Should a steam boiler be drained in the spring or left wet

I have a steam boiler. Should it be drained & left dry for the summer or left wet

no

Hi Ed,

I'm not sure how bright your bulb is either, nor do I want to know, however you have the right answer.

Do not drain the boiler "for the summer". To refill it would add fresh water to the system. The idea is to keep fresh water make-up to a cast iron steam boiler to a minimum, since it contains all that stuff that is bad for boilers.

If the sediment in the bottom of the boiler is especially thick and needs to be flushed out, then that is a good reason to drain and flush the boiler. But to drain the boiler just because it is the off season, then that is not a good reason.

Best regards, Pat

I really dont know much about light bulbs , but if you are not using your boiler for domestic hot water , drain it , and take the smoke pipe down , open it up as much as possible , clean outs etc . Let the air into it .You will get a small amount of surface rust , but this is better then Rot Dave F

Here's what our service man has said about summer setup ... we no longer use the hot water part of the Burham V 74 so he has set the furnace to keep the water in the boiler around 112 degrees, says this will keep the joints from opening up?? Whether this is true or not thats the way he has it set, is it worth it ?? What are your thoughts on this?

We meet up with forced air again - in a pyramid, no less

In spite of the many ill some people say of the content of a steam system, I find there really isn't anything wrong with boiled water, what is bad - real bad - is all the noxious air we expect our boilers to live with.

Fresh air is bad. Fresh water is just as bad.

Flushing the boiler and filling it with new water just before sending it off for summer vacation would be a real bad idea unless you make sure you treat the water with all the anti-corrosion and oxygen scavenging additives.

Draining sounds good but it is only as good as how well you can dry the innards of your boiler. If there remains a puddle, then your efforts are no good because the inside-the-boiler air will contain the perfect moisture for allowing corrosive oxygen to chew away at your iron.

For acceptable dry summer storage, you need to be able to insert a cartridge of dessicant inside the boiler and you have to be able to open at least several holes (hand holes and such). Not easy to do for just a 6 months break, but a must for anything longer.

I've also heard about dangling a light bulb (a bright one...) into the dried water cavity and keeping the light on for a little warmth. Maybe? Seems tedious.

Muck dries up too. What was easy to handle mud during the heating season might become a calcified clog once dry.

So, the lazy way of just doing nothing until the heating season starts again isn't the worse one. Isn't that cool?

Some easy improvements to help the boiler: go for sequestration.

Air is the bad stuff you want to keep away. It comes back in into the system via the air vents. The radiators and the piping survive OK because they dry themselves good enough on cool off.

Removing the air space in the boiler by filling it with water is good, but you either have to boil this water or add chemicals to it.

And to keep the air from going into the boiler in the first place, just shut all valves to it. Label them as shut so that you won't forget to open them again. Sadly, many boilers don't have a king valve.

Adding chemicals for the summer is a very good idea, as Tony mentioned.

Next,

Keeping the boiler set at any below boiling point temperature for the whole summer is an expensive waste of energy. It might have some benefit for keeping dissolved oxygen out (not real sure) but the really bad thing it does is to cause you to add quite a bit of fresh water throughout the summer. With the slight simmer, you'll still be evaporating lots of water, and it will be free to leave the system since you don't build enough pressure and heat to activate the steam trapping mechanisms in your air vents. And you'll add fresh water through the automatic feeder... fresh... not too good an idea.

The same problem is true with a domestic water coil summer boiler operation. I find domestic water is best left to it's own appliance.

We don't want either fresh water or fresh air to foul up our lives, do we?

Anecdotal evidence.

We once had a 1 1/2 return that had been abandoned because of a change of plan. This pipe had had 30+ years of service as a dry return before it was capped off at both ends. After that, it remained half full of condensate for the next 20 years. When I opened up this pipe like a common tomb raider breaking into the pharaoh's secret crypt, my big surprise was how well the pipe kept up. I was surprised to even find water in there. A simple flush and the return was plenty good enough for reuse. None of the threaded fittings were even hard to unscrew. I've worked with pipes that were in open humid environments for less time than my 1 1/2 return that were simply impossible to revive, but these weren't on a steam system... aaah.

My conclusion is that keeping things sealed off from air is a perfectly acceptable method of preservation, whether condensate is present or not.

Of course, breaking into this sealed off pipe came with a inescapable curse: steam went through my brain

Hey, I think it's time to stop and get a breath of fresh air.

May our boilers have a nice summer vacation.

My father (RIP) was telling his customers the exact thing back in the 60's.

For my Snowman built in 1910, (the good old days when the cast iron was an inch thick) oxygen is the coconspirator of rust! This boiler is 100 years old and going strong! Overhauled piping in 2023. Fresh water contains more oxygen. Blow down the boiler (still uses a float LWCO [new in 2023]), and leave the boiler filled. Do NOT add water which also adds oxygen. I put in a quart of Black Swan during the heating season. The two-pipe system ONLY has vents (two Watts SV-3) on the return line in the basement. No air is vented at the radiators. Any stinky air that the system does vent is vented to the boiler room(combustion room) which has a fresh air intake.

Here are all of my opinions on this topic, which I have thought about many many times and done several interesting experiments (and thought experiments).

• First, you should have boosted pH in your boiler water to 9-10. When you have this, corrosion at and below the waterline is very very low. But we know that boilers never rot out at or below the waterline…they rot out at the top of the steam chamber. More on that later.
• Some respondents gave the reasonable-sounding advice to fill up the boiler. The reason this sounds reasonable to me is because, if your pH is where it should be, that will greatly reduce off-season corrosion in the entire boiler. But is off-season corrosion the cause of boiler failure? I don't think so. If it were, then why doesn't the header rot out?
• For those "fill it up" folks, they often warn to heat up the boiler to drive out the oxygen. This also seems reasonable until you think about it more. Every time water is added to a boiler during the heating season, it is almost immediately heated up which drives out the oxygen, and yet still boilers rot out. And boilers with a lot of makeup water during the season rot out much faster, we all have seen. So it seems to me that it doesn't matter if you drive out the oxygen…the act of driving it out could be putting it into the steam chamber where it attacks the cast iron there, in the place where we always see boiler holes!

So what should people do? If you have a way to add water manually to your boiler, such as skim piping, then you can heat water on the stove top and add that to get the water level at the highest operating level you feel comfortable with (different boilers can handle different high water lines without surging).

If you don't have a manual way, I would just fill it to about that same level and not worry about heating the boiler to "drive out the oxygen" (or just leave it where it is at the end of the season). As I said, and as I think we all know from the photos of rotted out boilers on this forum, the waterline never gets a hole. Under the waterline never gets a hole. It's always the top of the section that gets a hole, so driving the oxygen out isn't helping anything.

By the way, this is an old thread, but that's OK.

Perhaps the big issue is adding chlorinated water which then sits in the boiler, drives the chlorine out (because the boiler and old water are very hot) but the corrosive gas just sits there in the empty space above the water line corroding things.

I add water and try to run the system immediately, my reasoning is this will push whatever gases that get driven out of the fresh water out of the boiler and out of the system instead of them lingering.