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Leaky sight glass on a steam boiler (C) Daniel Friedman Steam Boiler Sight Glass Repair FAQs
Q&A on fixing a steam boiler sight glass

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    • Steam boiler sight glass repair or replacement FAQs:

    Questions & answers on how to replace a leaky or broken sight glass on a steam heating boiler.

    This article series describes how to fix a leaky or broken steam boiler sight glass to obtain an accurate reading of the water level in the boiler.

    We discuss emergency steps such as simply shutting off water into and out of a leaky sight glass as well as sight glass replacement.

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    Steam Boiler Sight Glass Repair / Replacement FAQs

    Steam boiler sight glass showing required water level (C) Daniel Friedman

    These questions & answers about how to replace a broken or leaky steam boiler sight glass were posted originally at SIGHT GLASS REPLACEMENT - be sure to check out the advice given there.

    On 2019-06-19 by (mod) - give me your best price on steam boiler sight glass

    Sorry MD,

    But we don't sell anything. In order to protect your reader trust and confidence and what they find here this website sells no products nor services at all.

    On 2019-06-19 by Md saiful islam

    Sight gass glass price bd
    full set up

    On 2019-04-09 by Mary

    I apologize, I wasn't trying to be facetious about the time of reply. I was just curious. I appreciate your help VERY MUCH!! I will try what you said and try with caution. Again, I apologize and THANK YOU!!!!

    On 2019-04-09 by (mod) -

    Mary

    Forgive the 19 minute delay in answering your questions. Yes we try to answer every reader question, but with millions of readers, sometimes we can get a bit behind.

    Most heating boilers have a BOILER DRAIN VALVE located usually near the bottom of the boiler. It looks like an outside spigot or faucet.

    But

    WATCH OUT: the drain valve, having never been touched for some time, may be stuck, corroded, or may leak and be impossible to close again completely when you open it.

    What I do as insurance is to have on hand a simple garden hose cap that I can, if necessary, screw over the drain opening to stop leaking until my plumber or heating contractor can repair or replace the leaky valve.

    Watch out: also not to try draining a hot boiler - you can get burned. Let it cool down to room temperature first.

    On 2019-04-09 18:16 by Mary

    Does anyone ever answer these questions?

    On 2019-04-09 18:13 by Mary

    I have a utica boiler that you add the water manually. Because the sight glass was a little dirty, I added more water than I should have. How can I reduce the water level to the normal level? Whatever part you tell me to use, please tell me where it is located. Thank you.

    On 2018-12-18 by Josh

    When the sight glass gets completely clogged with dark brown crud that's imobile, does this pose a danger to the furnace system assuming all other features are working?After turning the furnace off, obviously the furnace needs to be drained till the water runs clear and "Steam Clean" or another cleaning chemical needs to be added each year. But does the clogged sight glass pose a hazard until it can be cleaned or changed?

    On 2018-12-18 by Josh

    When I had my old oil furnace replace twelve years ago, I replaced it with a gas -hot-water furnace. The contractor did not tell me that it would get clogged with rust from the returning steam until it happened and I called him. He claimed I could / should replace all of the pipes returning the steam to the furnace

    . I did not plan on staying or keeping the home that long and he had already soaked me (it appears underhandedly w/ supposed chimney work which another contractor said was fine and not in need of work etc.) for enough money so I declined.. It has an automatic water fill but he said it should be a certain level so I did the manual feed lever fill thing but it continued to fill after I shut the lever off.

    The site glass was overfilled so I called him. He seemed to 'panic' and said it had to be drained and he had to run a chemical through it and charged me $275 back in 2007. He continued to say it had to be done each year or so. This was only a year or 2 after he installed the new furnace. At some point I called in a plumber who was rec. to me by a professional friend of mine. He looked and said: "this furnace was never inspected by the city"! The new plumber charged me $10 and showed me how to put bottle chemical called "Steam Clean " in it! (Maybe you can recommend a better one) I realized the original contractor who acted like a nice guy and a friend was a freaking thief and con artist and had ripped me off all along from the beginning!

    Now my sight glass is filled with dark brown crud. How do I actually remove it. I read your article on shutting the furnace off, letting the water cool and then remove it but it seems anchored on the top and bottom of the actual sight glass with a brass nut on the top and bottom of said sight glass and I cannot remove it with a wrench when I attempt to I had to stop for fear of breaking the glass.

    Should I do it or have PSE & G come in and do it since I have a service contract with them. After reading your article it seems like I should simply buy a new sight glass. Also how do I clean the automatic water feeder or can PSE&G do that.

    Also how often should it be done. The installer/contractor never gave the the manufacturer's booklet that all products should have! What a piece of garbage he was/is!

    On 2018-10-26 by (mod) -

    That sounds to me as if the upper valve on the sight glass assembly is closed or blocked off with crud and sediment.

    On 2018-10-26 by Andrew Brooklyn NY

    I have a problem with sight glass level. A boiler is equipped with manual water adding. When I add water to the boiler manually in the sight glass water rising to some level and stops despite the fact I've not stopped the water. If I do not stop adding water it will flood the boiler

    . When I unscrew the valve cartridge from the upper valve on sight glass, water in the glass raising and water speel from that valve. Manually I drain the water to the correct level, then install back vale cartridge.

    As soon as I install back cartridge, the water in the glass raising up and fill up the glass. When I remove the cartridge, water level lowering to correct level. Both valves on the glass I cleaned and water from boiler have a clean connection with glass tubing. Can you describe the problem, please?

    On 2018-10-08 by John Szostek

    sightglass gets brown then cant see level . how do you stop the brown water in the boiler.

    On 2018-03-21 by (mod) -

    J

    it's not so likely that an o ring itself would damage the sight glass on a steam boiler.

    More likely would be someone over tightening a metal fitting and breaking the sight glass.

    So I suppose if you had the wrong sized o ring and it were leaking, someone might try to fix the leak by over tightening the fitting in that would then break the sight glass.

    On 2018-03-21 by July

    how o ring damage boiler sight glass

    On 2017-06-19 by Will

    Is it ok to tighten the nut of a leaking site glass if its hot?

    On 2017-03-19 by (mod) -

    ... replaced.

    On 2017-03-19 by (mod) -

    Thanks for the great question. Provided there are shut-off valves at the upper and lower sight glass connections, it should be possible to have closed those valves, removed the old perhaps broken sight Glass, install the new one in the same fittings, and then open the valves again. A little bit of air in the cyclists will not be relevant to the operation of the system.

    However if the new sight glass leaks then we need to look carefully at the rubber or other seals in the sight glass mounting fittings, because those may need to be cleaned or

    On 2017-03-19 by Oscar

    What is the right procedure to put the sightglass on line again?

    On 2016-11-06 by mod) - can I close off the sight glass valves if the glass is leaking?

    Yes, Ken. But you won't know the water level in the boiler.

    It's fine to close the sight glass valves to stop a leak but you should go ahead and have the glass replaced.

    On 2016-10-11 by KEN DAVIDSON

    Can I shut off the valves at the top and bottom of the sight glass and still run the system? The sight glass is leaking from the bottom.

    On 2016-02-24 by mod) - should the steam boiler sight glass valves be normally open or closed?

    Good question, thanks for asking.

    The sight glass valves at its top and bottom are normally both open. That allows the glass to show boiler water level.

    If the glass / sight gauge is leaking or broken you'd close both valves to stop the leak and to permit replacement of the glass.

    On 2016-02-24 by Joan

    Should the shut off valves at the top and bottom be open or closed ?

    On 2015-12-18 by mod) - do you need both upper and lower valves on the sight glass?

    If I understand your question it's about shutoff valves at the top and bottom of a steam boiler sight glass.

    These valves are important to permit the boiler to remain in operation should the glass itself become broken. In a safe residential location where breakage is not much worry or if there are other shutoff valves between the sight glass and boiler, you might be fine with a kit that didn't include both of them.

    The valves also permit change-out or replacement of a broken sight glass without having to drain down the boiler.

    On 2015-12-18 by Tisha

    Some of the water guage kits come with fittings (maybe a check valve) instead of the handled valves. Some of the kits only come with one valve at the bottom. When do you need to use two valves vs. one, etc.?

    Question: water is rising in boiler sight glass but I'm not adding any

    sight glass on steam heat furnace with indirect heater water rising without adding it I have a manuel feed I took off union checked
    manuel feed not leaking any ideas indirect heater 4 yrs old - Harold Nobile 3/3/12

    Reply:

    Harold, if your system does NOT have an automatic water feeder and you see water level apparently rising in the boiler anyway some explanations could be:

    Question: boiler sight glass problems?

    I had a fill sight glass replaced by a service technician because it crack. Before that repair, my boiler was automatically feeding water. After the repair, it seems that I manually have to open the valve. There are three valves that are close together and seem to be connected to the same pipe.

    Now I have to turn my boiler on much higher than before to get it warm in the house. - Anon 10/23/12

    steam boiler's sight glass is rusty and every time the boiler comes on the automatic water feeder,feeds water to the boiler filling the sight glass above the required level

    i have been reading the other problems on this site ..is there a required height for the auto feeder to be installed in relation to the sought glass ? - Phil J 11/2/12

    Reply:

    Anon: you want to call your heating service tech to have him/her show you the water feed valve setup and to check the condition of the automatic water feeder. Perhaps the sight glass repair stirred debris that has entered a valve or control. Try flushing things out.

    Phil,

    There should be a tag, mark or line on the steam boiler face behind or next to the sight glass giving the proper fill level. Filling above the glass would be unusual. Perhaps your automatic water feeder meds cleaning, service, or replacement.

    These heating boiler leak diagnostic articles may also help troubleshoot steam boiler sight glass crud or leaks:


    ...

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