Dry Fire Failure? Water Feeder Options?

Fishin_Rod

Our steam boiler has failed due to 40+ leaks in the heat exchanger "buttons" on the combustion side of the boiler sections. (Dunkirk D247-400 that had replacement sections installed seven years ago.)

I talked to Dunkirk Technical Support about that failure mode. The tech said that was most likely due to "dry fire failure". That seems reasonable to me (non-expert), because I never liked how far down the water level in the sight glass fell during long heating runs on very cold days.

[The other option may be too long of run times? I would turn the boiler off at night, and then have it come on at 5:30 AM. On bitterly cold days, it would run a long time. (We do have a small forced air furnace in the attic that warms the upstairs bedrooms.)]

Our house and original boiler system was from 1918. That boiler lasted for 85 years! However, there was lots of "extra" plumbing in the furnace room. IMO, the company that did the new boiler installation were good plumbing/HVAC guys, but knew very little about steam systems. They ripped out most of the original plumbing and installed the new boiler as directed in the manual.

Unfortunately, the new system barely worked, so they had to hire a retired steam guy to come fix our new installation. I think he added multiple vents on the condensate return lines, a few check valves, and a Hartford Loop. The system operated much more efficiently after his "tweaks".

The old system did have a large "pot" (horizontal cylinder) of maybe 1.5-2 gallons of volume with an adjustable weight on a lever arm. I assume this allowed for adjustment of a float valve inside of the water pot. It was removed by the installers. I believe that component was plumbed into one of the condensate return legs? (But I am not certain, since I knew essentially zero about these steam systems at that time.)

Questions for the experts:

1.) Does a "dry fire failure" seem like a reasonable cause for my type of boiler section failure?

2.) How far down should the boiler water level fall during the longest run times of the season? I couldn't find any guideline in the manual.

3.) Did my original system have some type of "in cycle" water feeder installed to mitigate the effects of a low water level in the boiler? If so, is there some modern equivalent?

4.) My other problem may be our local, somewhat "hard" water. Do any of the experts think it is worth the time/effort to only run distilled water in the system? (My supply lines, return lines, and radiators are 107 years old. I will definitely pick up iron oxide (rust) in my lines and boiler during operations.

P.S. I did NOT have an automatic water feeder set up on our replacement installation. I wanted to monitor how much water the system was losing by the requirements for my tiny "hand feed" water squirts. When the replacement installation was new, I maybe needed one little squirt per month until it got really cold. And then only a bit more water during the coldest time.

Thanks for any advice or suggestions!

EdTheHeaterMan

Can you take some photos of the boiler and the piping around it. Your Dunkirk should have lasted much longer.

Questions for the experts:

1.) Does a "dry fire failure" seem like a reasonable cause for my type of boiler section failure?

YES

2.) How far down should the boiler water level fall during the longest run times of the season? I couldn't find any guideline in the manual.

I would like to see at least 1" of water in the gauge glass. it sounds like your LWCO is not operating properly.

3.) Did my original system have some type of "in cycle" water feeder installed to mitigate the effects of a low water level in the boiler? If so, is there some modern equivalent?

NO. The original coal boiler from 1918 had a hand valve for feeding boiler water, nothing automatic. The old boiler had a large "steam chest" where lots of water could be put into the boiler and that steam would lower the water line about 2 to 3 inches. By the time that happened the condensation from the radiators would be returning so the water level never got lower than about 1/2 way down the gauge glass

4.) My other problem may be our local, somewhat "hard" water. Do any of the experts think it is worth the time/effort to only run distilled water in the system? (My supply lines, return lines, and radiators are 107 years old. I will definitely pick up iron oxide (rust) in my lines and boiler during operations.

Most problems with water chemistry can be addressed with chemical treatments

P.S. I did NOT have an automatic water feeder set up on our replacement installation. I wanted to monitor how much water the system was losing by the requirements for my tiny "hand feed" water squirts. When the replacement installation was new, I maybe needed one little squirt per month until it got really cold. And then only a bit more water during the coldest time.

Probably not such a good idea.

mattmia2

Is this 2 pipe? Can you show us a picture of a radiator or 2 and an original radiator valve if they are still in place? It sounds like it is a vapor system that the previous installer butchered. You may need to do some things to keep the water in the boiler/let it return to the boiler if the original vapor specialties are missing.

Steamhead

For those not familiar, the Dunkirk D247 is the same as the Utica J series, currently in version F and called JF.

Most jurisdictions require CSD-1 controls on boilers this big, which involves two low-water cutoffs. But the D247/JF does not appear to have the proper tappings so the installer can use probe-type low-water cutoffs for both the primary and secondary controls, with the probes extending into the boiler section. These boilers have only one probe tapping- which is better than the Weil-McLain LGB, which has none- but the secondary has to be a float type, with moving parts and their inherent unreliability.

In a commercial application, generally someone has the responsibility to blow down the LWCOs. But on residential, many times the blowdowns don't get done. This can lead to dry-firing.

@Fishin_Rod , where are you located? And can you post a pic of a couple radiators (with covers removed)?

Fishin_Rod

Thanks for the comments, Ed.

"I would like to see at least 1" of water in the gauge glass. it sounds like your LWCO is not operating properly."

My LWCO was working properly (or at least "as installed"). I think the water has to go right to the top of the bottom brass on the sight glass holder before my burner cuts out. It would cut off during the day last winter as my leaks progressed and I was at work.

P.S. I did NOT have an automatic water feeder set up on our replacement installation. I wanted to monitor how much water the system was losing by the requirements for my tiny "hand feed" water squirts. When the replacement installation was new, I maybe needed one little squirt per month until it got really cold. And then only a bit more water during the coldest time.

"Probably not such a good idea."

I am not quite sure I am following your advice on this one. Is the "not such a good idea" not having an automatic water feeder set up to operate?

I fear that based on the steam volume that goes out to the whole house that the water feeder would add more water during the boiler water minimum during a run cycle, that my boiler water would be OVER the high water mark after the system returned to room temperature.

I take it you would advise having an automatic water feeder?

P.S. I do use Rectorseal 8-way for my water treatment. However, my system metallurgy and/or city water is so bad that it was hard to keep it the right color when I started losing some water from the first pin-hole leaks. That is why I was contemplating going to distilled water only in the system - which would be defeated by an automatic feeder on the water line. (Unless I can do a gravity-feed automatic water feeder from a reservoir of distilled water?)

Fishin_Rod

Matt,

Yes, this is a two-pipe system.

I will get some pictures of my radiators. I believe they are standard design. Steam goes in the top at one side, and exits at the bottom of the other side. There is a manual valve on the piping on the steam side. There is a steam trap at the condensate outlet. I have replaced a few of the traps over the years.

I do not know what you mean in your comment by "original vapor specialties". (I am a homeowner that is slowly gaining knowledge by observing and fixing my own system. You may need to expand on some explanations for amateurs like me to follow.)

EBEBRATT-Ed

For a boiler that size you must have a GIANT house. That boiler is usually seen on commercial jobs like church or school or apartment.

I would make sure the boiler is sized properly

We usually don't prefer to have condensate tanks or boiler feed tanks but its possible your large system may need one to work properly.

You could have plugged, or sluggish condensate returns.

I would like to see a water level higher than 1" in the glass while steaming. 1/2 a glass or the MFG recommended water level is the place to start. I wouldn't want it to drop more than 2"

We would need to know more about your system.

Fishin_Rod

Steamhead,

As you predicted, I believe I only have a single LWCO. It is a McDonnel & Miller – Float Type Low Water Cutoff.

I do blow it down 8-10 times over a heating season. The retired "steam guy" told me to do that. He said if the boiler water comes out dirty, then I should do it several times over the next week and keep adding a bit of make-up water until it showed clean.

I believe I did have my LWCO fail one time due debris (rust sludge?) in the float. I came home to add some water after the leaks started and the boiler was firing with the water BELOW the normal low cut off on the sight gauge. I went upstairs to check the temperature on the thermostat, and the boiler shut off while I was on the move.

I believe the thermostat shut down the boiler when it reached the target temperature. Fortunately, it was not a bitterly cold day, so I think I only ran a little while below the minimum water operating level. I did flush the LWCO a lot, and got it to return to normal function.

I live in Wichita, Kansas. Our city is much "younger" than the East Coast cities, so we do not have all that many old homes with true steam boiler and radiator systems. All of the public schools I attended were built in the teens and 20's and had steam radiators. I think we lost about 95+% of our local steam experts when the schools and most of the old homes converted to forced air. I do need to find a different installer for my repairs this time.

Steamhead

@Fishin_Rod , you might be able to sweet-talk one of us into coming out there to consult…………..

Jamie Hall

Can you show us a picture of one of the steam radiator INLET valves and any markings on it? We may be able to identify what this system was intended to be from that, as it's less likely that they have been "fixed" than anything else.

On water level. You may find, once we get things working more or less correctly, that the whole system will run better with the system cold water line quite near the top of the sight glass. Even as close as an inch or so from the top. There is no harm in that at all. As the system builds steam, the water level will drop, but even if it drops a few inches you will still be around the middle of the sight glass — which is where you want to be when the system is running.

You really should have two LWCOs on that boiler. One — the float type — can also be used to trigger an automatic feeder with delay and volume control, such as the VXT type, as well as shutting the boiler down on low water. The other should — in my view — be a probe type, set at the bottom of the gauge glass, which is a manual reset. That is, when it shuts the boiler off you have to manually reset it after you find out where the water went and refill.

And all that being so, you need to check the boiler from time to time — daily in colder weather — and add water manually to keep the water level where you want it in the gauge glass (which will be higher than the autofeeder).

mattmia2

It is also possible that the boiler is very oversized and contributing to your problems especially if the person that sized it didn't know stream and replaced the original coal boiler.

the correct way to size the boiler is by measuring the edr of the radiators. since it is 2 pipe you can size the boiler a fair bit under what you measure and have it work well as long as that is bigger than your heat loss. the actual output of the boiler(the rating on the boiler has a 30% pickup factor subtracted from it) being a bit smaller than the connected edr may help with your water level issues.

EBEBRATT-Ed

That boiler is around 360k input