Seasonal Shutdown Procedures

cubicacres

We're almost ready to shut down our WMC EG-75 single-pipe steam boiler for the spring. When we fill the water a few inches extra to raise the water line to prevent rust-out & run the boiler for 20 minutes to dissolve the oxygen, is there any issue with running a boiler with a few extra gallons of water above the usual gauge glass level (maybe 3/4 up the gauge glass instead of around half up the glass water level as usual?) Somewhere I read over-filling a boiler can be as bad as under-filling, it, but don't remember the specifics.

nicholas bonham-carter

I would say that filling up the boiler for a summer shutdown should raise the waterline to the header.
Run it until it begins to boil, and then shut it off at the switch. Put a note on the switch to remind yourself to lower the waterline before the first winter firing.
This assumes that you do not plan any summertime maintenance work which will require draining the boiler again, such as cleaning the pigtail, LWCO, gauge glass, or installing a new vaporstat, low pressure gauge, etc.--NBC

cubicacres

Since we have two 3 inch risers connected to a 4 inch drop-header (see my avatar photo of our boiler prior to insulating), would this mean filling the water until it spills into the 4 inch header pipe? Is there a way to check what the new water line is at that point, or do we just add 8-10 gallons or so and estimate where the water fills to?

The Steam Whisperer

Our procedure:

Complete all annual water side maintenance....cleaning controls, bottom of boiler, blowing down return line,etc and make any repairs. Add water treatment according to manufacturer's instructions. We Use 8-way and I believe they recommend doubling the normal treatment level for summer lay up.
Refill until water is up into risers ( pipe will turn cold with a cold water fill). Also the pressure gage will read the increased head pressure over the gage...each 1/2 psi or 8 ounce = 14 inches of water above the pressure gage connection to the system.
Bring water to boil and then shut down and place conspicous posting about draining water level to normal before start up. The extra treatment concentration may need to be diluted after fall start up. Usually the boiler will need a few blow downs after running for a while in the fall because of rust returning off the system.

MilanD

Question on expanding property of water: if you fill the water to the header, then fire it to boil, it will send the water up the main by shere fact that water expands when heated. When I did a cleaning and did this, our LGB 7 didn't like it one bit. Anyone else had this happen? I measured the temp, and could not safely get the water past 180*F.

nicholas bonham-carter

It only really expands as it changes to steam. When an over full boiler makes steam, there is a bit of water hammer as the bubbles rise up into the header.--NBC

MilanD

> @nicholas bonham-carter said:
> It only really expands as it changes to steam. When an over full boiler makes steam, there is a bit of water hammer as the bubbles rise up into the header.--NBC

From what I observed, bringing to boil of a overfilled boiler in order to get the O2 out will result in a lot of water getting sucked up the main. Knocking is quite violent. Our boiler is piped to spec, so no issues there, but phew- wouldn't want to do it again.

For this reason, getting the waterline up or down by few inches and then cooking off the O2 should be equally effective. Imho. I agree on 8-way or extra steamaster for summer storage.

The Steam Whisperer

I believe getting the water above about 140F to 150F should be good enough to drive out oxygen, especially if you get violent banging when trying to boiler when overfilled. Most people can't gage water temp well just by touching the pipes, so boiling is easier to tell.

MilanD

I let out a pint down dran/blow-down valve and stick in a thermometer.

cubicacres

Thanks for the suggestions. I was nervous about cooking that much water (how would the 15 psi safety pressure release valve on top of the boiler behave under new higher water line, water leaking out of near-boiler piping, etc.)

Is one theory that if over the summer a few inches of evaporation occurs over time, better to have the new water/rust line in the risers instead of the boiler itself?

MilanD

Well,

According to this article from Dan - unless I'm reading it incorrectly - steam boiler is to be drained and dried? Fred comments that this leaves the boiler open to more rusting and offers a comment that also makes sense... This is where having king valves comes in handy. Keeps all the evaporation in the boiler, and closes it off from the atmosphere.

https://heatinghelp.com/systems-help-center/what-do-to-with-boilers-during-the-summer/

At any rate... I thought I should just add to confusion.

Fred

@MilanD , I'll be interested to hear other opinions about draining a boiler completely for the summer. I wouldn't do that to mine because you simply can't dry it out. The moisture will cause corrosion over the entire interior of the boiler. Even if you were able to completely dry the boiler out, remember there is still moisture in all the piping. I'm curious though what others think???

BobC

Draining the boiler would lead to increased corrosion. Overfill it some and bring it up to temperature without allowing it to boil to drive off the oxygen. The other option is to bring the PH up high enough so corrosion is inhibited - there will still be corrosion above the water line but the rooting at the waterline should be inhibited.

Bob

MilanD

Fred said:

@MilanD , I'll be interested to hear other opinions about draining a boiler completely for the summer. I wouldn't do that to mine because you simply can't dry it out. The moisture will cause corrosion over the entire interior of the boiler. Even if you were able to completely dry the boiler out, remember there is still moisture in all the piping. I'm curious though what others think???

I think best bet would be flooding then cooking the boiler, and then closing off king valves - you essentially turn the boiler into a hot water boiler for the summer (closed system), by flooding it and blocking off air infiltration. If this is not possible, next best thing is to raise water level, add chemicals (02 scavengers, 8-way or extra steamaster) bring it to 180*F, then and leave it be.

As always, the answer is - it depends, huh?

PMJ

My Bryant manual from 1956 says don't drain it each season and that no chemicals are needed except in very unusual feed water conditions. Seems to have been a good plan at 61 years and counting.

To me if fresh water is the enemy as has been stated many times on this site then it would follow that the less new water added overall the better. Overfilling my boiler for the summer with its big steam chest would be the biggest add of my season by far and might be 10 times what I would add in a normal season. I'll stay with minimal water additions and just leave it as is. Since I always leave the fill valve closed except when I choose to fill I expect the water line is never exactly in the same spot anyway.

I do run the standing pilot all summer which keeps it slightly warm in there.

cubicacres

Thanks for the link to Dan's article & other suggestions. Maybe adding another steamaster tablet & raising the water level a few inches with 3-5 gallons of water before firing it seems like the easier way to go, unless we tried raising it up to the risers with 10-15 gallons of water.

Other than water hammer with that 10-15 gal of extra water up to the risers, any other potential problems with that much water on a boil?

MilanD

> Other than water hammer with that 10-15 gal of extra water up to the risers, any other potential problems with that much water on a boil?

From my experience, water can be sucked up the main. Without steaming, most will stay in it. I settled for 1-2 inch water increase + Steamaster tabs and a quick boil to just under steaming point to drive out O2.

Weil McLane suggests new water add of 5-6 inches above the regular water line, and boiling off O2 for summer storage ONLY if chlorides content is over 400 ppm and overall hardness is 1,000+ ppm. Chem treatment is to be considered if chlorides are at 30ppm (and from what I've been seeing here in the Wall, that's pretty much everywhere nowadays). See attached.

To @PMJ 's point, he has an older and thicker boiler, so his logic is spot on for his boiler. With the reduced water quality in most municipalities, in terms of boiler use, less new water is the best plan. He has water in there that's from 25 years ago, so why needlessly add new water that's of poorer quality?

MilanD

One last thought: I don't think the boiler itself can rust out - I'm talking rust itself above or below the water line. Graphitic corrosion or at wherever the TDS buildup starts inside the boiler wall is another story. Regular rusting process usually forms a thin film, and then arrests the further corrosion. This is why the idea is to move the regular water level up or down when boiler is off for the season, away from line where water and air meet during the heating season.

Now, TDS and chlorides on the other hand create blistering buildup on surfaces inside the boiler, anywhere, which then cause overheating and other chemical/electrical reactions that create pinhole leaks which we call rusting, but it's really graphitic corrosion - so not regular corrosion. Likes of this I saw in my LGB in its 7th winter.

Thus, raising water level is the best solution imho, ro avoid regular rust-through at the water line. Then, adding some extra chemicals, and then cooking off the O2.

Then, during the heating season, keep controlling the TDS introduction through minimizing make-up water (keep an eye on water loss!), add chemical treatment (8-way, steamaster tabs, etc, or even distilled water itself - here, definitely add chemicals as distilled water is low on pH and attracts CO2 and O2 -, or go for Rohmar's boiler water. In the long run and going into the future, from what I've observed here on the wall, the trick to boiler longevity will be controlling water quality as it seems to be getting worse everywhere, and water quality control will have to become one more thing steam people start doing regularly.