A rare All Steamed Up, Inc. Atmospheric

Steamhead

We don't recommend atmospheric gas boilers, since they are not as efficient as wet-base, power-burner units. But this customer really, seriously wanted another atmospheric.



The system is a Webster Vapor, probably a Type R originally but the return trap is long gone. We found the dry return tee for the line to a Return Trap, it now serves as a main vent location. Gordo has been working on this system for some time, and he had installed a Gorton #2 there.



The Burnham IN9 had rotted out above the waterline, this time at the second section from the return connection. You can see the familiar hole.



Based on what we've seen, this rotting-out is not exclusive to Burnham. We have replacements proposed for a couple of other brands as well, that have suffered the same fate. They're all atmospheric gas, though.



The return had quite a big sludge ball in it. And it would not have been possible to flush it out, the way this was installed. This is why we use so many plugs and caps.

Steamhead

The new Peerless 63-06

One of the nice things about this one is it doesn't require two risers to the header, which meant we could tie in both steam mains neatly without a lot of heroics. The riser and header are both three-inch, and both mains are two-inch.



We installed a secondary LWCO on this job, and used a remote probe so the control itself would be more accessible. And the Vaporstat on the old boiler was only a couple years old, so we used it on the new one.



Gordon did his usual nice piping job on the returns, and we added another Gorton #2 vent. The system vents on about 1.5 ounces of pressure until the crossover traps close.



Look at the Pressuretrol that came with the boiler. Every new PA404A we see is cranked all the way up, and a surprising number of them are left that way until we get there. It makes no sense to ship them cranked up- safety would dictate they be shipped cranked down.

Charlie from wmass

I was thinking about the

cranked up pressuretrols. I think they do that so the screw does not vibrate loose during shipping. Another nice piping job but you knew that. The picture showing the returns at a quick glance looked like you had fed the system between the risers. I had to do a double take. I think I will go get another coffee. I think the boilers are being killed by excessive fresh water. and I also think the fire rate on many atmospheric boilers is too high, The pins should stop just below the water line IMHO.

Mike Kusiak_2

Calibration

I have a feeling that the reason the pressuretrols are left set at the top of the scale is that this is the pressure at which they are calibrated. After calibration, they are just left at that setting and shipped. 



Probably the reason why the controls are so notoriously inaccurate at low pressures, since they are only checked for accuracy at the highest scale setting.

Steamhead

Ahh yes, the swing joint made it look like that

an unintended optical illusion.



We did find a leak in a drip after we fired it up. Gordon is over there now fixing it- just a badly soldered joint. It must not have shown up before since the old, leaky boiler could not build enough ounces of pressure to make it leak. But there's no way to tell how long it had been like that- it wasn't in a place where the water would make a puddle.



The VXT feeder will tell us if there are any more leaks. In light of all these rot-outs, there's really no reason to use any other type of feeder.



Mike, we've all wondered why the PA404 series is so inaccurate- you may have the most plausible explanation.

The Steam Whisperer (Formerly Boilerpro)

Nice Job....

I've been working on standardizing on the Galaxy for our smaller jobs and using the Peerless 64 for the bigger or for a little more efficient smaller boiler. A single riser really helps simplify the piping,

If you do a little looking, you'll find that the thermal efficiency of the 64 is close to the power burner models.  If they'd do something about the radiation losses off the bottom of the burners, cut down the excess air, (I measured about 75% in my recent install),  improve the insulation and get rid of the drafthood and install a baro with vent damper, I bet they could exceed the real life efficiency of a power burner.  The AHRI ratings for the Intrepid with a power gas burner are about 80% thermal efficiency and the 64 is at 79%.

Those VXT's have saved alot of systems I've worked on from an early demise.

Brad White

Steamhead, what is

your take on this epidemic of rear or near rear section high perforations? You reported that in another thread and with your volume, you are seeing more than most, to the point that the hole is "the familiar hole".



I am looking at a V11, installed in 1998 which is leaking out the back around the flue collar or at least that is where the steam makes its way out of the jacket. Quite the sight to see under pressure. These are young boilers. I have asked about any chemicals stored nearby, nobody seems to know.



I am reluctant to go about replacing a boiler until I have at least some handle on why they spiral down like that.

Steamhead

Interesting site

www.ahridirectory.org for those who aren't familiar. The Search functions are pretty self-explanatory, and you can click on an individual boiler's one-line summary to get more details.



The 7-section Intrepid certainly has a lower rated thermal efficiency than the smaller ones- these range from 85 to 87%. My guess is that this model and the Caravan wet-base units are fired more aggressively since they are considered commercial models, and therefore don't have to undergo AFUE testing. Note that the smaller Intrepids don't list thermal efficiency since they are rated using AFUE, so I determined thermal efficiency on these by dividing the Gross or DOE output rating into the Input rating. When I do the same on the commercial ones, it matches their listed thermal efficiencies, so this is probably the correct way.



I'll ask about this next time I talk to the guys at Slant/Fin.



I also measured higher-than normal excess air on this one, as you described. What might it take for Peerless to "do something about the radiation losses off the bottom of the burners, cut down the excess air, (I measured about 75% in my recent install),

 improve the insulation and get rid of the drafthood and install a baro"? I think the answer would look a lot like a MegaSteam.

Steamhead

I'm guessing high chloride levels in the water

and maybe because dry-base atmospheric sections run hotter since they seem to have less heat-transfer surface than wet-base sections. All of these boilers are hooked up to the Baltimore metropolitan water delivery system, which has two treatment plants. I think the time has come to have an independent lab test some samples.

Brad White

Mmmmm

While chlorides are suspect, if they are in the water, the PPM has to be pretty high to make that attack.



I was thinking chlorides on the fire side where HCl is created in combustion from the outside.



Is there a definite "inside to outside" pattern to the corrosion? In other words is the greater material loss on one side, tapering toward the hole? And that the hole winds up in that same place- hotter flue gasses, perhaps?



Interesting stuff! Eventually we will get a handle on it. I'd love to see what a lab would say. Maybe ASTM and ASME might have an interest in this pattern?



Thanks, Steamhead.

Steamhead

All the ones I've seen so far

rotted out from the water side. The fire side was perfectly smooth around the hole.



You might check the coil plate gaskets on that V11- the plates are located along the right side of the boiler.

Mike Kusiak_2

Concentration of mineral content?

I wonder if the the basic atmospheric design inherently tends to concentrate the salts and minerals present in the water on the inner surfaces just above the water line?



Since the top of the exchanger is not backed by water it reaches a temperature much higher than boiling, and therefore evaporates any water splashed on it immediately, depositing and concentrating any dissolved substances on the surface. If chlorides are present they will be at a much higher concentration in this region and when not being fired may cause significant corrosion in the humid environment above the water line.



Just a thought, but it might explain why the corrosion occurs precisely at a point just above the water level. Kind of like the ring of dried material that you see at the top of the pot when making a pot of soup, corrosive salts may concentrate above the boiler water line, causing accelerated corrosion.

Steamhead

You might be right

if so, it wouldn't take many PPM to start the process. 

Ex Maine Doug

Ring of crud

"Kind of like the ring of dried material that you see at the top of the pot when making a pot of soup"



Ah, the bathtub ring effect. Best to be the first in line on bath night.