Boiler Leaking - Either Piping or Heat Exchanger - Thoughts?


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Old 12-12-13, 07:30 PM
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Question Boiler Leaking - Either Piping or Heat Exchanger - Thoughts?

I will try to keep this brief, but it will take a little explaining.

History: 9 year Old Weil McLain Boiler (Ultra 80) which I have had problems with every year from day one. Leak of factory pipe (thin wall at bend) directly out of heater at about the 5 year point. Firing issue for a couple years. All zone valves had to be replaced and a multitude of other issues. Finally most items have been nailed down and things were running pretty smooth last year.

Then had a FillTrol tank go bad (mounted sideways so air caused corrosion) late last winter and we limped along till summer to get it fixed. Once installed and system refilled and air bleed it was doing great. Expansion tank pressure holding steady at about 60 psi and the boiler and FillTrol tank pressure and boiler pressure holding between 12-15 PSI. Since the system is in my workshop, I try to check it weekly and most of the time I do.

Last week was really cold (-3 degrees) and the system was running better than ever and here is where I should have knocked on wood. About 3 days ago, I started noticing the condensate pump running more. Did not concern me at all, because with it being so cold, it is likely to condensate more, so my thinking goes. I even remarked to my wife that the condensate pump was running more and that the heater must be running more efficiently. More on this later in Theory #2 ....

One day later we hear gurgling (air in the lines) in the afternoon and when I check the Expansion tank it as at 0 psi and the boiler as well was at 0 psi. Ugg! So, I started looking for pipe leaks and could not find any (scoured the visible pipes at least three times now). The entire in-floor part is covered with Reflextix and insulation, but can be easily inspected from below in the basement. The up stairs is radiant baseboard and most of it can be visually inspected easily as well.

So after thinking it over, I decided to pressurize the system again, this time without the boiler firing (read no evaporation thus making it easier to spot any leaks). Unfortunately without the proper pumps to quickly purge the system of air, I have to rely on the "Spirovents" located near the boiler (out and return lines) to eventually get the air purged out which takes a lot more time than the other way. They do not seem to be functioning as efficiently as when new.

Went to bed with the Expansion tank at 70 psi and it was down to 40 psi by morning, but less air in the lines at least according to my ears. Boiler never dropped below 12 psi all night and all pumps still running with natural gas off to test my theory. So, throughout the day, I have been making sure the Expansion tank that feeds the FillTrol tank is around 70 psi and 24 hours later I still have air in the line. Although less than before. My current thinking is that the Expansion tank is only providing replacement water for the purging air. We will see. If not, perhaps I will at least be able to locate the leak once enough water leaks out.

Theory #1: Leak in one of the lines and just have not found it yet. Once I get the air purged, if the lines hold pressure for a few days, I will rule this one out.

Theory #2: I have an internal crack in the heat exchanger causing the water to get pumped out through the condensate pump when the boiler comes up to temp. Note that the boiler is currently within the pressure loop and there is no water leaking into the condensate trap at this time.

Anyone been in this situation before?
What are your thoughts?
Any help or additional troubleshooting tips would be greatly appreciated.

Thanks,
SDesign

Edited original post to reflect proper tank naming FillTrol was used incorrectly etc.
 

Last edited by SDesign; 12-12-13 at 09:19 PM.
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Old 12-12-13, 08:31 PM
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FillTrol tank pressure holding steady at about 60 psi and the boiler pressure holding between 12-15 PSI.
HUH? Say WHAT?

FillTrol tank pressure HAS TO equal the boiler fill pressure! That's the whole purpose of the FillTrol system!

Are you sure you have a FillTrol? Where the tank is 'special' and has a built in 'push rod' that activates the valve it is attached to?

Or do you have a standard EXTROL expansion tank?

Either way, if you have the tank pumped up to SIXTY PSI, that is WRONG, WRONG, WRONG!

When boiler is cold, expansion tank pressure is supposed to EQUAL cold fill pressure!
 
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Old 12-12-13, 08:34 PM
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and when I check the FillTrol tank it as at 0 psi
I have to say HUH? again, sorry...

Even if the boiler loses pressure completely, you should STILL have the 12-15 PSI in the tank because it is SEALED by the diaphragm inside the tank.

Something is either VERY wrong there... or there's a basic misunderstanding of how an expansion tank on a boiler works.

Then later I read that you've got the FillTrol pumped to SEVENTY PSI?

May I ask why it is that you are pumping the expansion tank to more than five times the pressure that is SUPPOSED to be in that tank?

You need to take some pictures so we can see what it is that you are working on. Show us the FillTrol valve and tank in particular.
 
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Old 12-12-13, 09:10 PM
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More details

Sorry, what I meant to say is that I have a pressure tank Amtrol Model 30 that feeds the FillTrol tank (same size as Amtrol 30 tank). Of course, the FillTrol tank is at 12-15 psi. Sorry for the confusion. The FillTrol feeds water from the Pressure Tank (holding tank) when the system pressure drops below 12-15 psi. Basically almost everyplace I said FillTrol, I am referring to the expansion tank, NOT the FillTrol tank. Again my apologies, it has been a long day.

I have edited the original post to hopefully reflect the proper tank names and configuration.

I am extremely familiar with how the system works and how the expansion tank/ FillTrol configuration is set up. No need to worry about it being installed incorrectly, I promise you. 8-)
 

Last edited by SDesign; 12-12-13 at 09:35 PM.
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Old 12-13-13, 06:32 AM
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I am extremely familiar with how the system works and how the expansion tank/ FillTrol configuration is set up.
OK, that's fine... but I'm not at your house to see how this system is piped, and I still have no idea what you're talking about.

What is this 'expansion tank' you are talking about? Are you talking about something on your DOMESTIC SIDE piping?

Or, do you somehow have an 'off line' filling system?

Maybe you have a private well and you are referring to the well pressure tank?

You need to take some pictures.
 
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Old 12-13-13, 09:04 AM
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Thanks for sticking with me.

The pressure tank/expansion tank has a faucet on it and water is supplied to the tank via a hose (connected by me) when needed. Obviously when the system is running right, no extra water is needed and the expansion tank holds what ever pressure reserve the supplied water left it at. I recently hooked up the hose to re-pressurize the tank when I decided to bring the system back up to pressure and I have been doing this to keep the system pressure from dropping below 12-15 psi while the air is purging.

I will try to get a few pictures today to satisfy your curiosity.

However, the pressure/expansion tank and FillTrol tanks are not the issue. Please re-read my initial post. I think since I called the tanks by the wrong name you got hung up on that.

1. I either have a leak in one of the lines.

or

2. Is is possible for the heat exchanger to have an internal crack that would have caused the condensate pump to pump out the system water?

Since no condensate water is coming out now, the leak/crack may only be leaking when the system is up to running temperature. Once I get all the line air purged, and the system not requiring any expansion/pressure tank water, I will be closer to proving this theory.

Until then, I am still assuming that I have a leak which has not been found. I am really just wondering if anyone has been here before and what other things it might look for or be trying.

Thanks
 
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Old 12-13-13, 09:54 AM
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I think since I called the tanks by the wrong name you got hung up on that.
Of course I did... that and the fact that you said you were running the tank at 70 PSI! To one who moderates a forum such as this where all levels of skill and knowledge could be posting, when I read something like that, all the 'red flags' go up. What you wrote SCREAMED " I DON'T KNOW WHAT I'M TALKING ABOUT AND TRYING TO SOUND LIKE I DO!" ... I'm sure you understand.

I now understand that you are running an 'off-line' system to keep your system filled.

Everything you describe says LEAK. I agree with that. Now all you need to do is find it.

You said that you have 'excess condensate' and it would seem from that information that your first approach at finding the leak should be at the boiler.
 
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Old 12-13-13, 10:21 AM
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Yes, I am still actively looking for leaks. Once all the air is purged out, any water the system calls for must be leaking somewhere. I am hoping with the boiler not heating, I will be able to spot the leaking water rather than it evaporating.

The extra condensate pumping I referred to was happening just before the system failure. This is what makes me think it is an internal leak in the heat exchanger. With the boiler not heating at all right now, I do not see any water coming out the condensate or any exterior boiler leaking either.

Once I get the air purged (less air than yesterday), and if the system pressure will stabilize (not calling for any more water from the pressure/expansion tank) I will then fire up the boiler and see if I get more condensate than usual.

At this point, I am scouring every nook and cranny looking for a leak.
 
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Old 12-13-13, 11:18 AM
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Leak of factory pipe (thin wall at bend) directly out of heater at about the 5 year point
Hi...Was this repaired under warranty of the heat exchanger?

I decided to bring the system back up to pressure and I have been doing this to keep the system pressure from dropping below 12-15 psi while the air is purging.
After you fill the external tank and fill the boiler shut the incoming feed valve to the boiler... Watch the psi without the boiler running or circulating.. You should loose pressure if there was a leak...

If you think its from the exchanger and only does it when firing from expansion, that may be true, but not sure with the way that aluminum exchanger is made...

If you have a lot of air but you know the water is circulating the vents should get it out...and no need to do a main purge..

I asume no backflow preventer...Where is the relief valve piped? In plain site? No water there...

I also assume that the extra condensate that you seem to be aware of is an issue since you have had the unit so long...

You could see more with the cover off. have you watched with the cover off and boiler fireing?

Those unites need maintainence once a tr of the exchanger inspection and cleaning... Cleans with a metal ruler looking device...

At a min I would get the kit and take it apart and clean it... You may find something...

383-500-605 - Weil Mclain 383-500-605 - Maintenance Kit for Ultra Gas Boilers (Size 80, 105)

591-706-200 - Weil Mclain 591-706-200 - Heat Exchanger Cleaning Tool w/ Handle

Page 93-96 or so here....

http://www.weil-mclain.com/en/multim...ler_manual.pdf
 
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Old 12-13-13, 12:16 PM
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Hi...Was this repaired under warranty of the heat exchanger?
No, the external pipe was not covered due to is not being the actual heat exchanger.

After you fill the external tank and fill the boiler shut the incoming feed valve to the boiler... Watch the psi without the boiler running or circulating.. You should loose pressure if there was a leak...
I will give this a try.

If you have a lot of air but you know the water is circulating the vents should get it out...and no need to do a main purge.
Much less air then when I started. Still a little air pinging through the system. Overnight the Feed tank dropped from about 70 psi to 35 psi with air purging. I am not sure how much water that equates to, but I am guess it a couple cups of refill.

I asume no backflow preventer...Where is the relief valve piped? In plain site? No water there...
Not sure what you mean by backflow preventer.
Relief valve visible and not leaking. I replaced it last year. Bucket under pipe coming from relief valve placed there after last bad valve has no water in it.

I also assume that the extra condensate that you seem to be aware of is an issue since you have had the unit so long...
Yes, the extra condensate was noticeable the day before the failure. It typically pumps a few times a day and a couple times in the night. Condensate pump was running more than normal, I would say every two hours the day before the failure.

You could see more with the cover off. have you watched with the cover off and boiler fireing?
With cover off, and boiler firing, I only have a postage stamp window to look through so little can be seen. No, I did not notice anything when viewing through the inspection window.

Those unites need maintainence once a tr of the exchanger inspection and cleaning... Cleans with a metal ruler looking device...
Boiler has had work every year since install, including three maintenance kits (exactly the one you referenced) over the last 9 years including one maintenance kit at the start of this season, installed by me. I inspected and cleaned the the heat exchanger and burner before winter, installed new igniter and replaced all the provided gaskets.

I may take it apart again and more throughly inspect the exchanger while I am waiting for the air to purge and look for a leak or odd corrosion. I will keep you posted.
 
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Old 12-15-13, 10:58 AM
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Update - Air Purged - Pressure holding

Air mostly purged by letting all zones run open and letting the Spirovents do their job. This took about three plus days.

Reserve water pressure tank that feeds the FillTrol tank went from 75 psi to 70 psi over the course of about 12 hours. System pressure at 12psi. Still no visible leaks from boiler or any of the zone piping. I checked every zone (6 times now) looking for leaks. Roughly 90% of piping can be inspected without cutting into drywall.

With the air purged, the system appears to be holding pressure nicely. If it holds today as expected, I am going to fire the boiler tomorrow and see if I get the more than normal condensate pumping and system calling for reserve water.

Right now I am leaning more toward there being NO leaks in the zone pipes and more toward a heat exchanger crack/leak that is only present when the boiler is at running temperature.

Of course, there could also be a zone pipe leak that is only present when at running temperature, but since I noticed the extra condensate pump cycles before failure, I am thinking it is the heat exchanger.

Weil McLain will certainly require a licensed tech to make the proper diagnosis before replacing the heat exchanger under warranty. But, at this point, the troubleshooting I have done should at least point them in the right direction.

Any additional thoughts?
 
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Old 12-17-13, 12:52 PM
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boiler leaking

Can you isolate boiler from system and then watch boiler pressure temperature gage to see if it looses pressure .
 
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Old 12-21-13, 12:54 PM
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Fired Boiler - Excessive condensate?

So, the entire system pressure (with boiler in the loop) held at 12 psi for 5 days and I decided to fire the boiler with a heating tech at the house so he could see the system and details and deal with Weil McLain if necessary.

BTW, previously isolated boiler and pressure also held for two days at 12 psi.

Fired boiler: Water feed tank that supplies the FillTrol tank started dropping in pressure from 70 psi down to 40 psi over the course of about 10 minutes. I then brought it back up to 70psi only to have it drop to 40 psi 4 more times in the course of an hour.

While the feed tank was dropping in pressure for the first time, the boiler condensate line was filling up rather quickly in my opinion. Had first condensate pump purge about 20 minutes into the run and the second and third about 10 minutes apart thereafter. So roughly 3 pump purges (1.5 gallons) in the course of 30 minutes. FYI, the water being purged smells like warm glycol. We are currently running mostly water only glycol left would be residual from system line purge 2 years ago.

Condensate pump is 1/2 gallon capacity: Little Giant 554421 VCMA-20UL 115-volt Condensate Pump, 1-Pack - Amazon.com

Technician left: The tech left and I proceeded to watch the system for the next hour. One more pump purge about 20 minutes later and then nothing for 2 hours. It actually seemed to be running pretty well.

Boiler got up to full operating temp 180 degrees and things seemed good. I turned ON the two baseboard zones (all in-floor zones were already on) and left it for a few minutes (10ish). When I cam back, I smelled glycol again and the condensate pump had just started running. Wrote down the time 4:30pm for this pump purge. Got a seond purge at 4:37pm and a third at 4:44pm and a forth at 4:52pm. So, two gallons of condensate in the course of roughly 20 minutes.

Boiler again got of to operating temp and cycled through burn cycles as it should keeping the boiler water temp between 160 degrees and 180 degrees. Again no more condensate purging for about 2 hours and all seemed to be running well.

Had a theory that around 120 - 140 degrees was when the boiler heat exchanger starts leaking. Turned the gas off and let the system cool down with all pumps and several zones still open, thinking I would see condensate purging as it cooled. It did not happen. Then I brought the system up to operating temperature again and again no condensate purging.

At this point it was getting late and I decided to turn the gas off again and let the pumps run overnight. Topped off the Fill tank that feeds the FillTrol tank at 72 psi and left it over night.

In the morning: Feed tank still at 72 psi and system still at 12 psi. Again, this is with the boiler in the loop but not firing as I turned the gas off. System pressure again stable like the 5 days prior to boiler firing. I have not fired the boiler today as watching the system has a way of eating up an entire day. 8-)

My Thoughts: I think I have an intermittent leak in the heat exchanger that only leaks at certain temperatures or when the RETURN water hitting the boiler is at a certain temperature. Not something I have been able to fully reproduce except to say that if I fired the boiler right now, it would likely purge 1.5 to 2 gallons of water in the course of 30 minutes. I may try this again, perhaps tomorrow when I have more time.

Any additional thoughts after hearing the troubleshooting data?
 
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Old 12-21-13, 02:23 PM
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Leaking boiler

Boilers are tested at factory usually at 50 psi. so I would find out what a safe pressure test would be , isolate boiler from system remove safety valve and cap pipe . Fill boiler with water and carefully bring pressure to test pressure. This will confirm integrity of boiler.
 
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Old 12-21-13, 03:07 PM
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And as usual, if you do a pressure test, follow Saves' advice and test with WATER PRESSURE, NOT AIR PRESSURE!
 
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Old 12-22-13, 12:31 PM
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Will call Weil McLain on Monday

I will call Weil McLain on Monday to see if they will provide me with a "Safe Pressure" number for testing the boiler and let you know how it goes.

Looks like I will have to remove the outlet pipe from the boiler and plug there as the closet shut off in-line is after the Spirovent and thus will likely bleed pressure off before a proper pressure test can be done.

On the intake I have a valve close to the boiler and that should be ok.

More later.
 
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Old 12-22-13, 01:04 PM
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I will call Weil McLain on Monday to see if they will provide me with a "Safe Pressure" number for testing the boiler and let you know how it goes.
You shouldn't have to call W-M for that information. You should be able to find it either on the boiler data plate, or in the boiler manual. Besides, if they have a clue that they are speaking to a homeowner, the call will be ended with: "Have your installer call us"... they won't speak to homeowners.

Look for a number with " MAWP " which is Maximum Allowable Water Pressure.

What is a pressure test going to tell you that you don't already know? The system holds pressure until you heat it, at which time you begin dumping huge amounts of condensate. You haven't found gallons of water pouring out of a leak in the zone piping. I think the conclusion can be drawn from this information.

Once again, I have to caution you... do NOT test with AIR pressure! If there IS a crack in the boiler and you pressurize with air, and that crack 'lets go'... KABOOM! There is a LOT OF ENERGY stored in compressed air! There is VERY LITTLE energy stored in water 'under pressure'... in fact, NONE. Water can not 'store' energy other than in the form of HEAT. (or 'altitude'...)

Yeah, I know... the "Myth Busters" 'launched' a water heater that was (supposedly) full of water... but that's because they HEATED it and the water expanded and exceeded the pressure rating of the vessel. And I sorta doubt that they did not have a tank full of air... it IS TV after all.
 
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Old 12-22-13, 01:42 PM
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Max Allowable Water Pressure

Yes, I saw that plate. It says the MAWP is 30 psi.

Thanks for the additional air warning. I have a spigot after the incoming supply to the boiler shut off and I would connect there with a hose hooked to city water (72-75 psi) to do the test (water only as I would be sure the hose is free of air before test). I would also VERY slowly open the valve/spigot as not to exceed the MAWP.

I will need a plug for the boiler out line and will not have time to get it till later in the week.

The tech who came on Friday is going to call Weil McLain on Monday and I will wait to see what they have to say about the situation after hearing the additional troubleshooting data.

I am with you and think that it is pretty clear the boiler is the problem, but "saves" was still encouraging a pressure test of the boiler. Wondering if "saves" is thinking Weil McLain require the test for confirmation as well.

I do have the first series (Series 1) of the Ultra boiler (currently up to Series 3, I think) and perhaps they have a know design flaw and will just replace the exchanger if it fits with know a issue/failure. Who knows.
 
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Old 12-22-13, 02:20 PM
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Boiler leaking

I saw that demonstration by the Mythbusters to show what could happen when a safety valve does not operate and why it is important to test yearly. The tank took off like a rocket because the heating elements where allowed to heat the water above 212f and when the tank split the water turned too steam , expanding 1800 times it volume in an instance .Air craft carriers still use steam to provide the power to launch air craft, we may see steam engines replace internal combustion engines .
 
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Old 12-22-13, 02:34 PM
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Well... depending on various factors, maybe not quite 1800 times, but certainly at LEAST 1600 times! And that 1600 times expansion is still an AWESOME amount of energy!

That 'flash to steam' is also the exact reason that one should NEVER EVER attempt to remove the radiator cap on a hot automobile engine! (or the top off an Espresso machine until it's cool... and DON'T ASK how I know THAT! but here's a hint... there's a dent in my kitchen ceiling! )

SDesign, a LITTLE bit of air should not be dangerous, but yes, try to bleed the hose first.

Also, remember that the temperature of the water is going to change after you fill with the cold tap. It will warm to ambient and in doing so you may see a pressure rise after you set it at 30 PSIG.

If the crack only opens when heated, the pressure test may be inconclusive.
 
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Old 12-22-13, 03:23 PM
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Boiler leaking

I think the 30psi. is maximum operating pressure and there should be a test pressure above the operating pressure , I have seen it stamped on the heat exchanger of a New Yorker steel boiler .
 
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Old 12-22-13, 04:38 PM
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Maybe... but I would think the wording " MAXIMUM ALLOWABLE ... " would mean just that. Wouldn't you?
 
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Old 12-22-13, 04:59 PM
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I think it refers to boiler operation, but if you want to prove the heat exchanger you need to apply the pressure that will not destroy a good unit but find the leak with cold or room temperature test water. To be safe check with the manufactory of the unit .The rule of thumb is twice the maximum operating pressure.
 
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Old 12-22-13, 05:05 PM
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Sdesign,
Check the Spirovent, I believe they all have a threaded portion so you can put a 1/2" cap on the vent. IIRC it even comments about system testing in the paperwork that comes with them. At least you won't need to remove piping to test.
 
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Old 12-22-13, 05:11 PM
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Leaking boiler

According to Science >Chemistry : Steam occupies a volume of about 1850 times that of the water used to make steam.
 
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Old 12-22-13, 06:25 PM
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Not wanting to 'HIJACK' another thread... but I have to take the bait... (sorry SDesign)

WATER at around boiling temperature at 14.7 PSI has a 'specific volume' of APPROXIMATELY 0.016 ft[SUP]3[/SUP]/lbm

STEAM at same temp and pressure has a specific volume of approximately 26.8 ft[SUP]3[/SUP]/lbm

If you do a simple ratio 26.8 / 0.016 , you come up with 1675 times the volume.

If you consider the actual conditions, such as pressure and temperature of the water before flashing to steam, etc, etc, you will come up with different numbers, but I don't think as high as 1850 ... do the math.

Tell ya what... let's make it real simple and use a ballpark compromise and say:


ONE CUBIC INCH of WATER becomes ONE CUBIC FOOT of STEAM. How's that work for ya?


According to Science >Chemistry
When you cite a source, at least make it something we can type into a browser... or look up at the library, or otherwise consult. That citation means nothing to us!

NOW.... if you want to talk about physics any further, would you please find the physics forum so we don't have to clog up SDesigns thread with more hijack posts?
 
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Old 01-26-14, 10:52 AM
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Final follow up

Just thought I would chime in and give the forum a conclusion to the boiler problem I was having.

It was an internal crack in the heat exchanger. Unfortunately, it was unpredictable enough that I was not able to duplicate it until it finally had a catastrophic failure.

The first heating technician that visited the house was not great and thus it left me with the option to either do a pressure test or prove my theory without it. Not sure a pressure test would have prove the failure due to the intermittent nature of the problem. Keep in mind that the system could run for a couple days with no problem, then all of a sudden drain the reserve tank. Then, it could run for hours sometimes days with not draining any reserve water at all.

So, I decided to only run the boiler during the day when I could monitor it. After about 12 days of making sure the feed tank was full and letting the system run normally, it finally failed to the point that I could see water squirting inside the firing chamber out of the side wall.

Once it reached this point, the system would no longer hold water even when turned off. The condensate pump would fill and then pump until the system pressure was at zero. Success!!

Called a different heating technician who came to see the failure and ordered a replacement heat exchanger under warranty. First heat exchanger lasted 9 years, but only ran without issue for one full winter, so it did not see nearly 9 full seasons worth of use.

Just thought I would share the outcome for anyone going through a similar problem with their boiler. Interior heat exchanger leaks can be tricky as they may open and close multiple times making diagnosis hard.

Thanks to all the forum members for their comments and suggestions.

Cheers
 
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Old 01-26-14, 12:24 PM
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NJT
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I was afraid that's what you were going to find.

Did they pro-rate the warranty? Have to pay labor, etc?
 
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Old 01-26-14, 01:51 PM
S
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According to the Weil McLain Ultra 80 warranty, up to 10 years the exchanger is covered at 100% & labor is not covered at all.

So, exchanger should be covered 100%, but I will have to cover the labor for installation and any extra stuff. We did a complete system purge and replaced all the system water and added conditioner.

They requested the exchanger be returned to them for inspection before refunding the cost of the new exchanger, so the heating company is out the cash until the verdict comes back.

The new exchanger came with new burner and face plate as well as new temperature sensors. I pulled the old exchanger apart and could not see the hole even with a mirror. I could however see the rusty colored streaking inside and the burner had similar streaking.
 
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Old 04-17-14, 09:59 AM
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followup

SDesign:

Thanks for the details of your saga. I have an WM Ultra 105 (series 2) that is approaching its 10 year mark, and I, too have a slow pressure leak that doesn't seem to be coming from anywhere outside the boiler. I looked inside and don't see any signs of leakage either. I was suspicious that when I had the pressure/temp gauge replaced that there was a small leak near one of the sensors, but don't see any sign of leakage there.

I suspect that exactly what you describe is happening to my boiler, namely that it only leaks pressure when firing, and leaks into the condensate line.

Did any of the pressure tests you did before the failure help diagnose this problem? And what steps did you have to take to convince WM to send someone to verify it and authorize a heat-exchanger swap under warranty?

I wonder how common this kind of failure is for these boilers? Perhaps any professionals reading this thread could comment on the longevity of these aluminum heat exchangers. I had my water treated several years after installation, as it wasn't suggested in the original manual, only in the maintenance kit.
 
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Old 06-01-14, 10:27 AM
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Check your dielectric unions

heater_man,

I have been meaning to reply for awhile, but have been quite busy.

The first tech that I had to the house did not diagnose the problem properly, even though all the signs presented themselves when he was checking the boiler.

I am not convinced that you have the same problem though. I noticed my condensate pump running WAY more than normal before the first major system pressure drop and this is what made me think it was an internal leak. Did this same thing happen to yours?

I did not do any pressure tests other than isolating the boiler via the existing ball valves which did not show any pressure drop. So, here is what I did.

Once I had all the air purged out of the system, I made sure the system did not drop in pressure using a hose (all air removed from hose before attaching using 2-way splitter ball valve) which was then attached to my autotrol feed tank. I had to add water to the autotrol tank, sometimes several times a day depending on how the how the boiler was acting. Other days I did not have to add any water. Fortunately, I work from home and could keep a close eye on it, otherwise I would have had to left the feed line turned on rather than manually re-pressurizing the feed tank every time. The boiler was always turned off at night as I did not trust enough to run through the night.

Long story short, the boiler crack finally opened enough that I could see water squirting inside the firing chamber and this is when I called the second heating technician to show him the same thing I was seeing. He was able to call Weil McLain and tell them what he saw and they approved a replacement core.

After the replacement core was installed, I was still having slight pressure dropping (different issue than the boiler leak) and I figured I must have an in-wall leak that was still undiscovered. Wrong! After warmer weather rolled around, the boiler was not running as much and I noticed that both my dielectric unions (where galvanized is joined to copper) were leaking. Both gaskets had been replaced when the boiler core was replaced as they were also leaking then as well. When the boiler was warm, no sign of leaking was present, but when it cooled down, the unions would leak. My unions when cold can leak about 4-6 oz a day each, but it does vary.

The dielectric unions may be a possibility for you to check out on your boiler. Again, when the boiler is running and warm, there is no apparent sign of these leaks as the fluid evaporates before there is any visual. I bet you have a slow leak close to the boiler and the dielectric unions would be where I would check first and then expand from there.

I hope this information helps you a little.

Cheers
 
 

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