Rust in Boiler Water

Dave_127

I have a 1-pipe steam heating system in my 60-year-old house.  Ten years ago, we added a room to the house and the contractor added a hot-water baseboard heating loop off of the boiler to heat the room.  Things have been fine until now.



A month ago, I was replacing a steam vent valve on one of the steam convectors and broke the valve.  I had to hacksaw it off to replace it and I believe that the vibrations kicked a lot of rust loose from the inside of the steam pipe leading to the convector.



Now what I am experiencing is that the hot water loop recirculator pump and TACO check valves keep getting clogged with rust.

- The check valve at the end of the loop has stuck open a couple of times.  I cleaned it each time.

- The check valve at the beginning of the loop has stuck closed a couple of times.  I cleaned it and finally just set it to always be open, letting the other check valve do the work.

-  I've gotten air in the hot water loop, which I think is either from the pump cavitating when the feed clogs or the check valve just above the pump clogs, or steam is forming in the hot water loop pipes.



So now I am flushing rusty water from the low-water-cutoff valve and from the bottom of the boiler once or twice a day (morning and evening) and topping off the boiler water each time.



I am also wondering if rust is trapped in the bottom of the steam pipe loop in the steam return and keeps getting fed back into the boiler.  (I forget the name of that loop.  It is the one that goes above the boiler water level and down again right before the return line enters the boiler.)



If I added boiler conditioner to the boiler water, would it help me take out the rust?



Anything else I should try to do?



Thanks,

Dave

nicholas bonham-carter

cleaning the system

there is no magic potion which will dissolve rust particles in the system without also dissolving the iron in the boiler. there are various chemicals which can reduce the rusting, but once the rust is there, you can only continue flushing it out.

there are strainers which could filter out the rust particles, when placed in the right part of the loop. in addition, a magnet on the pipe in a place you can flush separately could keep the rust in one easy to clean spot.

until you have one, keep on flushing!--nbc

Dave_127

Helping Get the Rust Out

I've been considering taking off the main air vent valve and pouring in water to help flush out the rust that is sure to be in the bottom of the return loop.  (I think that one reason I am able to flush rust out every day is that it is slowly making its way from the bottom of that loop into the main part of the boiler.)



Any thoughts on whether this would help and if it would be a good or a bad idea?



Thanks!

Dave

Chris M_2

Rust in Boiler Water

Pouring water in is an OK idea.  Attaching a hose bib to the threads where you removed the main vent and sending a blast of clean water through the main, while simultaneously drain the boiler is a better one. 

Dave_127

Hose Bib

I'll have to see if I can find a fitting that will take me from a hose to a 1/4" NPT (which I believe is on the vent valve).



If I go the hose route, I may wait until after the heating season rather than run a large blast of cold water through a hot boiler.



Am I doing any damage by adding fresh water every day when I drain off the rust?  I'm thinking about how acidic (or not) the fresh water is compared to the boiler water.

nicholas bonham-carter

flushing returns through the main vent

if your main vent has a 1/4 connection, it is too small to be of any use, why not see if you can put a proper-sized one in while you are going to this trouble!--nbc

Dave_127

Main Vent Size

There is a nipple taking the main vent size down to the 1/4" NPT.  I don't know the size of the larger end.



I have no idea how long the nipple has been there or how hard it might be stuck on.  I don't remember if I saw any pipe dope on the threads.  I'll have to look tonight.



After breaking off the convector vent valve (the event that started this wonderful journey), I am now afraid of causing damage when trying to fix things.  If the nipple comes off relatively easily, I'll replace the main vent valve with a larger one.  Otherwise, I'll just let it go or maybe get the oil company to do it in the fall when they come for the annual burner tune-up.



That all said, if the vent valve is undersized, then it seems I'd be better off replacing it with a larger one that can dump the air out of the pipes quickly when the steam comes on.  Are there any other benefits to replacing the small vent valve with a larger one?

Dave_127

Replacing the Main Vent

Well, I didn't see any pipe dope or teflon tape on the reducer/nipple.  I'm reluctant to try to break it free for fear of breaking something else in the piping.



How bad is it if I leave the smaller vent valve in place?  It is a Dolen 1933, which seems to be equivalent to a Vent-Rite 33.

nicholas bonham-carter

small main vent

without a proper sized main vent, you are paying your fuel company extra money to force the air out; however this is probably a summertime project, as there is a slight possibility of rounding the flats on the bushing, and having to cut it out.

the lack of main venting, and over-pressure are the fuel companies friend.--nbc

Dave_127

Replacing the Main Vent

I appreciate the advice.  I'm guessing that I should hold the pipe with a pipe wrench instead of just trying to turn the bushing with a wrench and depending on the other pipe connections holding the pipe securely enough to turn against.  Right?



If I round off the flats, I'm not sure how I'd cut out the bushing.  The best I'd be able to do is to cut the top off of it, but the threads would still be embedded in the steam pipe.  How would I get the bushing out?



Also, would it make sense for me to spray some Liquid Wrench on the threads every week so that, by the summer, the threads might be loosened?

crash2009

Dave

Are you trying to flush this system through the air vent on the convector?