.... All of about 2 to 3 hours labour and bugger all material.


 it only takes 40 minutes to install a standard 40 gal gas heater.. :yes:


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## Baldrick (Jan 5, 2012)

Gotta pick up the tank, drain the old tank, install new tank, test operation, remove and dispose of the old tank. Work by myself so takes a little longer than 40 min.


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## how (Feb 26, 2011)

I thought bragging about how quickly one can install a HWT is for newbees. Short cuts include/rough tank treatment/ missing things like checking tank flapper valves, drip legs, earthquake strapping, leveling the tank, draining off tank debris & pipe soldering flakes to an outlet that won't get plugged by it, checking air supply & venting or just checking the house water pressure.. etc..
I think the real measuring stick should be how long the HWT that one installs... lasts.


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## ben's plumbing (Oct 6, 2011)

how said:


> I thought bragging about how quickly one can install a HWT is for newbees. Short cuts include/rough tank treatment/ missing things like checking tank flapper valves, drip legs, earthquake strapping, leveling the tank, draining off tank debris & pipe soldering flakes to an outlet that won't get plugged by it, checking air supply & venting or just checking the house water pressure.. etc..
> I think the real measuring stick should be how long the HWT that one installs... lasts.


 not bragging at all telling the man that it don"t take 2-3 hours to install tank... thanks though did see where I said it takes us 40 minutes....not my intention...edited my comment....


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## how (Feb 26, 2011)

Hey Ben
This old timer who might be a just bit sensitive about being thought of as pokey when it came to HWT installs, says he hears ya..


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