Boiler water testing

Mgraymond

I have had two boiler failures in less than ten years - corrosion at the waterline. Does anyone know a good place to send water samples for testing? I have a VXT-120, but it's only been in 3 days - no water added so far.

nicholas bonham-carter

water analysis

maybe you can get the analysis from the water company.

are you certain that your system has no leaks? if you have a auto/over-fill, then i would suggest you cut off the water supply in the first several months of operation of the new boiler

was there any help from the boiler mfg. on these 2 change-outs?--nbc

Rod

Boiler Water Testing

Hi- Make sure that when you add "new" water to the boiler you bring the "new" water to the boil as this drives off excess dissolved oxygen which can be very corrosive.



For water testing I 'd contact Rhomar Water Management.

 http://www.rhomarwater.com/products/residential-steam-system/

They're very knowledgeable and are nice guys to work with.

- Rod

Mgraymond

Re: Boiler water testing

Burnham does not warranty corrosion failures. It's well water.

Mgraymond

Thanks

That looks like just the place to test my well water - thanks. I have an auto water feeder (VXT-120), so I can't use your advice about boiling the water, but it looks like good advice.

nicholas bonham-carter

Advice for the new boiler instalation

See if you can cut off the auto-fill, in order to see if there might be some water loss in the system, which could be as dammaging as bad water.--nbc

Hap_Hazzard

Makeup water

I noticed that Rhomar offers makeup water analysis in addition to the steam boiler water analysis. I would think you'd want to do both, as the agents that are causing the corrosion might not be present in the boiler water. Water analysis usually just looks at solutes, and many reactions form precipitates, so, to get a complete picture, you'd need to see what's in the water before and after it's gone through your system a few times. I know it isn't cheap, but I think it would be worthwhile in this case.



Also, you mentioned that you are using well water. If you have a water softener, you should be using the untreated water, not the "softened" water. You probably already know that, but since it hadn't been mentioned I thought I'd bring it up.

Hap_Hazzard

Bringing water to a boil

What he meant by that was adding the water either while the boiler is on or just before it comes on. A water feeder should only add water in response to a low-water condition, which typically occurs during a heating cycle, although usually near its end.



But this should not be the way makeup water gets added to your boiler routinely anyway. An automatic water feeder is a safety device to keep your system working in the event of a leak. Under normal circumstances, it shouldn't come on at all. You should be routinely checking your water level, flushing or blowing down the boiler and/or mud leg, and replacing any water you drain out while the boiler is still making steam. If you need to add more water than you let out, you need to find where you're losing that water (or steam) and fix it. Automatic water feeders are just there to keep you from losing heat in the event that water loss occurs due to a problem that develops between your routine maintenance checks. If you look at the VXT and it doesn't say "000" (or whatever it was the last time you checked) then something's wrong.

ChrisJ

Makeup water

I had contacted Rhomar about this a few months ago and they recommended doing a makeup water test.



I still have not done the test as I was able to get results from the town as I have city water. Hopefully they are accurate.



I would also recommend manually feeding the boiler water and immediately bringing it to a boil. Do not wait for the VXT to add water which is triggered by the LWCO.



I usually hop down / fall down my basement steps once a week and check my water level. If its 1/2" below the NWL I add some slowly then go up and raise the t-stat to get it boiling for 15 to 20 minutes.





And... I just noticed Hap_hazard explained the auto feeder already.

Mgraymond

Water Leak

Thanks, for all the good advice. The VXT added water today, so there is likely a leak somewhere, but it's going to be hard to find. I sent a sample of my well water to Rhomar for testing - what more could I learn by testing the boiler water?

crash2009

It's not that difficult

to find the obvious leaks.  Crank up the thermostat 4 or 5 degrees and do a radiator to radiator survey.  Don't fix anything during the survey, just write it down.  The most common leaks are:

1-radiator vents that do not close when the steam gets there

2-radiator shutoff valves that leak from the stem

3-the union between the radiator shutoff valve and the radiator

4-sometimes the radiator itself

5-check the main vents down in the basement too

6-while you are down in the basement, take a slow walk around and listen for steam escaping.  Most of the time the leak will be found in the worst place, such as the crawlspace, or behind 20 years of storage.



These are some of the places where you will find steam leaks.  Others might have more places to look. 

Mgraymond

Leaks

I found one small leak, from a radiator shutoff valve. It's a two-pipe system. I can't locate any air vents. There are both wet and dry returns. There are traps at the ends of the supply lines, and at the radiator outlets, but I can't find any air vents.

crash2009

Can we see

 a picture of one of your radiators?  Maybe a closeup of the adjuster or shutoff valve.  And down in the basement, is there any odd shaped cast iron things hanging from the ceiling?  Can we see a picture of those too?

Mgraymond

Pictures

All the devices on the radiators and the two in the basement were made by Dunham. There are no other devices on the pipes anywhere, and I think the basement things are traps - they don't have any orifices.

crash2009

You might have found your leak.

Most of what you have shown looks pretty good.  I was just comparing these two pictures.  The wood in the first pic is dry.  In the second pic it looks like the steam has stained it.  I would get someone to have a closer look at that area.

crash2009

Dunham System

I was just reading a couple pages on a few different kinds of Dunhams.  Some had the return trap.  They all had the "Air Eliminator"  Did those boiler boys run away with yours?  Here is a couple pictures of what it may have looked like.

crash2009

My pictures

 didn't turn out very well.  Here is the file that they came from (page 62 and 63)  I found the file in the library here.

Hap_Hazzard

Re: Boiler water testing

Actually, you probably wouldn't learn much from it (unless you wanted to calculate a blowdown rate or something equally obscure). The reason I said that both were important was that for some reason I thought you were only getting the boiler water tested, and I thought the makeup water was at least as important, not realizing that everybody was already working under that assumption. Oh well....

Mgraymond

Good eye

You're right, there is a little water leaking from the union of the second trap. How would you fix that, just try to tighten it? I don't see any signs of the air eliminators. The Dunham Steam Bible says they are used in systems with pressures from 6 to a maximum of 10 ounces. I wonder if my pressures should be that low? They are 0.7 - 2 pounds now, the lowest I can set my pressuretrol.

crash2009

Dunham with leaks

I wouldn't do anything just yet.  We are just in the discovery/investigate stage.  See if you can find any more wood that might be stained, close to the steam pipes.  Plus, it would be a good idea to have a few more sets of eyes looking at your system.  Could you post more pictures?  Need a shot of the boiler, show how all the pipes connect to it.  Stand back as far as you can. 

Mgraymond

Near boiler piping

The near boiler piping is all wrong, it's inherited from the 1915 coal boiler. It will be replaced this spring. There is a radiator shutoff valve with an obvious leak.

Rod

Durham Steam Bible

Hi Crash- Thanks for posting this link. This is one I didn't have in my collection. Love the drawings! ( and this was before Autocad!)

- Rod

crash2009

Yer Welcome

I thought I got it up in the library here.  Maybe not.

Dave in QCA

Dunham Systems

Hi,  I also happen to have an old Dunham system and mine also has been robbed of many of its original Dunham components as well.



On the Dunham system, such as yours, all venting of the radiators and mains takes place through traps to the return line piping.  I see the return piping in you photo of your boiler, and see that it drops over by the far wall.  Does it happen to empty into a condensate tank and pump?  If so, the tank is vented and that is where all of your venting occurs.  If not... we got a mystery!  I also see a pipe that goes up from the return piping, near the area where the steam pipe is coming over from the boiler.  The return pipe goes up, and then to the right. Where does it go?



Originally, your return piping would have been vented through an air eliminator.  You may have also had a return trap, it all depends on what pressure the system was designed to operate at.  In all likelihood, you may have only had an air eliminator.  It had a float in it that closed the vent port if water started to rise to the elevation of the AE.  This would have been caused by a slightly too high pressure in the boiler.  Remember, since the return line is not pressurized and is vented to atmosphere, that it takes 30" of water in the return line above the elevation of the boiler water line for  every pound of pressure in the boiler in order for the return water to flow into the boiler.  So, if the boiler has 2 psi, the return lines will fill with water up to an elevation that is 60" above the water line.   So, the system was probably intended to operate on lower pressure, or it had a return trap, that mechanically deals the pressure issue and pushes the water in with steam pressure..... we won't go into that now.



So, if you don't have a condensate return pump, you potentially have some big issues to address.    Just guessing on the difference between your return piping and the water line at approx 30", your boiler limit is 1 psi.  The only way to control this is with a vaporstat.



Also, if you don't have a condensate pump and tank with a vent, it leaves the question unanswered, how the heck is your system venting?  Well... some of the venting is taking place in the leak in that crossover trap.  BTW, that is probably loose at the union connection and could be tightened up to correct it.  You may also have minor leaks at valve stems.  Somewhere there is a enough air escaping from the system so that you are able to get some steam distribution.  I could just be by shear luck that it works at all.  I have actually seen a Dunham system near me that had the vent plugged.  It was working... sort of.  But when the vent was unplugged, the owner could not believe how much better it worked because of getting even steam distribution.



So, if you don't have a condensate tank, don't have any type of a vent on the return piping....    You need to install a vent!!!  If all of your traps are working and closing when steam gets to them, you can vent through an open 1/2" or 3/4" pipe.   It should be near the ceiling level, above the level of the lateral return piping.  But, if your boiler pressure goes up to 2 psi, you're going to have water pouring out.  So, in that case, putting a steam line vent such as a Hoffman 75 would be in order.  But if it were me, I would invest the money in a vaporstat instead.  If you got steam coming out, then you need to repair whichever traps are leaking by.



Sounds like you may have a system that has been botched up through the years.  This could not have helped the longevity of the previous 2 boilers.  However, all previous advice relating to leaks are certainly correct.  This is what takes out cast iron boilers.  Leaks above the water line are generally caused by water that has high chlorides compounded by a leaking system because the chlorides remain when steam or condensate is lost.  Then, when you add more water, the chlorides build up.  Imagine putting a pot of water on the stove and boiling it till it was almost dry, then adding more water, over and over.  You will build up quite a bit of lime scale.  Also will build up chloride levels and that is what seems to take out cast iron boilers at the water line.  High chloride levels in the boiler water, combined with the high temperatures of the cast iron that exists above the waterline are known to cause a phenomenon called graphitic corrosion.  That most likely what is going on.



It time to closely address and tune up your system or you are going to continue to buy new boilers.



Also, could you take some more pictures of the boiler close piping?  Different angles, up closer.  From the angle the photo is from, it does not look right, but then, we can't see it all.

Dave in QCA

Oil Fired?

What model of boiler is this?  Is it an oil fired boiler?  Have you already replaced it?   If it's oil, it would be the perfect place for a Burnham Megasteam.  The are warranted against corrosion.  Also, all of the fire surfaces of the cast iron are below the water level.

Mgraymond

Dunham Systems

There is no condensate tank or pump - it is a gravity return. That pipe is a connection from a radiator outlet to the dry return. I know there are lots of problems with the near boiler piping - equalizer in wrong place, no swing joints, bullhead tee, but a Burnham man came to visit and said those things needed to be fixed, but they would not cause a corrosion failure, leaks would. It's a Burnham V903 - they have already replaced the boiler sections.



Looks like I need a vaporstat and some air vents, and get the leaks fixed. Would a Mepco 1240 be a good replacement shutoff valve for my Packless Dunham?

Dave in QCA

Dunham Valve Replacement

Yes, the Mepco 1240  is the perfect replacement for your valve.  It is a packless valve that opens and closes is a little less than one full turn and it has an indicating dial as well.  I don't know how the cost of this valve compares to others, but this is a very high quality valve.  I simpler valve would also work, but there would be packing and a packing nut that would need adjustment from time to time.  Also, conventional valves usually require about 4-5 turns from off to full on.

Mgraymond

Vent Sizing - Two Pipe

The boiler is short cycling now, so I think I should add a main vent when or before I install a vaporstat. What size main vent? There are 16 radiators, the steam mains have about 13 feet of 3" pipe, 65 feet of 2 1/2", and 60 feet of 2" pipe. The dry returns have 30 feet of 1 1/4" and 100 feet of 1" pipe. Where should I put the vent? The short horizontal piece of newish looking pipe on the right side of the picture in the "Dunham Systems" post is the end of the dry return. It could be that is where the Dunham Air Eliminator used to be.

Dave in QCA

Location of old Air Eliminator

Yes, I think you have come up with the answer of where the Air Eliminator used to be.  My guess is that it was blowing steam, so someone took it out.  DUH! 

You need to install a vapor stat to limit pressure at a low point.  8 oz will probably work just fine.

You can install a vent station as I have crudely drawn.  If you want to protect against the possibility of steam blow by through a failed open steam trap, then I would install 2 Gorton #2 vents.  Together they will match the main venting that you have from your 2 1E crossover traps.   If you're not worried about steam blow by, either because you have already repaired all of your traps, or are going to repair them immediately, then you could simply vent through an open 1/2" pipe.  The air eliminator did not close against steam, only water.  You are going to control your return line water level by installing a vapor stat.