Steam boiler blowdown help

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I believe they are both electronic. I'd be a bit more worried if you had a mechanical low water cut off, there's usually a float in there that may stop working if there's too much sediment. Yours looks like it's just a sensor probe, look up the specs for that cycle guard. The VXT is the auto water feeder. You can easily just test to make sure that they're working, if the boiler is running, you just let enough water out til the low water cut off kicks in and the boiler stops firing. If there's no water in the sight glass and the boiler is still firing, then your low water cut off isn't working. Chances are it probably is working otherwise the boiler would be dead now. But yes, if the low water cut off or the water feeder fails, then it's usually the end of the boiler. Probably why they're only rated for 15-20 years instead of 30-40 years like regular hot water boilers.
 

JHZR2

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Originally Posted By: Wolf359
Actually steam is less efficient which is probably why the highest AFUE you'll find is around 82% or so whereas for hot water you'll find that they go to 95% or slightly higher. Anyway, I have lots of steam boilers and I'd blow those down all the time. The drain valve is pretty low there, normally mine are higher and I have a bucket to catch it all. I normally just blow it down when the boiler is cold, that way you don't end up adding cold water to a hot boiler. Worse would be if you drained out too much water and then added cold water to an empty boiler, I think you'd risk cracking it then. But on yours, the feed button is part of an automatic water feeder so when the low water cut off kicks in, it's supposed to add water to the boiler so in theory you shouldn't run out while draining it. I'd still do it cold though. You're also missing a tube from the relief valve, in theory if the pressure builds up, it will blow hot water out of that relieve value so you normally want a tube on there that goes to about 6 inches off the ground. Home Depot also sells new steam vents if the vinegar doesn't clean them out. Steam is tricky too, you have to make sure that the radiators are pitched right so that the radiator is at an angle so that the water can flow back down the pipe. If it's going the other way, water will pool at one end and when the steam hits it, you'll hear banging. Very common problem.
Interesting point. The lack of low temperatures (you do need to raise steam after all!) creates a situation where you can't condense well, though I'd guess you could modulate. But the biggest benefit of steam that yields net savings it seems, is the minimal thermal mass yet huge efficacy of latent heat games... The issue with a hydronic like mine is that while I'm 95+% efficient, I have to heat gallons upon gallons of water, which also heats the whole system up along the way. Steam systems really use the radiators well as condensers, while the pipes don't have a ton of losses due to fairly poor gas to solid heat transfer rates. So you get more, higher quality heat, closer to where you want it, and don't have as much mass heating up to begin with. Maybe I'm wrong on some points, but I grew up with steam heat, parents still have it. I'd actually prefer it myself...
 
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Basically a BTU is a BTU. From memory, I believe steam is at 240 degrees vs hot water which is at 160 to 180 degrees. So you have to spend a lot more energy to get the temperature up. That's why steam is outdated now, you just use it if you have a one pipe system and don't want to convert to a two pipe system. You don't really do new steam installs in new buildings, just replace old steam boilers. As a Realtor I see lots of new construction and typically they either put in hot water boilers or forced hot air, never seen a steam boiler in new construction.
 
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A BTU IS a BTU, but there's as many BTUs in water with a 100C temperature difference as there is in the steam that is produced, so yes, it take a lot of BTU to make steam...as menay as to take the water from melting to boiling. But you get them all back when it condenses. As JHZR2 states correctly, the heat loss from piping is basically similar, but instead of losing whole degrees in transport of hot water, you lose no degrees, just a small percentage of the seam as condensate. It's more efficient to transport.
 
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If you're talking boiler efficiency, steam is an old antiquated technology. Basically AFUE is the measurement of how efficient a system is. I've never seen a steam boiler at more than 82-83% whereas steam boilers can hit 95% or higher, might have seen one at 97 or 98 percent once. The rest of that energy just goes up the chimney out or out a vent pipe. Doesn't really matter what the losses are, they just cost more to operate because they're less efficient and no one in the right mind would put one in today for new construction. I would think that maybe even the local government might stop you from doing so. I wish I could get rid of my steam boilers, but converting to a two pipe system would probably cost around 5k a unit or more.
 
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