Aluminum Heat Exchangers

Steve Ebels_3

No, I see exactly what you mean

And I concur 100% that we should get together and drown our sorrows over a couple longnecks of Lennie's Sunset Wheat with the appropriate steak

I also could not agree more that some manufacturers are designing their product to the lowest common denominator, IE low first cost. I'll probably take some flak as being a Viessmann groupy but if more manufacturer's took the orange and silver point of view regarding total life cycle cost, the world would be a better place and my life would be a whole lot easier. I also think that in an effort to keep production costs as low as possible, long term or field testing gets skipped by a lot of them. If in fact that testing was being done I wouldn't be seeing some of the issues with condensing appliances that I am running into. Sometimes though no matter how much idiot proofing a manufacturer undertakes, they are stymied by the fact that better idiots are made every day.

AFA the young engineer issue goes, I have long held the belief that no one should undertake the design of a product until he/she has spent at least a couple years in the field troubleshooting and repairing the items being sold. To me, it goes back to building in a margin for error and the variables encountered out in the real world and not on the test bench in the company lab. But then, that would probably also drive short term costs too high for the bean counters to accept.

Many of these boilers are designed with virtually no thought or foresight given to being serviceable or easily maintainable. To me it's a travesty because if something is easily serviced then the service tends to be done when it should be.

But even in the event that a boiler is easy to service a homeowner will still neglect to do so or to have someone do it. I spent about a half an hour on the phone last week with a contractor friend from the thumb who was trying to figure out a way to dislodge a Vitodens burner that was literally stuck in place due to all the buildup in the HX area. The unit had been in service for about 5-6 years from what he could tell and no one had ever laid a finger on it. In the end several parts had to be replaced due to damage from dis assembly. The complete lack of care and maintenance nearly resulted in an early grave for a fine piece of equipment. That too is wrong and that particular homeowner must bear a share of the blame for an expensive repair. My friend now has an annual service agreement with that homeowner.

singh

Gordy

Well I guess we have to agree to disagree then.

Would someone explain to me why it's unacceptable that a mod/con won't last for 30,40,50 years or whatever your view how long they should last, I'm sure there are some out there that would say as long as the house is standing. No one as of yet has clearly conveyed that thought, why they should last as long as you what them to?

Unfortunately in my view of the world, I see good money being thrown into automobiles that are pretty much worthless after 10 years or so, In the home , refrigerators, ranges,water heaters,dishwashers,microwaves, window a/c units,flat screen tv's , computers, fax machines,printers etc..

If I were buiding or renovating a home today, first I would spend time and money on passive approaches to the structures HVAC system, i.e. insulation, windows, site orientation,landscaping and so on. I would double or triple the budget for those items.Knowing they'll be a part of the house for 100 years or more. Next I would spend some coin on DOAS, as part of the system,rather than the "best boiler" money can buy.
Last, I would install a "decent" mod/con boiler, and if 10-15 years is the useful life so be it, it was not the intent on being "the system", only a component to supplement the system. The house itself is the system.

And if your just looking for a replacement boiler, but can not financially make improvements to the shell,then communication should be established between you and the installer as far as the "energy savings" and "longevity" of these units.

The only good thing about installing a mod/con replacement is that they weigh 100+ lbs, other than that not always the best fit.

On another note, but while we're at it, there seems to be a growing interest in ground source water to water heat pumps, big $$ but on a hydronic system in a heating dominent area they are really taxed to the limit, how long should they last? Its going to be ugly for those installing these units in 10 years or so. But now is the time to have the discussion, unlike mod/cons which almost over night became increasingly acceptable , with no thoughts on how long they should last.



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[Deleted User]

Think of the negative environmental impact of the manufacturing, distribution, and installation of three boilers over 30 years rather than one boiler. This is one reason that I don't buy into the 'green' movement. It's just another marketing ploy. The fuel you didn't burn and put into the atmosphere got burned by someone else in the process of making you a responsible member of the planet. We had an EPA refresher course and I started thinking about how much energy and materials were exhausted since the 90's due to the recovery of refrigerants. I agree with doing it, but the EPA course could be trimmed down. Here's how - Here is a recovery machine and a tank. Put the refrigerant into the tank. If you get caught illegally venting you'll get in trouble and have to pay a fine. Done in a few minutes. Instead we have - Tell me when the Montreal Protocal went into effect. Notice how there is no more 'Global Warming'? It's now called 'Climate Change'. That way if the temp goes up or down they can tax us for it.

Gordy

D.S

Exactly but with a boiler you have a CHOICE a conventional boiler will out last a mod/con with less maint., AND a conventional boiler is CHEAPER! Go Figure.

I say so as a consumer that I want the best I can get that will last the longest.

As far as Autos I got a 99 dodge avenger, and a 01 tahoe. Both have over 100,000 miles. I just dumped 2 grand in the tahoe for rear wiper motor, and heater core for the front. The avenger I have put very little money into broken things.

I don't throw the baby out with the bath water as long as repairs do not cost almost as much as the product.

Appliances Of the old tended to last longer then today of every sort. I remodeled my kitchen 3 years ago, and the appliances were still all working from the late 70's. We will see how GE fairs with the new ones. T.V's I have also good luck.

My conventional WM boiler is a 93. 15 years old no problems. The one before it lasted 45 years. Yeah its double the size, its only low 80's efficiency, It can't condense or modulate. But its still there year after year. I want to change over to a mod/con, but the more I read here, I just don't know the proofs not out in my eyes.

My Uncle is here for Christmas from Italy 3 years ago he put in a new mod/con. This year he put in a pellet stove so he did not have to buy gas. As you know nothing is cheap across the pond. Now he only uses the boiler for domestic production.

Gordy

Perry_7

I actually agree with your intent - just not your conclusions.

Yes: The whole house is the system.

So lets look at how to minimize energy cost longterm.

The boiler is only one part of that system. They are inherently expensive to replace.

Is it more economical to install a 10% lower efficiency boiler that last many decades or is it long term more economical to install a 10% higher efficiency boiler that has to be replaced more often.

If you look at that question - and the cost associated with maintaining and repacing a 85% efficiency boiler every 30 years and a maintaining and replacing a 95% boiler every 15 years.... I think you will see that the 85% boiler is the most long term cost effective.

I thing that a Mod/con boiler will need to last 20 years - or more - to be economincal in the house system approach.

Perry

Perry_7

Not totally a marketing ploy - but often misused

The concept of "Green" should be looking at total life cycle cost - including the energy and environmental cost of manufacturing the item or system.

Once you include the energy and enviromental cost associated with manufacturing you are driven to long life components and systems.

Of course, the vast majority of US "green" advertising is only focusing on short term isolated efficiency gains - aimed at building immediate market share for a company or product. These people don't give a hoot about being really green (except for the money they get).

Perry

Drew_2

ModCon costs

I've been reading the posts with great interest in the comments. Thought I'd pick a few that I can address.


1. Here is a direct quote from someone's posting on a blog back then in Europe: "Aluminium heat exchangers have a tendency to rot away with time and leave a slimy mess for the service engineer."

Very true, but we in the U.S. assume that the Europeans knew everything about the corrsion issues associated with various metals when they brought them to our market.
What I found when developing inhibitors was that boiler manufacturers knew very little about corrosion. This lack of knowlege was not exclusive to the U.S.

2. Yes, you can protect the waterside of a Aluminum Boiler HX via use of a good corrosion inhibitor package.Unfotunately, this is not a one time thing. You have to sample every year or two, have a lab analysis done, and then retreat the system to bring the corrosion inhibitors up to snuff.
That means a lot more service calls. Who is going to do it? who is going to pay for it? Who is going to pay for the lab analysis?

I've noticed that most of the contractors on this board recommend that boilers be inspected and cleaned every year.
This is the time to check the inhibitor/fluid/antifreeze that is in the system. So I don't see the extra service call issue. Will the corrosion additive need to be replaced during the life of the boiler? Probably, sort of like the fluids in your automobile. They don't last forever.
The lab analysis/testing of the fluid/additive can be done by the manufacturer of the additive. The Noburst product that we manufacture is tested at no-charge to the user. Make sure your buying your inhibitor/Antifreeze from a technically knowlegable, fullservice manufacturer.

3. Once those inhibitors break down... so does the Aluminum HX.

If you are using antifreeze with an inhibitor you are correct.
I can say that we have been putting Noburst AL in systems for over 5 years and have not seen a failure with the inhibitor that is used.

The talk about HX material made me look at the thermal conductivity of various metals. Here's what I found;

Thermal Conductivity
Copper .941
3003 Aluminum .460
Cast Iron .112
304 stainless Steel .036

Andrew Hagen_2

Materials

When considering thermal conductivity, it is important to remember that those numbers are typically given per inch of thickness. Aluminum heat exchangers are typically much thicker than stainless steel ones, and therefore the actual conductivity is much closer.

The heat exchangers *should* have been designed to take the thermal conductivity into account.