Radiator Heat

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Jun 6, 2013
Quick question: My son and a buddy are moving into a rental house this weekend and he did a walk-thru this evening Landlady is a recent widow and not 100% familiar with everything... she was explaining to my son about the heat and a glass water tube that indicates whether or not water needs to added ...? I may be way off base on this and I wasn’t there, but doesn’t anyone have any familiarity with radiator heat and what this glass tube is all about? Thank you
That would be a steam boiler. It is probably very old since they are seldom installed any more. The tube is a sight glass that shows the level of water in the boiler. Usually there is an automatic control to add water, and another control that will shut down the burner if the water level is too low. It should need water only very occasionally unless there is a leak.
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That sounds like a steam boiler which has a sight glass for water. I still have several of those. The newer ones have automatic water feeders like the Hydrolevel VXT. You can retrofit them to older boilers but it typically requires an electronic low water cutoff and some of those older boilers just have an older Mcdonnell Miller 67 which won't work with the newer water feeders. Probably costs a minimum of $500-$1000 to retrofit an old boiler. Anyway, yes, you fill the water up close to the top of the sight glass. Don't go over because the pipes will bang if there's too much water and you're paying to heat that water. The low water cut off shuts off the water once it gets too low so then you'll have no heat. Normally you want to add water slowly so you don't crack the boiler by adding cold water to a hot boiler. Steam shouldn't be coming out of the steam vents, if they do, you need to get them replaced as that will cause you to have to add water more frequently. Normally you have to add water every 2-3 weeks.
Also with any gas or oil heating system make sure to keep a working CO detector in the house.
Thanks all,,, I’ve always heard that’s the best heat there is but never saw the guts of one before. Ran over there and it’s a nice place... site glas is right there in plain view but dirty. Flushed out some water and refilled but still dirty and I didn t want to mess with it. Heats the place up well. I imagine once we get a cold snap where the boiler will be running for a stretch, that will be one very toasty basement Again, thanks for the input
Steam is an old system. AFUE isn't really that high, maybe about 82%. A hot water direct vent boiler can go up to 96% efficient. Basically steam boilers have to heat water up to 240 degrees to get steam, hot water is more in the 160-180 range so you spend less energy heating up water. They can also bang if the radiators aren't pitched right. Single pipe systems mean that you can't easily convert it to hot water. Some like them because you get some humidity with it from the steam, but the steam vents are supposed to close when the steam hits and just let out air. Anyway, for the boiler, there's a blow down valve on the Mcdonnell millers low water cutoff, you let out the dirty water every time you add water. You want to do that on a regular basis otherwise if the low water cut off gets filled up with silt, the float will stop working and your boiler will basically overheat and crack the boiler. One of the dangers of a steam boiler, they don't last as long as hot water boilers. You can actually disassemble the hardware around the sight glass and clean the glass inside. Blowing it down won't clean it once it's dirty like that.
Very informative Wolf...! Thank you. I’ll take a look at some point this weekend Thanks again
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