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Large leak from backflow preventer on gas water heating system
I have a gas fired baseboard hot water 2 zone system. Moved into this home a year ago had no issues during the heating season. Today I was installing floors in one of the bedrooms and may have nudged the baseboard pipes once or twice, but nothing hard, just tap here and there -- same as kids would do playing around ... At the same time I did have water turned off at the main since I have a well water filtration system in that bedroom closet and did not want to have issues with water as i moved some of the items around during the floor work. When I finished the floors, i turned the water back on and in my utility closet I heard water hitting the floor -- I peaked in and water was pouring out of the backflow preventer valve, which is located at the feed to the boiler. There is a water feed off valve ahead of the backflow preventer, which i turned off and it made the leak stop. The system is appx 30 years old and I am not sure whether anything has or has not been replaced during that time. What could have caused the sudden leak and what options do I have to stop it?
many thanks for your help!
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Comments
What is your incoming water pressure? Do you have a thermal expansion tank on the water heater?
Filtration equipment often have check valves so you may need to have a DHW expansion tank added.
If you heating system holds pressure, no leaks, many installers prefer to leave the fill valves turned off. I'd be sure the boiler has a working low water cutoff safety, properly installed.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Best thing at that age is to replace it, particularly if it is really dripping -- never mind running -- and not just "spitting" a little.
On expansion tanks. This is well water? You have, of course, and expansion tank to control the well pump. At least I hope you do -- otherwise the pump is destined for a short and miserable life. You also have an expansion tank on the hot water heating system. Now. If there are any other check valves in the domestic water system between the water heater and the well pump control tank, you must have another expansion tank to account for the hot water expansion.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
My biggest challenge is with how tight it is where the backflow preventer valve sits -- it is positioned in a small utility closet BEHIND the boiler in the very corner -- there is not enough room for even a bucket under it -- probably 2 inch of room around it as it is against a wall and pours water onto the wall ... not optimal setup, but since this is all in a small closet when they built the house they did what they could to fit it all in... When i was installning a new hot water heater, i had to dent the side of it to make it fit because of how tight it is in there ..
Any ideas on how to 'encourage' the valve to seal correctly? maybe some pressurized air into the vent side? I'm trying to think what I can do without disassembling half the boiler to get to that valve ...
What make and model backflow preventer is this? It is remotely possible that you might be able to get the offending part of the valve to clear and seat properly if you could flow a large flow through the valve. Without seeing how your boiler piping is set up I'm not just sure how you could do that without really messing up your hot water heating system though.
I would presume all this is on copper pipe? You may find that the easiest thing to do -- assuming that you have other useful valves (which you may or may not have...) is to remove the backflow preventer entirely from where it is, and relocate a new one where you can get at it. I'd have to look at the space, though, to see if that would work -- or is even feasible.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Got a pic? Most are easily disassembled to service or clean out.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Yes this is on a copper line -- replacing it with one higher up may be better, but a difficult job without taking apart much of the boiler's exhaust and expansion tank..
Here is a couple of photos to show how difficult to access and what valve it is.
On label it states BFP-90 by MDRCA Corp.
Here is a cutaway of what is inside, the black lines are all sealing areas, one on each check and the spool in the center.
Installation and testing procedure, although you know it leaks
Some times you can disassemble and clean some crud out. The longer it leaks the more prone to seat damage which is not rebuildable.
Ideally the should be mounted in a horizontal line.
It has union connections, changeout should be fairly easy once you get to it.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Like the expansion tank, that double check is old. I'd replace both. See: Supplyhouse.com
http://heatinghelp.com/blog/how-diaphragm-tanks-came-to-be/
Then again, some of the older versions of hydronic components will last longer than todays "value engineered" versions.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
If you have the room, move the BFP to a more easily serviceable place.
You probably have debris caught in the check valve portion of the BFP triggering the the darn thing to discharge.
That BFP is very serviceable if you can get to it. It comes apart relatively easy when in a serviceable place. So, if you can get at it, take it apart and clean it. After that it should seat nicely.
Considering its age and its current location however. I would replace it as mentioned above.
The debris more than likely got caught in the BFP because you turned the water main on to quickly?? Drawing water and rust from the other side of the main. Next time go very slow when opening the main valve.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Disconnect the fill and add a low water cutoff is an option. Probably a good portion of old fill valves are seized and would not work if they had to
BFDs like thermostatic mixers are valves that need occasional service to assure they are working correctly.
Keep pressure spikes and droops away from them so they don't have to "move" will keep them healthy longer.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Inspectors is some areas consider them adequate protection for a boiler filled with plain tap water.
Start adding chemicals and glycols to the boiler water and you want a higher protection level.
If you are on a private well system, by yourself, the check is there to protect your potable water.
On a public water system the BFD protects everybody on the system and more and more cities are asking for RPZ , testable type that require documented yearly inspection and re-certifiction $$$.
If you replace it with a like product spend the time to run the vent to a location where discharge can be handled, a floor drain with and air gap ideally.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
related question - in it's current state was there any potential the valve would be letting water out of my boiler and into my pottable water? for example if i turned off the water, so there is no pressure and then opened the taps with the feeder in the open position and the valve in its current partially open state?
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
The labels on most are riveted on, and the holes are drilled thru to further prevent the center chamber from being pressurized, although not much of a flow path around the rivets, they will seep or spray to indicate a failure.
There are probably a dozen different types of back flow devices built and certified for various applications, the level of hazard and application determine which is best, as well as the local code enforcers.
I think you have a good plan, although I would add a LWC if you valve off the fill, for additional piece of mind, and code compliance. Most of the modern mod con boilers have pressure switched that lock out ignition if the boiler pressure drops indicating a possible low or no water condition. Flow switches are used on some applications, but a probe type LWC is really the best protection.
Yet another safety device to keep serviced and operating properly
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me