a movement back to water tube mod cons?

hot_rod

I spent several days this week with a group of 35 hydronic reps from across the country. I'm got to chat with multiple reps that sell hundreds of mod con boilers a year, and have been for 10- 20 years or more.

They tell me they are seeing more failures with the fire tube style, leakers, pin holes and excessive scaling that they did with the coiled tube Gianomi style. The theory is the additional water capacity, and hot tube sheet heads actual can cause more problems with scaling, hot spots and failures.

In fairness all brands should have mineral free water to start with, but that is an exception, not the norm in our industry from what I experience in talking with dealers and installers. No heat exchanger is designed to run with scale build up and the thickness of the scale layer, metal temperature, ph, flow velocity all enter into the HX experience.

The water tube style, properly pumped to get a good velocity and scouring currently looks to be the more trouble free of the two styles.

It sometime takes 10 years or more of a track record to get enough data and determine the plus and minuses of the various HX designs.

Any other experiences or opinions?

Ironman

@hot rod
What kind of feed back are you getting on the ECR fin tube HX? I've found those, and the Viessmann, to be very reliable.

Gordy

Where's the beef? Don't change the design just beef it up. Kind of like how ci boilers are not built like they use to be.

Seems though the Germans have stuck with the higher head water tube design with out looking back to far. However I think going back to a mandatory p/s HX is taking a step backwards if that is the thoughts of the manufacturers.

Quite an interesting observation, and adds fuel to the ci vs mod/con debate

I would add it would be interesting to see city, and well water quality changes in the last 50 years. Is it possible our water supply has become more aggressive over time in some regions.

Paul48

Wouldn't it seem as though that information ought to be pointing them towards necessary changes? I get the sense that they are considering "throwing the baby out, with the bath water". Maybe a control strategy that always modulated from least up, would stop localized boiling and scale formation. Isn't that the only way they can produce scale from moving water? And, isn't that the reason for their desire to move massive amounts of water through the HX?

mars_6

I have hundreds of fire tube boilers installed in the Denver market going back 10+ years and have yet to have seen this problem? That being said the water quality in my markeet is very good. Proper ph and very low chlorides. Intresting this is. But not in a good way.

hot_rod

Yes it has too do mostly with water quality, and some designs handle that better. It is not the boilers fault if excessive minerals or bad ph levels, chlorides, or combinations etc cause the problem.

I think their point is that the fire tube type may require even more attention to fluid quality than the small diameter water tube. Perhaps the fire side issues were reduced with fire tube as the condensates would help clean that side, but the water side MAY experience more problems. Both water and fire side are to be attender to, but the problems seem to have basically flopped.

Yes, Gordy water quality from public and private sources is changing, with chloride levels on the increase.

Public water providers are using new and more aggressive chemicals also, Flint MI problems often drive the treatment folks to new or different treatment procedures.

Chlorides, Chloramines and polyphosphates are some of the most recent changes in water treatment.

A wood boiler manufacture I know that builds large water volume type boilers has found a link to polyphosphates and sludge formation in some areas. It seems when the polyphosphates are heated to boiler temperatures the create a gel like sludge in the bottom.

Public water providers are concerned with public health and do not test or treat for hydronic or steam fill water, that is up to the installer.

I think the key to water tube boilers, even copper tube DHW boilers is the flow velocity helps scour the inside of the tubes. With fire tube design, especially when combined with variable speed pumping, low or no flow conditions there is more opportunity for minerals to coat out. Think tea kettles on a stove.

Thick walled cast iron was able suck up those scaling water conditions conditions for tens of years, thin walled SS type HXers, not so well. Older systems piped with steel and copper also minimized O2 ingress.

www.chloramines.org/chloraminefacts

Gordy

So now it's maintain water quality, and /or increase flow velocity through the HX. Seems maybe those could fall under improper installation practices. The latter (flow) adds a dimension to boiler deltas, and efficiency. Also a couple of manufacturers have found it possible to take flows down to 1 gpm through the HX, given the right combination of design criteria.

Any connection as to failures other than water quality as to improper piping, pumping, control?

hot_rod

Gordy said:

So now it's maintain water quality, and /or increase flow velocity through the HX. Seems maybe those could fall under improper installation practices. The latter (flow) adds a dimension to boiler deltas, and efficiency. Also a couple of manufacturers have found it possible to take flows down to 1 gpm through the HX, given the right combination of design criteria.

Any connection as to failures other than water quality as to improper piping, pumping, control?

I agree that it is up to the installer to assure proper installation and assure a long healthy life. In several European countries a fluid standard has been developed and i'm told inspectors check that. I'd prefer to see installers learn some basics and not involve yet another gov intervention

I also agree that less pumping power is a good goal, as is variable flow and temperatures. We are just beginning to see some of the implications of low flow conditions in both scaling, and heat transfer if flow drops to laminar through the HX, perhaps this leads to hot spots also.

We know what happens to low flow or no flow conditions in tank type water heaters, you end up with a good portion of the water sediment in the tank bottom. This seems to be showing up in fire tube boiler also.

Gordy

I was just going to ask if these manufacturers would share their visual media of their findings

Sometimes one does not realize how bad things can get.

Mark Eatherton

We speak about "Reynolds Numbers" a lot when it comes to heat transfer. It's a factor based on fluid velocity. I find it virtually impossible to create enough flow through the fire tube design to create scrubbing velocities. Between that and the tank within a tank design from the same original manufacturer, I've come to the conclusion that the Euros' fail to recognize Reynolds numbers as being relevant...

That being said, as it pertains to hearing scary things from the field, I'm also hearing things about the alternatives to PVC and ABS piping that make the hair on my neck stand up...

Anyone else seeing any issues with improperly supported poly prop venting systems? Seems things have to be exactly "perfect" or issues will crop up...

ME

Gordy

Funny the one HX in the photo is Chicago municipal water fill. The shy towers brag about how great their water quality is as to drinking, and taste coming from Lake Michigan.

hot_rod

Gordy said:

I was just going to ask if these manufacturers would share their visual media of their findings

Sometimes one does not realize how bad things can get.

I see all the manufacturers are becoming more proactive in dealing with fluid quality. It hits someone in the pocketbook when failures occur.

The best info comes from the "street"level guys, installers and reps

JUGHNE

With that many wet-head types for that long, did any discussion of the "coffee grounds" in the water tube HX's come up?

PS: Hot Rod, did you see my PM to you?

Gordy

Curious in the displayed pics of those HXs. How long before someone knew "Houston we have a problem"......that's pretty darn fouled.

kcopp

This has been a topic many of us have been saying is going to be an issue for a while now.... The more high efficiency boilers have been pushed on the market the more issues we will have. Just waiting for the boiler Mfg. to start really pushing water chemistry on the installation as they do w/ doing a combustion test.

@Mark Eatherton ... What have you heard relating to Poly Pro piping? Maybe another thread should be set up specifically for this? PVC is "outlawed" here in New Hampshire...

I

Tinman

@Hot Rod - Those pictures have been around a while. I assume they're coming to the forefront now because of your meeting this past week? We've piped every one of our fire tubes P/S and every one gets torn down every year. We've been paying attention to water quality but we'll have to step that up a bit.

The "self cleaning" claims are BS to a large degree. After one year of use on each of them, they all needed cleaning except one which we cleaned anyway.

hot_rod

Gordy said:

Curious in the displayed pics of those HXs. How long before someone knew "Houston we have a problem"......that's pretty darn fouled.

When they started showing water on the outside

hot_rod

Stephen Minnich said:

@Hot Rod - Those pictures have been around a while. I assume they're coming to the forefront now because of your meeting this past week? We've piped every one of our fire tubes P/S and every one gets torn down every year. We've been paying attention to water quality but we'll have to step that up a bit.

The "self cleaning" claims are BS to a large degree. After one year of use on each of them, they all needed cleaning except one which we cleaned anyway.

I've got plenty of pics, and I see returns at suppliers as I travel. I'm not trying to hammer the boiler manufacturers, just showing results of ignoring warning cautions and lack of fluid knowledge and maintenance.
Also wondering about longevity difference between the various HX styles, subjected to exact same conditions.

Tinman

I see the lack of maintenance all the time. It baffles me. I maintain my pencil sharpener.

hot_rod

JUGHNE said:

With that many wet-head types for that long, did any discussion of the "coffee grounds" in the water tube HX's come up?

PS: Hot Rod, did you see my PM to you?

Nothing recent in my PM box?

Gordy

I think one can say with a great amount of certainty this happens in ci boilers of all designs. It just goes unnoticed until percolation starts, and efficiency plummets. Unlike a water, or fire tube which has narrower passage ways, and fouling leads to catostrophic failures.

Gordy

Stephen Minnich said:

I see the lack of maintenance all the time. It baffles me. I maintain my pencil sharpener.

People have a tendency to not maintain something until it is broken. Usually to late, and leads to more parts, and higher costs.....This holds true with all things that could use a preventive maintenance schedule for the majority of the population.

Paul Pollets

I've replaced at least 6 of the Viessmann first generation heat exchangers (WB2A series) that I started installing 15 years ago. I've over 40 of these boilers installed. All but one were maintained and cleaned yearly. That said, until Viessmann made a special cleaning tool available 2 years ago, it was nearly impossible to remove debris and carbon deposits from between the sections of the HX. A cut credit card was ineffective. Now I'm thinking that if one of the special blades were attached to a small oscillating tool (Fines tool) at a 45 degree angle, debris could be removed quickly and effectively.

hot_rod

Paul Pollets said:

I've replaced at least 6 of the Viessmann first generation heat exchangers (WB2A series) that I started installing 15 years ago. I've over 40 of these boilers installed. All but one were maintained and cleaned yearly. That said, until Viessmann made a special cleaning tool available 2 years ago, it was nearly impossible to remove debris and carbon deposits from between the sections of the HX. A cut credit card was ineffective. Now I'm thinking that if one of the special blades were attached to a small oscillating tool (Fines tool) at a 45 degree angle, debris could be removed quickly and effectively.

What is an acceptable life of a piece of equipment like that in the homeowners mind, or ours?

Ballpark $$ to replace a boiler with near identical model?

Gordy

I won't speak for Paul, but if the homeowner had a ci boiler that lasted 25 years, or more I would think that sets the bar in their mind. Especially when a high efficiency replacement costs more.

In most homeowners minds the fact that the two boiler designs are far different should not matter.

Larry Weingarten

Hello, With the advent of inexpensive IR imaging, (think Flir One) it might be useful for a manufacturer to develop a sensor that "looked" at the heat exchanger for hot spots. Modern tech could likely then notify somebody that there is a problem that needs service. Just a silly thought

Yours, Larry

Paul Pollets

Hot Rod, Most homeowners replace the HX, one replaced the boiler with the newest model. All were concerned with having to spend significant dollars 10 years later. While it's not planned obsolescence, I would expect 20 years. That's not the case.

JUGHNE

Paul, how close is the HX cost to complete replacement with warranty etc.
Or was the HX offered no cost by manf.

Paul48

How frequently are they replaced and what is the expectation of longevity in Europe? I read an article several years ago, that stated that they expected to replace their boiler every 5 years, or so. It was summarily dismissed when I said that, here.

Paul Pollets

Some of the replaced HX were within warranty, several not. I was told they would last "20 years" with maintenance. Don't know what was the European expectation for life expectancy. Warranty replacement never covers labor cost. Many of these units require a new circuit board after ten years, like other computer driven appliances.

Gordy

Larry Weingarten said:

Hello, With the advent of inexpensive IR imaging, (think Flir One) it might be useful for a manufacturer to develop a sensor that "looked" at the heat exchanger for hot spots. Modern tech could likely then notify somebody that there is a problem that needs service. Just a silly thought

Yours, Larry

Interesting thought Larry. Or just sensors in key areas prone to hot spots that would be integrated into the program logic to down fire, or increase flow rate.

Gordy

It would be interesting to know if they have fluid quality issues across the pond. If they are proactive, or case by case in fluid maintenance, and boiler maintenance. I know my uncle who lives in northern Italy has the yearly gov. Required inspections at about 150 €. Of course he thinks it's a racquet

bob eck

Hot Rod questions the photos of the fire tube heat exchangers.
What type of system was the boiler installed on?
What did the water look like when the old boiler was taken out?
Was there any cleaner fluids put in the system before the new fire tube boiler was installed?
Any type of dirt magnet unit installed on this boiler system?
Any type of leak in the system where the auto water feed was putting new water in with fresh oxygen in the water?
Was the boiler installed with the outdoor reset sensor or was the boiler running with high water temps?
Was there pex tubing installed on this job? If so was the pex tubing a radiant barrier type tubing?
Was the boiler piped P/S? Did the boiler have the right primary pump to make sure the fire tube heat exchanger had the right GPM going through it?
As far as I know there are many factors that can kill a fire tuber or water tube boiler heat exchanger. Many of these factors are not the fault of either type heat exchanger.

Tinman

I'm hoping that what Hot Rod saw was a very small percentage of failures and due to poor installations and lack of maintenance as he mentioned.

That said, am I asking too much for engineering departments to be as important as marketing departments to the manufacturers?

Gordy

Not at all. There should be a direct circle from sales, reps,design/engineering Stephen.

kcopp

Gordy said:

It would be interesting to know if they have fluid quality issues across the pond. If they are proactive, or case by case in fluid maintenance, and boiler maintenance. I know my uncle who lives in northern Italy has the yearly gov. Required inspections at about 150 €. Of course he thinks it's a racquet

Gordy.
Looking at all the UK companies I follow on Twitter they are huge into chemical treatments and magnetic filters.
Fernox, Adey pro and Magnacleanse , Calleffi to mention a few....
Also the power flushing set ups are also big there.
The UK boiler market is prob the largest market in the world.

bob_46

Regards the Hot Rod photos Chi. puts a mixture of polyphosphates in their water to coat the inside of pipes to protect against lead. That said, it's hard to believe there would be enough phosphate or mineral in the initial fill to create that much stuff. If you boiled down 20 gal. I wouldn't think you would get more than a teaspoon full if that.

hot_rod

kcopp said:

Gordy said:

It would be interesting to know if they have fluid quality issues across the pond. If they are proactive, or case by case in fluid maintenance, and boiler maintenance. I know my uncle who lives in northern Italy has the yearly gov. Required inspections at about 150 €. Of course he thinks it's a racquet

Gordy.
Looking at all the UK companies I follow on Twitter they are huge into chemical treatments and magnetic filters.
Fernox, Adey pro and Magnacleanse , Calleffi to mention a few....
Also the power flushing set ups are also big there.
The UK boiler market is prob the largest market in the world.

Keep in mind them UK still installs open systems in many cases. Up high in the building is an open expansion vessel. That may be why several of the treatment companies are located there?

We had a guest wholesaler from the UK on our webinar a few years back. It is also one of Caleffi's largest market.

They have an interesting theory about softened water and hydronics.

hot_rod

bob said:

Regards the Hot Rod photos Chi. puts a mixture of polyphosphates in their water to coat the inside of pipes to protect against lead. That said, it's hard to believe there would be enough phosphate or mineral in the initial fill to create that much stuff. If you boiled down 20 gal. I wouldn't think you would get more than a teaspoon full if that.

It was Garn boiler that contacted me with the info about sludge formation from polyphosphates. Their boilers hols between 1000 and 3200 gallons, plain steel, open system.

Sal Santamaura

Stephen Minnich said:

...am I asking too much for engineering departments to be as important as marketing departments to the manufacturers?

In all industries, generally speaking (there might be a small number of exceptions), yes!

Tinman

I thought so.