viessman boiler condinsation

Constantin

... I just read the venting requirements and you're correct, Viessmann specifies Al29-4C stainless vents for vent-only applications. Furthermore, the maximum equivalent distance is 66 feet for most models, except the Vitodens 8-32 and 15-60, where it's 49' of 3" and 4", respectively.

On the other hand, many manufacturers have, and will continue to use plastic flue vent components. Given that a Vitodens will shut down before it reaches critical temperatures and that the concentric vent furnished by Viessmann is made of plastic as well, your blanket statement that plastics have no place in all flue venting applications is inaccurate.

boiler man_2

viessman boiler condensation

Just installed my first viessman boiler connected to a 6" flue pipe to a 7"x11" flue to the top of the chimmney.The chimmney is in the center of the house.I hear that condensation may be a problem because of low stack temps that my rot out the chimmney?I know there are chimmney liners to install in the flues for a smaller flue size.Do you really think this is going to be a big problem? or because the chimmney is in the center of the house it should not be a issue? Looking for some experence tech that has installed and serviced these boilers for so info Thanks

Guy_6

flue

I believe that product is a direct vent product, and therefore can not and should not be vented INTO an existing flue. The approved vent maaterial, be it stainless or pvc, needs to extend from the boiler to the outdoors.
I know that Veissmann people visit this site often, so I am sure that a positive answer will be along shortly.

tom_49

B-man, Which boiler is it?

Steve Ebels_3

Ditto

It's impossible to give and answer without knowing what boiler you have and what fuel you are burning.

What stack temp, CO2 ,O2 and CO did your combustion analyzer show when you tested it?

Ron Schroeder_3

venting Viessmann

B-Man, please call me at 604-533-9445 or mail at mif@viessmann.com

Steve Ebels_3

I'll try again

If you have an ECD or ECV as boiler, you are probably all right. If the boiler is a Vitogas 100 or a Vitola, you are in for a chimney liner.

If the boiler is oil fired, other than a Vitola, you are probably OK too.

boiler man_2

responce for viessmann condinsation

The boiler is a vitorond 200 vr2-40 oil fired.

boiler man_2

viessmann condensation

The boiler is a vitrorond 200 vr2-40 oil fired.

Steve Ebels_3

What was

What was the stack temp? What combustion efficiency did you wind up with? What control does the boiler have on it? This could make a difference in your stack temp if it's utilizing outdoor reset. All of the Vitorond's we have installed wound up at over 85%.

Just curious, not trying to pin you down on anything. The Vitorond is an excellent piece of equipment and will give a long and efficient life if set up properly.

We did a F/A to H/W conversion in a church a couple years ago. Yanked out the two fuel oil ThermoPrides that were serving the existing part of the building and installed a zoned air handler to the existing duct. For the new addition (36x60 with full basement) we installed panel rads. Fuel consumption went down even though an additional 4,300 sq ft were added.

Constantin

Not quite correct, IIRC.

The Vitodens can be vented into a properly lined flue without a problem. Simply remove the concentric intake, take the air in from the boiler room, and you have enough play to allow for a 60' high chimney, IIRC. It's a bit louder this way, but it's also a lot more vent than the 20' that Viessmann Vitodens' are rated for when direct-vented concentrically.

The only downside to such a setup? Somewhat louder operation and the need to bring combustion air into the boiler room (i.e. no longer sealed combustion). IMO, sealed combustion is preferable whenever possible, for a variety of reasons.

The key to any flue installation with a condensing boiler is having the proper vent diameter and material. Since the Vitodens has a very low temp rating, I'd be surprised if you couldn't use PVC or CPVC in this kind of an application to line the chimney flue. Naturally, you couldn't use the original chimney flue for anything else thereafter, lest you melt the plastic.

A look at the installation manual or a call to the HQ in Warwick would answer that question in a jiffy.

marc

vitodens

You are incorrect, the only 2 ways you can vent the Vitodens boiler line in America is by using Viessmann's venting (concentric) for both vertical and horizontal, or
stainless steel venting, ONLY VERTCAL, the advantage with the stainless is longer vertical vent lengths. Dont vent with PVC or ABS or CPVC, those 3 items will eventually cause someone some serious problems. Using plumbing parts as venting for a fuel burning appliance??????????? Marc

Ron Schroeder_3

Vitorond

the Vitorond boiler is a cast iron sectional multipass boiler. It may not be operated in a condensing manner. If you are able to maintian a 250 to 270F net temperature yopu should be able to avoid condensation in the flue as well.

I would consider a liner not to avoid condensation but as a draft management strategy. A 7 x 11 flue is a mighty bug flue for this boiler. Remember that we do not want draft in excess of -0.02" WC draft at the breeching, prior to the barometric damper. A large flue can create a difficult to control draft situation.

Sorry I could not get back with you sooner.

marc

UL listing

i do not recall that pvc, abs, cpvc have any listings for venting. most venting that is used has a listing stamped on the vent. I think it is odd that everything has to be listed for its intended purpose except the venting. marc

Constantin

Do we need UL approval for everything?

The heat and pressure exerted by flue gases in a condensing boiler are nothing compared to the same when carrying hot fluids, for which they are rated for.

It's one reason that converting steam systems to hot water heating are usually a disaster lying in wait - residential steam systems should be operating below 2psi, the operating water pressure found on my hot water system is 12psi. Never mind the added weight that pipes, joints, hangers, etc. in water systems have to deal with also.

And, just because a material or system is not UL-approved to be used with a particular vent system does not make it unsuitable. For example, you could build a gold-based vent system and never have to worry about corrosion... Lastly, I have little to no faith in UL testing standards. It's too simple for manufacturers to rig the test to cover their liability, yet produce a shoddy product. See UL 2034 for an egregious example of this.

Ron Schroeder_3

then allow me to clarify

unapproved plastic plumbing piping has no place in the Viessmann world. Viessmann's own concentric vent material is not a plumbing product diverted for use as cheap venting material. It is purpose designed and manufactured and warranteed by the manufacturer.

Please note that no manufacturers of plumbing pipe have sought approvals for use of their products as appliance venting materials despite the approvals for such applications by said appliance manufacturers. Who knows their products best, the manufacturers of the product or someone else?

Ron Schroeder_3

which is why

we manufacture our own venting material.

Constantin

Absolutely right....

... the concentric vent material that Viessmann offers is a joy to look at and I'm sure that it works very, very well. Furthermore, Viessmann dedicates a whole section inside its venting manual to list the different approved manufacturers of stainless vent materials, with brand names, contact addresses, etc. for vertical applications. In other words, they're trying to make it easy for the installer to do things the Viessmann way.

On the other hand, there are a number of other condensing heating appliance manufacturers out there that use PVC and CPVC for venting and air intake without any issues related to the material (to my knowledge). Hence my (now corrected) presumption that one could run a Vitodens on a plastic vent material even in a vertical application. Evidently, Viessmann thinks otherwise and hence it would be wise to follow their instructions.

As for approvals, allow me to be a bit critical of the need to get everything approved for the conditions it is used for. Sometimes, the intended use is far less stressful on a material than the already-approved-for conditions. Furthermore, I suspect that the lack of approval-seeking by manufacturers of pipe has more to do with liability-avoidance than anything else, allowing them to shift the potential liability from the manufacturer of the pipe to the appliance manufacturer.

Then you can get into political approval processes, such as how the use of PEX in domestic water applications was blocked in MA for years by certain interests.

Ron Schroeder_3

my dear Constantine

I have seen a poly hose at my PH wholesaler that is rated to 150PSI and with NA engineering practise that means it will probably not burst until it is exposed to 450PSIG. This hose is reinforced with a fabric braid and the outsdie cover is UV stabilized. The material does not lose its flexibility in below freezing temperatures.

My local gas inspector informed me that a HO (farmer) had installed this hose in a pressure treated trench in an area inaccessible to wheeled traffic. The hose was used as a 7" WC NG feedline to a small greenhouse boiler. Sizing was correct and the appliance did the job it was being asked to. Do you see any prolems with this installation? Please speak to my question from the perspective of your last paragraph.

Constantin

Very different examples...

... yet, lest we forget, millions of outdoor barbeques are safely lit every summer weekend using some sort of rubber hose to connect the regulators found on LP/NG cans to the burner manifolds.

Coming back to the topic, it is one thing to use a flexible hose to hook up a flammable gas vs. using a thermoplastic as a flue vent material as long as the flue gases do not exceed the physical capabilities of the flue material.

If I am to believe a datasheet from England on the nature of the Viessmann concentric vent, you're dealing with a polypropylene (PP) material, i.e. a thermoplastic. Granted, the PP is more thermally stable at 2x the melting point of CPVC, but it's still a thermoplastic. In other words, once the flue gases exceed 170°C the stuff will melt. And, as I've said before, if Viessmann specifies a specific material for use, then one ought to use it.

On the other hand, I doubt that the manufacturers of the 316Ti stainless used in Viessmann heat exchangers certify the use of their stainless steel for each specific boiler that Viessmann produces. Instead, I presume that they certify that the stainless has a certain metalurgical composition, subsequent resistance to corrosion, etc. in controlled conditions but nothing more. After all, it is up to the engineering staff at Viessmann to determine which materials they ultimately will use, not the supplier.

Unknown

NG can?

You made that up, right?

Noel

Ron Schroeder_3

No but the pressure vessel

and the material it is made of are specifically certified for the application for which they are intended.

Your point of materials being applied in situations for which they were not certified is what I addressed with my story of the farmer who gassed his Greenhouse with garden hose. And why not according to your position. The hose was absolutely overengineered at 150 PSI considering the 7" WC that it was exposed to. Considering that the entire installation was buried in a pressure treated chase rendeder it essentially safe from mechanical damage. No, New Line Hose did not certify their hose for NG use, but according to your position, so what. Had this not been discovered by TAHJ it would have continued to run uninterrupted adfinitum. Had the inspector just been minding his own business, which was to inspect another building on site, no harm would have been done, or would it?

Constantin

Yup... and Nope.

... compressed natural gas tanks are not that unusual outside the US.

For example, Sabre Yachts in Canada furnishes their boats with CNG tanks for onboard cooking fuel and discourages US customers from switching to LP because they believe that CNG is safer in a boating application than LP. Look it up for yourself on their FAQ page, if you like. They even give their US customers local resources to get CNG from...

Besides the much lower energy density, there is no reason not to use CNG vs. LP in many applications. The lighter-than-air property of methane arguably makes it somewhat safer in some applications than LP.

Constantin

Please do me a favor then...

If the manufacturer of the stainless steel used in Viessmann pressure vessels certifies the use of their stainless in a Viessmann pressure vessel, I'd like you to do me a favor and post that certification.

I suspect that it was Viessmann, not the stainless supplier, which had the pressure vessel certified based on testing, design review, and published material properties.

As for your example of greenhouse hackery, I find the example does not fit the argument. The integrity of the chase cannot be guranteed, the wall strength of the hose is not equivalent to materials used in underground gas applications (i.e. black pipe, hard-wall plastic, et. al), etc.

This is a far cry from using two different thermoplastics in a flue vent application if you can gurantee that the flue gases will not exceed the melting/softening point of either thermoplastic. That PP is superior in said application is without question, and I'd always install the appliance to the manufacturers specifications.

Cheers!

marc

failed safety

> If the manufacturer of the stainless steel used

> in Viessmann pressure vessels certifies the use

> of their stainless in a Viessmann pressure

> vessel, I'd like you to do me a favor and post

> that certification.

>

> I suspect that it was

> Viessmann, _b_not_/b_ the stainless supplier,

> which had the pressure vessel certified based on

> testing, design review, and published material

> properties.

>

> As for your example of greenhouse

> hackery, I find the example does not fit the

> argument. The integrity of the chase cannot be

> guranteed, the wall strength of the hose is not

> equivalent to materials used in underground gas

> applications (i.e. black pipe, hard-wall plastic,

> et. al), etc.

>

> This is a far cry from using

> two different thermoplastics in a flue vent

> application if you can gurantee that the flue

> gases will not exceed the melting/softening point

> of either thermoplastic. That PP is superior in

> said application is without question, and I'd

> always install the appliance to the manufacturers

> specifications.

>

> Cheers!

marc

boiler safety failures

> If the manufacturer of the stainless steel used

> in Viessmann pressure vessels certifies the use

> of their stainless in a Viessmann pressure

> vessel, I'd like you to do me a favor and post

> that certification.

>

> I suspect that it was

> Viessmann, _b_not_/b_ the stainless supplier,

> which had the pressure vessel certified based on

> testing, design review, and published material

> properties.

>

> As for your example of greenhouse

> hackery, I find the example does not fit the

> argument. The integrity of the chase cannot be

> guranteed, the wall strength of the hose is not

> equivalent to materials used in underground gas

> applications (i.e. black pipe, hard-wall plastic,

> et. al), etc.

>

> This is a far cry from using

> two different thermoplastics in a flue vent

> application if you can gurantee that the flue

> gases will not exceed the melting/softening point

> of either thermoplastic. That PP is superior in

> said application is without question, and I'd

> always install the appliance to the manufacturers

> specifications.

>

> Cheers!

marc

boiler safety failures

What happens when the limits on the boiler fail and it reaches temperatures above the normal operation conditions and fails, PVC is not even rated for pressure relief valve or T&P valves, but it is ok to vent your furnace, boiler or hwt with it? marc

Constantin

You know,

... that is a really good question to ask the heating appliance manufacturers that allow the use of standard PVC or CPVC pipe with their equipment. I presume that they have multiple interlocks such that the flue gases are not allowed to go above certain temperatures. You could also ask them how many flue system failures they've experienced with the millions of condensing furnaces, boilers, etc. out there.

The Viessmann Vitodens concentric vent consists of a Aluminum outer and a poly-propylene inner tube. Thus, under runaway conditions, I imagine the polypropylene would fail similarly. At least the Aluminum has a chance of containing the mess to the inside of the flue system...