trying to understand steam heating

steam2801

I have a 20 year old, single return, steam boiler for a three story house in Ohio. In severe cold I need to feed it water every day. I was never concerned until this very cold winter. It seems it uses more water as the temperature outside gets colder. There are some contradictions in the information I have learned. I watched Dan Holohan's excellent video, read his books, and watched an episode of understanding steam heat on education t.v. In Dan's book he states "A one pipe system will often add humidity to your home whether you want it or not". The WVIZ tv guy "This Old House" says you should not have to add water to a boiler, that the water that was put in it years ago can still make the steam because the steam reverts back to water and so on. Now if you are adding humidity to your home you must be getting the water from some place which is the steam heatiing system, so you will need to replace the water. The more I learn the more confusing it gets…..

mattmia2

@DanHolohan 's "A one pipe system will often add humidity to your home whether you want it or not" is a joke. He is saying it will add appreciable humidity if it is leaking somewhere. If it is working properly it should only lose a small amount of water, like a gallon to a couple gallons a month, not enough that you have to feed it every day or even every week. If you have to add water more than once a month you have some sort of leak somewhere.

The water should be boiled in to steam in the boiler, be condensed back in to water in the radiators(and a little bit in the piping) and that liquid water should return to the boiler through whatever return system that particular system has, either dedicated returns or through the main to a return at the boiler or some combination of the 2.

It is essentially a closed system except it fills with air when it is off and that air is vented out when the system is running to make space for the steam. A little bit of water evaporates in to that air that is vented out, that is why you lose a little bit of water.

If you are adding water every day either you have large steam leaks and will likely have condensation on walls and windows and such, it is leaking out of a buried return where you can't see it, it is leaking out of a hole in the boiler and up the vent, or it is coming out of a vent or a relief valve as liquid water.

Note that on one pipe steam a partially closed radiator valve will frequently cause the radiator to fill up with water, valves must be all the way open or closed on one pipe steam.

dabrakeman

Theoretically you should lose very little water other than that from evaporation and a tiny bit of steam lost as a vent closes. I'm sure there are varied views on what is normal but I would think a gallon a week shouldn't be exceeded. You should check for leaks anyway. If you are seeing more water loss due to cold temperatures it is indicative of being something above ground and not a buried return (don't know if you have any or not) which is good. The cold weather is likely making your radiators completely fill more often than during shoulder seasons or warmer winter days. If there is a faulty radiator vent only then is it revealed causing steam/water loss. Have you gone around and checked your vents with a mirror or light when the last section of the radiator is steam hot and the boiler is still running? If some steam is escaping there is your problem. Check radiator valves and make sure you are running low <2psi max pressures. Break up any recoveries if you are doing them.

CoachBoilermaker

I know nothing, but low water can mean leaking boiler?

Or cracked boiler with steam going up chimney? Do you see white steam exiting chimney?

Mad Dog_2

My best advice? Purchase "We got steam heat..." by the founder & Moderator Emeritus Dan Holohan. It's a quick & witty read that will 'splain what you need to know as a Homeowner. Mad Dog