Is AL29-4C superior or just new?

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btuser

Minister of Fire
Jan 15, 2009
2,069
Principality of Pontinha
I'm planning on finishing a boiler install this Summer and thinking about relining at the same time. The boiler is capable of 89% + efficiency with flue gas in the range of 220F-275F degrees gross (not net) stack temp. Not quite condensing (so plastic is out of the question) but after spending the money on such an efficient appliance I DO NOT want to open up the air and push more heat out the chimney just to raise the temp. The existing chimney was built in 1994, is 8x8 clay lined in good shape. It is on the East side of the house, exterior on 3 sides, and about 20' from tee to cap. The new flue size will be 5", so relining isn't a bad idea because from what I've observed the current draft is not impressive.

I plan installing myself. I am going to insulate the new liner. My main question is what type of stainless to use. 316ti vs al29-4c alloy. I have read that 316ti should be fine for non-condensing oil boilers, and have read to the contrary as well. It seems if manufacturers are making condensing chambers out of 316ti it should be fine, and there's no reason for the added expense of a patented alloy with a premium price.
 
btuser said:
I'm planning on finishing a boiler install this Summer and thinking about relining at the same time. The boiler is capable of 89% + efficiency with flue gas in the range of 220F-275F degrees gross (not net) stack temp. Not quite condensing (so plastic is out of the question) but after spending the money on such an efficient appliance I DO NOT want to open up the air and push more heat out the chimney just to raise the temp. The existing chimney was built in 1994, is 8x8 clay lined in good shape. It is on the East side of the house, exterior on 3 sides, and about 20' from tee to cap. The new flue size will be 5", so relining isn't a bad idea because from what I've observed the current draft is not impressive.

I plan installing myself. I am going to insulate the new liner. My main question is what type of stainless to use. 316ti vs al29-4c alloy. I have read that 316ti should be fine for non-condensing oil boilers, and have read to the contrary as well. It seems if manufacturers are making condensing chambers out of 316ti it should be fine, and there's no reason for the added expense of a patented alloy with a premium price.

The 316Ti should be just fine for that use. About the only thing that will bother it is chloride in some form or another. I am aware of only 2 boiler manufacturers that use it for HX material and one of them is Viessmann. If they feel it's suitable it probably is. I don't know of any boiler manufacturers that use AL29-4c for heat exchanger material as that alloy is more suited for sheet products rather than the thickness a boiler HX requires. Trane and Thermopride are the only furnace manufacturers that use it. It's probably the best alloy available, considering cost, for that use.

You are wise to install a liner in your clay chimney. When I started using the European products, Viessmann and Buderus, I never gave liners a thought. I learned real quick that low temp flue gas and the resulting condensation will destroy even a clay lined chimney in a very short time. Needless to say we had several installs that we went back to and dropped in a liner. We use the 316Ti for oil and 304 grade for gas.

Here's a couple of links that will tell you more than you ever wanted to know. :)

http://www.alleghenytechnologies.com/ludlum/Documents/316Ti.pdf

http://www.alleghenytechnologies.com/ludlum/Documents/AL29-4CRev2010-Brochure.pdf
 
Thanks for the link. Here's another I found for the difference between the 316 alloys:
http://www.bssa.org.uk/cms/File/SSAS2.25-Comparison of 316 & 316Ti Types.pdf

It states the value of titanium is for increased resistance/strength during high heat (400C and up). I'm looking at closer to 100C so it should be good.
 
OK, now I have guilt.

This is for an oil boiler.......
 
Hmmm, for oil the basic thing is to clean it well in the spring and maybe brush down a neutralizer (baking soda or other base).

In the case of oil, the 316 may offer a longer life - however, most oil boilers have gone long periods (20+ years) even with the standard stuff, so any upgrades are probably optional. Make certain that whichever brand you buy specifically extends their warranty to oil....it will usually say do in the warranty or on the specs for the liner.

In the case of a regular boiler, just about any grade will do, but if the boiler is extremely efficient and might condense some (even if not a condensing model) the higher grades will help. Insulating the liner will do a lot to extend the life as that retards condensation.

I say the 316ti might be a good choice in this case - if you want to really do the job right, use rigid as opposed to flex.....and use a smaller size (if that matches the boiler spec)....no bigger than the flue collar.
 
Actually, when it comes to diameter, a person should check with the manufacturer as overall height enters into the equation also. Flue collar diameter is right most of the time but not always.
 
I'm going with smooth wall double thick 316ti with a wrap of 1/4" insulation. I'm also going to insulate the interior flue pipe from boiler to thimbel, install a tee at the bottom cleanout for inspection/critter removal, top plate and the rest of the kaboodle. Al29 alloy does seem to be superior in resisting chlorine pitting (as noted above-thanks for the tip), but that doesn't seem to be an major part of oil combustion products. 316ti does just fine with sulfuric acid coming from the sulfur in the fuel. Of course who knows what they will end up putting in th fuel to get the sulfur out once low sulfur heating oil becomes mandatory.

Heaterman- Any tips/nuances when it comes to Viessmann Vitola w/ riello burner?
 
btuser said:
I'm going with smooth wall double thick 316ti with a wrap of 1/4" insulation. I'm also going to insulate the interior flue pipe from boiler to thimbel, install a tee at the bottom cleanout for inspection/critter removal, top plate and the rest of the kaboodle. Al29 alloy does seem to be superior in resisting chlorine pitting (as noted above-thanks for the tip), but that doesn't seem to be an major part of oil combustion products. 316ti does just fine with sulfuric acid coming from the sulfur in the fuel. Of course who knows what they will end up putting in th fuel to get the sulfur out once low sulfur heating oil becomes mandatory.

Heaterman- Any tips/nuances when it comes to Viessmann Vitola w/ riello burner?

Sounds like you have the chimney handled there. Good plan.

As far as a Vitola goes, you have the M1 Abrams tank of boilers my friend. I cannot say enough good things about it...... excellent efficiency without the complexity of condensing, you cannot cold shock it, extremely long service life, well insulated, capable of firing oil or gas with a burner change should market conditions warrant, super easy to clean and maintain......what's not to like except it's expensive and weighs a ton. :)
Give it a good setup and routine annual maintenance and I really don't know how many decades of service one could expect.

I have a Vitola with a natural gas Viessmann chassis burner in my own basement. I installed it in the fall of 2003 and as an experiment I have not cleaned it or serviced it in any way since I dialed it in. I open the burner door once a year, look in there, shake my head in disbelief and bolt it back shut. I have done nothing to it and the clock now shows about 16,700 hours of burner run time.

The Riello is an excellent burner. It has to be set up and dialed in by a tech with a combustion analyzer, as do all oil burners, but once you get it adjusted they need nothing other than normal maintenance. CO2 should wind up a tick or two above 13% with 0 smoke and you efficiency will be 86-88%. The burner will be close right out of the box in most cases because they are all test run by Viessmann. I have a virtually unopened oil burner parts kit that I bought in 2001 when I started selling and servicing Riello. Never used a single part from it if that tells you anything.

You will enjoy that combination immensely.
 
Yeah, it was heavy. I used a chain hoist and appliance dolly. I can see how a small low mass boiler would have its appeal in a bulkhead installation.
 
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