Rusty water

KH

Hi.  We are going to convert from oil to gas. Right now we have a not so old (maybe 10-12 years) steam boiler.  The little glass valve that shows how much water remains shows very rusty water and has for just over a year when we did some renovations (including moving and adding a radiator and remodeling and adding a new bathroom.)  I tried to drain it through the drain valve on the boiler, but was there for hours with no change.  Now that we are getting ready to replace the boiler and convert I'm wondering if there is anything else I need to do.  Could the rust be in the pipes??  Thanks in advance for your help!!

gerry gill

Chances are that the boiler itself

 just got muck in it..there will be plenty of water cleaning taking place with the new boiler..however i would recommend flushing the wet returns, or replacing them if its in the budget at the same time you do the boiler..if you don't have wet returns then you don't even have that worry.

Hap_Hazzard

Rust is normal

When you have water in contact with a cast iron boiler and steel piping, rust is inevitable. It's one of the reasons steam furnaces don't last forever. There are a few things you can do to maximize the life you get out of it though.



For one thing, when you fill a boiler with water, you should be ready to fire it up and either make steam or skim and flush the system until it's clean and then make steam. It's important to let it run for a couple of hours because it drives all the oxygen out of the water. Rust, after all, is what you get from the oxidation of iron. You can't keep oxygen totally out of the system, but you can keep it to a minimum by heating water immediately after adding it.



Water also facilitates rust by dissolving the surface rust as it forms, preventing it from forming a protective layer, but once the water becomes saturated with soluble iron compounds, this process, too, is limited. Unfortunately, not everything stays in solution, and a thick layer of sediment tends to accumulate in the boiler and the return piping. If it isn't flushed out periodically, it can build up and make the transfer of heat from the burners less efficient. This not only makes the water boil more slowly; it also lets the heated surfaces get hotter, shortening the life of the boiler and sending more heat up the flue. This sediment can also plug up your drain valve, pressure relief valve, gauges and low-water cutoff.



Clearly you have to let some water out in order to get rid of the sludge, but keep it to a minimum, and make it effective by using full-port ball valves to drain the boiler and the wet return. You can open them quickly and close them as soon as the water turns clear, purging the majority of the sediment while wasting very little water in the process. And, of course, you should replace the water and then run the boiler immediately. (Some people prefer to flush the boiler while it's running, but I prefer to let everything settle.)



If you have a float type low-water cutoff, you need to flush that too, and here the consensus is that you should blow it down while steaming.



I've really just scratched the surface. There is a lot more to understand about steam heating systems, and the best source of the most authoritative information available in a single source is We Got Steam Heat, available here. Just click on the "Shop" tab. If you want to delve deeper, take a look at The Lost Art of Steam Heating. The information in these books can save you money, but personally, I love it because it's just fascinating.