steam boiler water...


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Old 11-11-02, 07:21 AM
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Question steam boiler water...

This is a quick one....

I have a 1-pipe steam system in the house I recently bought. I decided to drain the water out of the boiler since the weather has been warm the last few days in the Northeast before the weather turns cold for good. I drained about a gallon of water from the boiler (it was suggested on a previous post to drain the water in gradual steps to avoid possibly cracking the boiler by removing all the warm/hot water and replacing it with cold water all at once). I'd say the 1st 1/2 gallon of water was actually a black/purple color (unexpected) and then changed to a brown/orange color (expected). The overall color of the water drained is about the color of coffee with a touch of milk (aka somewhere between black and brown).

Since this house is my first experience with steam heat, I wanted to know if I should be concerned with the black/purple color of the water. Brown/orange I expected due to rust, corrosion, etc, but not black. The woman who lived in this house for the prevoius 10 years traveled a lot and probably just added water when it got low and never/rarely bothered to drain the boiler, so that may factor in to what's up with my boiler water.

At this point I'm concerned, but not alarmed. Please let me know if this is something I can ignore, or should take immediate action to prevent potential problems down the road.

Thanks

Matt
 
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Old 11-11-02, 09:29 AM
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There could be several reasons for the discoloration of the water and you are probably correct that the system was not maintained well. Chances are the previous owner had a boiler solvent installed, such as Squick, just prior to selling the home. This would also account for the color of the water.

It is highly unlikely that inside the boiler is rusting, especially one that has been in use. The brown colored water is a result of creating steam. It is the impurities in water such as chlorine, salt and minerals that is left behind in the boiler when steam goes upstairs. This is a natural process and the reason why you should drain your boiler weekly during the winter. This residue makes the water thicker and it cost more to boil as a result.

One should be careful when adding cold water to a very hot boiler for obvious reasons. Try draining a little water and then adding cold water and draining some more water from the boiler until the water comes out clear. It takes a little bit longer, but it is well worth it.
 
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Old 11-13-02, 04:55 AM
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I am in no way an HVAC expert, but I thought it was a BAD idea to drain your boiler too often. I was told or I have read that the new water contains impurities and oxygen that lead to rust and scale. Can anyone comment on this? Now I am confused.
 
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Old 11-13-02, 06:21 AM
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just a thought...

Homer J.

While I don't have a much (read-"any") experience with steam heat outside of what I've read and the help I've gotten in this forum (particularly from resercon), I believe that you're supposed to change the water in a STEAM boiler frequently. The idea being that clean water boils much faster than dirty water (kinda like it taking longer to boil soup than tap water - not my analogy, but it works for me). Quicker boiling saves money for obvious reasons.

Could you be thinking of a HOT WATER heating system? A steam system is always open to the environment via air vents, etc. so I don't believe that changing the water necessarily increases the propensity for scale/rust buildup. Plus, in a steam system you periodically have to add water anyways to keep the water level in the boiler sufficiently high. If you don't drain the water from time to time it's just going to build up all of the impurities left when the water is distilled/boiled inside the boiler. Changing the water will help flush out those impurities.

A hot water system, if I understand it correctly, is a closed system, so changing/adding water to that system is the only way to introduce more oxygen/impurities into it. Since the water just keeps re-cirulating I believe that unless you have a leak somewhere there's little need to add or drain water.

Now, I want to be honest that I have little experience with steam heat and none with hot water heat. What I've told you is base on a little knowledge, passed-on information, and a lot of deductive reasoning on my part. IF, IN-FACT, I'VE BEEN TALKING OUT OF MY ARSE, SOMEONE PLEASE CORRECT ME SO THAT I DON'T LEAD POOR HOMER J ASTRAY AND SO I MIGHT BE BETTER INFORMED THE NEXT TIME.

Homer, you could always ask Lisa or Flanders, but I think I'm actually on the mark with this one.

Matt
 
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Old 11-13-02, 07:04 AM
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Hey that makes sense to me. I have researched hot water systems to help make informed decisions on purchasing and maintaining. I have a 3 family with steam heat on one floor and hot water on the other two. I installed the hot water systems myself, but the steam was already there. I guess I should read more about how to maintain my steam heat as well.
I need the crayon removed from my brain again! (only understood if you seen last nights episode.)
 
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Old 11-13-02, 07:18 PM
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I have a little knowledge in boilers, both steam and hot water generators.

Once water is heated above 180 F, most of the oxygen is driven off. Oxygen is bad in a closed system. This is why you will find black iron pipe used on steam and heating system hot water systems (not to be confused with domestic hot water, like what you take a bath or use in your kitchen).
Blowdowns are important for each system, more so on steam as the water remaining is always becoming more minerally charged. Scaling becomes a big factor when this water is really out of balance. A hot water system use the blowoff to remove sediment from the boiler mudllegs, not so much as to remove increased hardness levels.

Without going into chemicals used for various reasons, I hope I cleared this up a little bit...probably made it muddier...but...

Hope this helps...
 
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Old 11-15-02, 11:19 AM
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A hot water heating system is a closed system. The only time you change the water in the system is if you have to purge air from it or have a repair done.

In a steam system, blowing down refered to removing the built up sediment from the low water cutoff. In these older boilers, it was a mechanical float type. So if the sediment built up it could keep the float from moving and allow the boiler to run dry thus cracking the boiler. It is a very common failure. New boilers have electronic low water cutoffs which use a probe and milivolt electricity to check the level of the water. When the level drops below the probe the circuit is open and the boiler won't fire. Skimming a steam boiler is firing the boiler and slowly adding water untill it reaches a high point. I usually remove the pressure relief valve and pipe it to a "metal" bucket (not plastic). This heating of the water and slowly removing just the top layer of water helps remove oils and other floating debris which cause a system to surge (look at your site glass, the water drastically moves up and down while the boiler fires).

Adding new water too often alows dissolved oxygen and minerals to attack the cast iron sections, shorting the life expectancy of your boiler, and sometimes the warrenty.

I hope this helps to clear up this topic.
 
 

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