Experts All,
I have a two story, 3-unit apartment building that is about 80 years old. Still has the original cast iron boiler – hot water system with cast iron radiators, natural gas fired..
In 10 years of ownership, I’ve always had to tweak the system a bit now and then (add water) as the pressure would drop anywhere from 2 – 5 psi from the initial setting. At the end of the 2008 heating season, the pressure dropped to zero.
The relief was in bad shape, corroded, so I replaced it. I then filled the system during the summer and looked into the boiler to see if the heat exchanger was leaking. No leaks. As a precaution, I changed out the bleeder valve on each radiator, and repacked all the stems of the radiator valves.
I started the heating season this year with the pressure holding at about 18lbs. Held that way for a couple weeks, than needed a fill. OK for maybe three weeks, than another fill. No rhyme or reason to this, except that the pressure slips anywhere from 2 to 6lbs (read when the boiler is on standby).
This system does not have a circulating pump. Since there are two massive cast iron manifolds where all the delivery and return lines meet (encased in asbestos, at that), the only place that I could install a pump is away from the boiler on a secondary delivery or return line.
My idea is to install a circulating pump for the simple purpose to circulate boiler stop-leak that I would introduce into the system. I’d rather not replace the boiler at this point.
Would a circulating pump away from the boiler itself eventually circulate all the water that is in the system so that the stop-leak is eventually circulated throughout the entire system as well, or is this a far fetched idea?
Any advice would be appreciated. Thanks for your time.
DIA
Replies
Greetings doitall,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
Let's run this thru one more time.
bump
For 15 years, I lived in an apartment building in NYC with an old boiler like that but I don't know much about them. Only thing I can tell you is that every time the system went down, the plumbers found (and replaced) a leaking tube in the boiler itself.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Thanks for the input, but this is a small boiler with no replaceable tubes. My main question is: will every "unit" of water eventually circulate through the pump if it is not installed directly on the main feed (or return) at the boiler (but rather on a branch line)? Have I actually stymied all the plumbing and heating experts here?!!Have a good day.DIA
No sense using chemical until you are sure there is a leak. Sounds like you have a gravity system. Expansion tank should be at the top of the system. Assuming it is, check the level in the tank and then the pressure at the boiler. Then when the pressure drops, check the level in the tank again.
Water is about 7% dissolved oxygen. As the O2 comes out of solution when heated and is released to atmosphere, the volume of the system will drop. As the volume drops, so will the pressure.
And your pressure gauge could be bad. Every 1psi is equal to about 2.3 feet of water above the gauge.
Edited 3/8/2009 4:33 pm ET by rich1
I suspect that you have a leak in the boiler and the missing water is going up your flue.
Go to this site and post your problem. There are hot water heat experts may help solve your problem.
http://forums.invision.net/index.cfm?CFApp=2
Thanks for the input. I will post there and see what happens. By the way, the expansion tank is hanging from the ceiling joists adjacent to, and above the boiler. That's the way that I've always seen them installed around here (MN).Thanks again,DIA