Draining for the Summer

TeachMeSteam

I know this question has been asked before but I am starting to think that among the options discussed, one stands out clearly better than the others. I just read a paper about wet and dry pipe fire sprinkler systems. And apparently the dry pipe goes through a bit of corrosion at the low points due to condensation that forms at the same spots throughout the system. As such, they mandate that all pipes are sloped with other measures that will bore you. Yet, they still experience a great deal more corrosion than the wet systems.

On the other hand, air pockets that get stuck in wet pipes apparently will do quite a bit of damage. What happens is that the air pocket stays in the same exact position, full of oxygen. As a result, the water line will create enough corrosion to leads to leakage/bursting in the pipes. Apparently, they are experimenting with nitrogen systems that help with these problems but that's a different matter.

With the facts above and what we know about steam, I think it's clear that draining the system in the spring would probably be the best bet. Why?

1. I am betting even after a week, the air above the water is full of oxygen as air slowly becomes oxygenated through the main vents. The oxygen will eventually reach the boiler. The water will therefore at the top will be fully oxygenated at come point. Raising the water level and boiling off the oxygen is a good option but you're basically simply pushing off the time when oxidizing of the metal starts as well as the position of the corrosion at a higher water level. (I guess you can keep switching up the position of the water level every summer is a good idea so you can even further extend the life of the boiler (if you can peer into the interior of the boiler).) Yet, at the end of the day, you are still experiencing full corrosion at work at the water line after a week or two for the full summer/fall.

2. However, if you drain the system, you should open , not close all the valves up. You might get some light condensation once in a while and a small pool of water at a low point. That's true but that pool of water will evaporate in a matter of hours. No significant corrosion will happen then. The only problem I see is if your boiler is located in a humid location and you experience light condensation more than occasionally which would always end up being the same pool of water at the same exact location. Even then, I don't think it would play a big part unless your basement is humid. If it is humid and if you want to feel safe, you can set up a weak dehumidifier next to the boiler.

I say weak dehumidifier because you don't have to waste all your money to get the entire basement dry. (Only if you want to for mold and fungus reasons. ) You only need to get the area around the boiler dry. Even those normal-sized dehumidifiers take a great deal of money to run. They are exactly a window air conditioner except the hot air escapes into the interior (unless you have ones that pipes to the outside.) I would get the smallest one. I would put it next to the boiler and have it run constantly to dehumidify the air around the boiler. That way, it will dry up any light condensation that might result near the boiler. The dehumidifier would need a drain that drains the water into a nearby sump pump.

I'm assuming that this would be by far the most economical and safest way to prepare the boiler for the summer. What do you guys think?

If this is the best way, I think these cast iron boilers should be designed so that the water slopes to a low point that drains like in the dry pipe fire sprinkler systems.

gerry gill

around my parts, the off season isn't long enough to warrant doing anything. But if i were to do something, i would press up the boiler by filling t the point higher than the header. You will have to do some experiments and perhaps video inside the boiler to determine the effectiveness of dry draining it.

EBEBRATT-Ed

I agree with @gerry gill flood the boiler. Run the boiler until it starts to steam with a normal water line and then shut it down. Add water to flood the boiler up into the header. (add water very slowly). Disable the boiler so it cannot be started.

Make sure to drain it down before firing

bill714

why not just fire up the boiler say once a month and bring it to a boil. wouldn't that boil off the oxygen?

TeachMeSteam

First, firing up once a month is sort of a pain in the butt. There are so many things that goes off in one's life. I think simplifying things are key. "Set it and forget it."

Second, I'm assuming that the water becomes oxygenated faster than one month. The air above the water is full of oxygen after cool down; I'd assume that constant equilibrium exchange between the water and the air would oxygenate that water (at least the top 1/2'', the only important location) pretty fast. Perhaps, an engineer can chime in.

bill714 said:

why not just fire up the boiler say once a month and bring it to a boil. wouldn't that boil off the oxygen?

TeachMeSteam

I think that's a good idea. I'd rather have the header get replaced than the boiler sections. It would be much cheaper.

But I'm thinking that if you do it this way, it ends up being cheaper. Even a small dehumifier set at a slightly higher humidity does cost a lot of money every month ($15-30/month) but that would be only for about 6 months or so (about $100?/year.

Compared to replacing the header say every 20 years?

Tough call.

Just increasing the water level to the header would be a lot easier than setting up a dehumidifier and draining, I admit.

I don't know...I wonder what other considerations need to be made.

What I did realize though is that if steam companies that still make steam systems designed their boiler sections so that all the water would slope down to a single lower water drain, that would avoid all this. (I hope they are listening.)

gerry gill said:

around my parts, the off season isn't long enough to warrant doing anything. But if i were to do something, i would press up the boiler by filling t the point higher than the header. You will have to do some experiments and perhaps video inside the boiler to determine the effectiveness of dry draining it.

bill714

This may or may not be possible but if you close all the valves to the boiler hook up a vacuum pump, pump all the air out so no air no oxygen
no rust

Jamie Hall

Firing up once a month to dry things out on the fire side is a pain? Say what? Do you have or can install a seven day programmable thermostat? If you're concerned, set that thermostat to fire the system once a week for half an hour and then forget the whole problem. Set it to run while you are in church, or out golfing,, or whatever.

EBEBRATT-Ed

Look at it this way.

With water in the boiler at the normal water level the entire surface area of the top of the water is exposed to air. Flood it into and above the header and the only surface area exposed to the air is the area of you steam supplies coming out of the header. You need to keep the boiler wet. Dry shut down can be done but it's not worth what you have to go through