Where to drain a boiler. Drain valve vs LWCO

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  #1  
Old 06-03-16, 09:43 AM
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Where to drain a boiler. Drain valve vs LWCO

I have an old steam boiler that I'd like to drain. Over the winter I had to replace a number of new Varivalve vents that are continually getting clogged and it was suggested by my local plumbing supply store that there may be so much crud in my system that sediment is ruining my valves. The sight glass was so rusty that I could barely see in it so this morning this morning, I changed sight glass and decided to drain boiler.


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I figured draining was done through one of the two circled valves in photo but when I opened those, nothing really came out. I am able to open the yellow handle on bottom right and drain off LWCO (which I did twice a month throughout winter) but is that also emptying the boiler of water or just the LWCO?

I did drain LWCO down, refilled with clear water and ran the system to burn off oxygen and the water in the glass already looking murky.

So, my questions are - does draining with the yellow handle drain the boiler? Should water be emptying out of the circled valves? If so, how do do I fix that?

Lastly, it was advised in previous thread that my Varivalve problem might be due to pressure and that I should install a pressure gauge. I read the sticky that describes what I should be buying but where would I attach it? I don't see any valves on my system to accommodate a gauge.

Thanks
 
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Old 06-03-16, 09:59 AM
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Yes, both of those circled valves should allow water to drain. Draining through the low water cut-off is necessary but will not remove any sediment in the boiler proper.

You need to remove a bunch of piping and get that boiler thoroughly washed out. You CAN DIY or you can get a contractor to do it but if the latter you need someone that really knows steam systems.

I personally think that ALL steam boilers should have a make-up water meter so the amount of water added is easily tracked. You need to "blow out" an equivalent amount of water on a regular basis or the dissolved and suspended "dirt" in the water (mostly minerals) will not concentrate in the system. Unfortunately, few residential steam systems are piped to allow for such blow down.

As for the pressure gauge issue...There are several possible places to add a pressure gauge. Please post several more pictures of the installation for me to make a more specific suggestion.
 
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Old 06-03-16, 11:59 AM
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Thanks Furd. I'll likely end up calling someone to clean this out but if I did attempt to give this a go, which pipes would have to be removed? Could I just try snaking or replacing the two circled valves in photo? If so, would draining via the LWCO remove enough water from system allowing me to remove one of those valves without gallons of water pouring out? Apart from flooding my basement, I guess the other worry is trying to remove one of those valves and having something snap off.

Regarding installation of a gauge, I've attached a few more photos. As you can see, there is a gauge on there already, but it unfortunately doesn't work. Am I better off just trying to replace that one?

Thanks again.

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  #4  
Old 06-03-16, 12:32 PM
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Hint for next time you post photos. Do a double line feed (hit the enter key twice) between each picture so they don't run together.

I see some things that are very definitely screwy. Your wiring is definitely in need of some rework. That pressure gauge is improperly mounted and is the wrong one for a steam boiler. The safety valve appears to be for a hot water boiler and probably is not rated for steam operation and is probably too high of a pressure setting.

Yes, you can drain much of the water from the low water cut off drain. Removing the other drain valves and rodding out the piping may be enough to allow a decent flush of the boiler proper.

Be forewarned, if this boiler has been neglected for too long it is possible that the sludge, scale and other corruption is now sealing internal leaks. Cleaning it could reveal these potential leaks and this could require replacing the boiler. I couldn't see enough of the top of the boiler and piping to see how hard it is going to be to wash out the boiler from the top.
 
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Old 06-03-16, 01:03 PM
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Thanks. I had some luck and was able to clear the upper drain with a small pike snake and that is now flowing fully. How much of the water should I drain? At this point, I just drained until water ran clear and then refilled and am running system again. Should I instead drain until it's empty?

Once I've drained it properly, is that all there is to cleaning it or is there more work to be done? You mentioned cleaning it from top but I"m not sure what that means.

I hear you on the warning about sludge possibly covering leaks. I thought about that as well and wonder if I should be attempting to clean this at all. I've only lived in this house for less than two years but was told by service man that boiler looks like it's been properly maintained. That said, he didn't say anything about pressure relief valve or gauge being wrong so now wondering how good he was..

Have attached a few more photos of top.

Thanks.


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  #6  
Old 06-03-16, 01:37 PM
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Ideally you want to wash out all the mud and foreign material inside the boiler. You might be able to do this with a variety of small probes made from copper tubing that will allow you to connect to a water hose and then insert the tube through some of the ports on the side of the boiler. The low water cut-off should have the switch assembly removed and washed out. The gauge glass valves should be removed and the passages to the boiler washed out.

Step back as far as possible and take some pictures of the boiler AND piping. I need to see how the entire system is put together.
 
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Old 06-03-16, 02:09 PM
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Hi Furd,

More photos attached. I don't really see any ports where I might be able to put a garden hose in but I'm assuming you mean it would be with the garden hose turned on in order to move everything around?

I could probably handle cleaning out LWCO. I just changed sight glass so remove that again and wash that out. I was told by service guy that my auto water feeder has been turned off so I'm assuming that doesn't work.

Thanks


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Old 06-03-16, 02:17 PM
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I hope that R.Beck, our resident expert on residential steam systems sees this thread and comments. My experience is with commercial and industrial steam systems.

What I meant about the probe was that you could make up some adapters to allow connecting a small tube such as 1/4 inch copper, to the garden hose and then insert the tube through the drain valve connection as well as the gauge glass connections. With larger boilers we use crosses with plugs rather than tees and elbows so the plugs can be removed for cleaning purposes.
 
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Old 06-03-16, 02:26 PM
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I see what you're saying. Those drain valves look like they've been on there awhile and I'd be nervous about trying to remove and potentially cracking something important. Perhaps R. Beck will chime in but otherwise, I'll probably flush it a few more times and hope for the best at this point.

Last question though, regarding a pressure gauge, do you see another place I could put one on or am I better off removing old one and installing one there?

Thanks again for all your help. I appreciate it.
 
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Old 06-03-16, 02:55 PM
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Off the top of the low water cut-off there is a coil of pipe, called a "pigtail" or siphon, that traps water in the coil to prevent hot steam from reaching the internal parts of either the pressure switch or a gauge. Commonly there is a tee installed between the siphon and the pressure switch (often called a pressuretrol although that is a registered trademark of Honeywell corp.) where the pressure gauge is installed in the third branch of the tee.

You want a pressure gauge that reads to a maximum of 15 psi and although much harder to find, a maximum of 5 psi is preferred. Residential steam boilers operate best at less than 1/2 psi so that existing gauge would probably never have moved off of the zero point, or at least not enough to notice. Also, located where it is the internals are probably damaged from the admittance of hot steam. You could remove that gauge and install a second siphon (pigtail) and then a new gauge in its place.

Also, look closely at the safety valve to see what its rated pressure setting is, it should be 15 psi and it should state steam on it. If it is 30 psi or does not have the word steam, it needs to be replaced.
 
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Old 06-03-16, 03:22 PM
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Thanks. Will pick up a proper gauge and T connector. The steam valve has a tag on it and seems to be this one so think I'm good.

The valve is a Watts #315 Steam Safety Relief Valve with a 15psi so think I'm good there.

Thanks again.
 
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