Hi, this is exactly the kind of information I was looking for. We recently moved into a house in New England with steam heat (I've always lived in forced hot air homes previously). During the inspection I was shown how to add water to the furnace up to 2/3-3/4 full in the sight glass. That was in April and by the time I actually had to do it I kind of forgot which valve to use. Eventually I turned both the top and bottom (relative to the sight glass) valves before I found the separate valve that feeds water to the furnace. I filled the water to about 2/3 full but now the sight glass is entirely full. I'm afraid of breaking the furnace so it's important I adjust the top and bottom sight glass valves correctly.

If I understand your post, the top and bottom valves should be turned all the way counter-clockwise to leave them open at all times? What about the full sight glass I now see? My understanding is that I could break the furnace if I flood it, which I assume I run the risk of since the sight glass is full?

Thank you in advance. I will search for your other posts, as mentioned, in the meantime.

 

Are you sure it's full and not empty?

If you suspect either, I wouldn't fire the boiler until you had it all sorted out.

I highly recommend the book that Furd suggested below... read the sample excerpt that is available on that page [edit: hmmmm... either they took the excerpt down from that page, or it wasn't that page I saw it on! ... ] and you will be hooked. I think it's the best purchase a new owner of a steam heat system could make.

 

I turned off the heat last night and drained water from the drain valve until the water level reduced to about half the sight glass. I let the heat run then during the night and heard some knocking, but I heard that previously and believe it to be because I need to let the built-up air out of individual radiators.

Also - I'm planning to purchase the book, but I need to take care of these issues in the meantime. Thanks!

 

1. I drained a full sight glass to about half last night and found that the resulting water in the sight glass was very dirty, as compared to the clear water before. Does that mean I need to full run water through the system instead of just reducing the water level? Interestingly, after the heat ran during the night I found in the morning that the water in the sight glass was again clear.

2. Through a mistake of my own I futzed with the sight glass valves earlier in the week instead of the water feeder valve. So I re-opened the top valve by turning left. However, turning the bottom valve left actually tighten is whereas turning right loosens. Very odd, I know, but the bottom valve is very close to the water heater so is it possible whoever installed it reversed the valve so that open is clockwise? That said, can I test which direction is open vs. closed somehow?

3. After reducing the sight glass water level to half last night I turned the heat back on. Interestingly, the water level bobbed while the heat was running. Then I noticed is returned to level (non-moving) when the heat was off. I didn't notice it before so I'm not sure if that's normal?

4. When "burning down" [editor: do you mean "blowing down" ? - NJT] the water in the boiler (dirty water in the sight glass), do I also open the water feeder valve in order to run water through the system? I ask because only opening the drain valve last night to reduce the water level seemed to stop about when the water was half way down the sight glass and was still dirty? So should I attached the hose to the drain valve, open the drain valve, and finally open the valve that feeds water to the boiler?

Thank you for responses! I look forward to learning more about this steam boiler I've never used until now.

 

Ummmm... no, not likely... your radiators have [air] vents on them that take care of this automatically. If it's knocking, there's something else wrong... not 'built up air'

Why not post pictures of your system? Maybe we'll see something that we can help with... set up a free account at Image hosting, free photo sharing & video sharing at Photobucket and upload the pics there, come back here and post a link to your album so we can view it.

 

Gryfon, I've moved the few posts from the other thread you were posting in to this one. Makes sense to keep your discussion separate...

I'm copying the link to the "We've Got Steam Heat!" book here for convenience:

Heating Help

 

This is one of the reasons why I dislike residential steam heat, a hot water system can almost be ignored and it will be fine but this is NOT TRUE of a steam system. Steam boilers need to be checked at least weekly and in most systems they need some "hands on" work every month or two.

ALL VALVES that have "handwheels" turn counter-clockwise to open when facing the valve handwheel. It is impossible to modify a valve to operate differently.

Gauge glass valves MUST ALWAYS BE OPEN except when changing the glass or blowing out the passages. Very few residential steam boilers will have a "real" valve on the gauge glass drain but will instead have a "petcock" (I hope that word gets past the auto-censor) that will make it all but impossible to open and close when the boiler is steaming. That is unfortunate because it is when the boiler is steaming and has (some) pressure that you really want to open the drain and blow through the upper and lower connections individually to ensure the passages are clear.

If the upper connection of the gauge glass is plugged the water level will rise to the top very rapidly on a steaming boiler because the water in the glass will condense the steam above the water level in the glass causing a partial vacuum and allowing the water to rise. If the lower connection is plugged the glass will slowly fill to the top because of the steam condensing in the glass and filling it up.

A steam boiler in operation is constantly condensing steam in the top of the glass and pushing water out of the bottom back into the boiler. This is why the water in the glass looks clear when the boiler has been steaming for a while. Ideally the gauge glass should be "blown down" periodically while the boiler is steaming but unless you have a real valve on the drain connection it simply cannot be done without making a real mess and a real chance of burning yourself. If you do have a real valve and drain piping then you want to open the drain, close the lower valve (to blow through the top valve) then open the lower valve and close the top valve (to blow through the bottom valve) then open the top valve and close the drain valve. This should be done monthly if you have good water conditions and more often if you have poor water.

You also need to blow down the low-water cutoff (LWCO) when blowing down the gauge glass. Blowing down the LWCO when the burner is firing should cause the burner to stop, if it doesn't you MUST get the LWCO serviced immediately. Having a non-working LWCO can lead to boiler destruction.

In the same vein a "bottom blow" is necessary on steam boilers but not as often as the LWCO unless you have really bad water and/or severe leaks in the system. Unlike hot water systems, steam systems lose a bit of water every time they cycle. In a "tight" system with no leaks and properly functioning air vents (not steam vents as they should not vent any steam) this water loss will be minimal and with fairly decent water you can probably get by with a bottom blow once or twice a season.

Because of the continual need for replacement water I strongly believe every steam boiler should have a water meter on the make-up water piping. Water meters are fairly inexpensive, usually $100 or less and they can help you to determine how often you need to do a bottom blow and also the LWCO blow down. Understand that an "automatic water feeder" is really for boiler protection and not a substitute for manually feeding water to the boiler. A tight system will usually lose more water from the periodic LWCO testing (and gauge glass blowdown) than it will in operation but a "leaky" system with leaking air vents, leaking valve packings or leaking piping will require more water and require it more often.

If you have "dirty" water in the boiler then you need to do a bottom blow. Do not blow so much water that the gauge glass is empty and do not blow when the burner is firing. If the boiler has been neglected it may take several blow downs to get the water clean. The water does NOT need to be crystal clear, a color similar to weak tea is just fine and any clearer is a symptom of excessive blow down but it should definitely not look like mud.

It is normal for the water level to "bounce" slightly when the boiler is steaming. A perfectly static water level when the boiler is steaming is an indication that the connections are plugged or very nearly plugged.

It could be that whoever installed either the boiler or the water heater banged the valve stem against the water heater and slightly bent the valve. I guarantee that turning the valve handwheel counter-clockwise when facing the handwheel is opening the valve.

 

I can recommend this company as a satisfied customer... good service, fast shipping, etc.

DLJ Bronze Water Meter from watermeters.com

 

So here are the photos I planned to post quite some time ago. I still have knocking in the radiators on occasion. Usually during the night - maybe when it's coldest outside? Maybe they're somehow working harder then?

I have a radiator that hasn't been working, though it randomly began to spew a small amount of steam/condensation a few days ago while the valve was "open". I found that strange.

You'll notice in the photos we have a steam valve on the units that (I assume) should help prevent air buildup in the radiators.

My biggest issues right now are the knocking and the unit that doesn't seem to want to work but spewed a little steam/condensation.

Thank you!

ImageShack Album - 8 images

 

How did you like the book? Learn a lot about your system from that?

 

It's on the way now - ordered it yesterday.

 

The knocking sounds are from water in the steam supply pipe. Steam under rising pressure eventually bubbles through or past water blocking the flow of steam, suddenly encountering enough cold water and steel to promptly condense. The pocket of steam that got past the water collapses quite suddenly shrinking in volume by a factor of something like 500:1. This creates a small pocket of very low pressure and in effect a low pressure pulse at that spot. That's the banging sound.

The root cause is almost always settling of the home's structure. The steam pipe would have been installed so that it was pitched to drain water back to the boiler. As the house settles the pipe hangers have to be adjusted to maintain that pitch. A solidly framed home whose floors don't flex when you walk across the room 50 years old or older might need to have the pipe hangers adjusted every 25 or 30 years. A less solidly framed structure might need adjustment every 5 or 10 years and may benefit from re-setting the nominal pitch for more reliable drainage.

NB: Steam systems are either designed as one-pipe systems where steam goes up the same pipe the condensate drains down, or as two pipe systems where the condensate is returned seperately from the steam delivery. I've seen two pipe layouts that had a looping style, so that you had to know where you were on the loop to figure out which way it should have been pitched. For both one pipe and two pipe systems the general answer is to pitch it away from the radiator, and toward the boiler.

Having gown up with steam heat, I don't think its as troublesome as all that, doesn't occupy every inch of every exterior wall with baseboard fin tube in an ugly litle tin shed, and supplies a radiant heat that you can warm yourself next to when you want that.

BTW- there should be "auto-vents" on the radiators, they should allow cold air to escape and close when hot steam hits them. There's an adjustement for how quickly they shut that can help balance the radiation. They should neither spit water nor leak steam. If they leak or spit, they're defective. They may only be jammed up on rust and you can try cleaning them out, white vinegar sometimes works. They eventually need replacing, just like the hi-vents on a pumped water system. You can also put in manual (aka key) vents to help purge air to speed the process, but they shouldn't be necessary.

 

Great stuff, thanks for the info.

As for the "auto-vents" - I do have those on my radiators and noticed the last couple days they have been doing quite a bit of hissing. It sounds like a little water mixed in with the hiss though no water is actually exiting the auto-vent. What's interesting is we virtually never had the hissing sound before we went on vacation. I set the thermostat to 55 degrees for 5 days with an outdoor temperature averaging somewhere in the low 20s. I figured the hiss was the system expelling the cold air that built up while we were gone but a few radiators still his when the system is running, even after 2 full days.

On a side note - our upstairs is suddenly much warmer than the downstairs using the same temperature settings we used before going on vacation. But that's probably a separate issue.