Flush the wet return

SteveJones

Hello All,
My home is heated via a 1 pipe steam system. The wet return line was replaced roughly 15 years ago. This line runs the length of my home, about 6-7 feet of it is buried below the concrete floor.

It has not been cleaned / flushed out since it was replaced, and I am thinking it is overdue. One heating guy I had to my house said “don’t worry about it” and did not pay much attention to my concern, and he did no maintenance on it. I do not want to have to replace this again, so i still think it should be flushed! I like to think I am pretty handy, I do my own burner tune ups, etc, but I’m not sure how to approach this. I’ve read on this site that a good way to flush is to have a ball valve in the line right before the Hartford loop (see green arrow in picture), and another valve just prior to that (see red valve in picture). Force the boiler to run until you get a couple of PSI in the system. At that point close the ball valve, and open the valve just prior to it (connect a hose to it to route out the water & crud that will rush out). The pressure in the system would force any water & crap out of the wet return line.

That all makes sense to me and I would try it, trouble is I don’t have the ball valve in my line. (again see attached picture of my specific system). A “Pro” installed this wet return. Does that hopefully mean there are other ways to flush this wet return that I am unfamiliar with? Or do I need to install a ball value and follow the above procedure? I appreciate any guidance from those more knowledgeable.

Also, would you think it is overdue to the point that I might have trouble with it soon?

Thanks in advance!

SteveJones

Picture:

Fred

The intent of a valve at or on the Hartford loop is actually to be able to close it off to prevent pushing any crud into the boiler. You get nothing from firing the boiler up and then closing a valve near the Hartford loop, in terms of pressure blowing out the wet returns. I see you have drain valves on those two wet returns near the boiler. Are there other drain valves at the far end of the wet returns? If so, what you want to do is open the drain valve at one end of the wet return and attach a hose to the other end and feed fresh water into it allowing the gunk to flow out of the opposite end. It's a good idea to flush out wet returns every year or two, if you have a convenient way of doing so.

Ironman

A tech with a ProPress could put a ball valve in there in a matter of a few minutes. That's the best way to flush it.

KC_Jones

Is the entire wet return copper?

JUGHNE

Was that 6-7' under the floor replaced? We assume it was.

You sound handy with tools. IIWM, First drain out the wet return using that hose bib as much as possible. Then I would saw the pipe riser going up to the upper Hartford upper 90 ell just above the lower black iron 90. Remove the vertical pipe riser.
Then unscrew the lower 90 from the copper wet return, put a tee there to replace the 90, add a reducer at the floor for a 3/4" ball valve with a hose adaptor.
Then replace the vertical riser with a nipple, ball valve, nipple, union and long nipple up to the Hartford Loop 90.
Now you have a good 3/4" drain at the floor and can keep sludge out of the boiler if you flush the wet return.
At the far end of the wet return if you can add a hose port then with a double hose connector apply fresh water to that point.

The caution is to not put in more water with the hose pressure than the new ball valve at the boiler can discharge. Otherwise you would be backing water up into the steam main . You would not want to hit your end of main vents with house pressure.

SteveJones

Fred said:

The intent of a valve at or on the Hartford loop is actually to be able to close it off to prevent pushing any crud into the boiler. You get nothing from firing the boiler up and then closing a valve near the Hartford loop, in terms of pressure blowing out the wet returns.

I politely disagree. If some pressure was built in the system, then the ball-valve (that I dont have) was closed while pressure was still in the system, then the valve that I already have was opened while steam pressure was still in the system, the steam pressure would force water / crud out of the wet return. The purpose of the ball valve being there and being closed would be to prevent (as you said) any crap going into the boiler. This is a way to force out stuff from the return without having to connect another fitting on the opposite end of the return to connect a hose to. It may be limited in how effective it is compared to forcing a consistent flush with a hose, but I think it would work. (At least from what I have read on this site as well as how I can picture it working in my head.) The wet return is basically connected to the open steam pipes. When they have pressure, if you open the pipe up somewhere its gong to want to push out until the pressure is relieved.

I was hoping to find out from this post if there are other recommendations on how to do this given my current setup.

Fred said:

I see you have drain valves on those two wet returns near the boiler. Are there other drain valves at the far end of the wet returns? If so, what you want to do is open the drain valve at one end of the wet return and attach a hose to the other end and feed fresh water into it allowing the gunk to flow out of the opposite end. It's a good idea to flush out wet returns every year or two, if you have a convenient way of doing so.

No, those are not wet returns. The main floor and second floor are heating via the 1 pipe steam. The basement is heated via hot water & baseboard, which is tapped into the steam boiler. The other drain valves you see are part of the one hot water loop that heats the basement.

Thanks for chiming in and trying to help.

SteveJones

KC_Jones said:

Is the entire wet return copper?

Yes the entire wet return (running the length of my house) is copper. When it gets to the other end of the house the copper continues straight up about 4 feet. There I believe it merges into old black pipe.

Do you ask because copper is easier to add fittings to, etc...?

Thanks for chiming in

KC_Jones

I ask because copper wet returns typically stay much cleaner.

SteveJones

JUGHNE said:

Was that 6-7' under the floor replaced? We assume it was.

Yes it was. And the copper that is buried is wrapped in some white insulator stuff, almost looks like soft PVC that it is wrapped in there.

Thanks for the other thoughts on how to plumb some fittings into a place I had not thought of. I was previously thinking to cut the copper pipe. I'll have to study your feedback more when I have time and think it through.

JUGHNE said:

You would not want to hit your end of main vents with house pressure.

Just so I know, why not? I had thought of this happening, but figured if it did happen, after a few minutes it would just drain back down the wet return. I figured all that stuff sees regular condensate when operating anyway.

Thanks Again

SteveJones

Ironman said:

A tech with a ProPress could put a ball valve in there in a matter of a few minutes. That's the best way to flush it.

Thanks. I didn't know what that tool was until now. I just researched it, very cool.

JUGHNE

The process I described would not require cutting into the copper. Also no pipe threading as nipples are available to fit between your union and ball valve, maybe a coupling depending upon what lengths are available.

Back flushing up into the main could push debris into your main vents causing them to not seal tightly. Same for rad vents if you really get carried away. All venting devices have a max pressure rating to prevent damage to the floats inside.
Actually you could remove your main vents and depending upon your main piping arrangement, you could very carefully inject water thru the vent tapping......matching the water going in to the water going out. This necessitates the need for a large straight ball valve lower drain.

I would guess most of your crud has passed to the lowest point of the wet return right at the boiler. Just like a trap under a sink collecting junk.

You may have read here of a boiler blow down where you isolate the boiler with valves, build pressure into the pounds range, inside the boiler only, and then open a lower boiler drain to blow down the lower area of the boiler.

Fred

@SteveJones , The purpose of an isolation valve on the Hartford loop, provided you also have King valves on the mains is so that you can build pressure in the boiler to blow crud out of the boiler. You won't build any significant pressure in the wet returns, unless you over pressurize the entire system which is not something you want to do . Most steam boilers should be running on a pound or less of pressure. Just closing a valve that you might put on the Hartford loop will only prevent condensate from returning to the boiler. It will stack water up in your returns but that isn't going to be sufficient to effectively flush the wet returns.
I also beg to differ with you. That pipe with the blue handle/drain on it is on the wet return, just before it goes up to the Hartford loop.

SteveJones

Fred said:

You won't build any significant pressure in the wet returns, unless you over pressurize the entire system which is not something you want to do . Most steam boilers should be running on a pound or less of pressure.

Most of the time my system does run a pound or less, except on maybe some of the coldest days or the year, and somebody jacks of the themostsat. My pressuretrol won't likely kick in until about 4 lbs builds up. Not perfect, but that can happen a couple times a year on my system.

So since it does happen anyway a couple times a year I figured for a one time flush I would get it up to 3-4 lbs again, which would puts 3-4 lbs of pressure on the wet returns I believe. I would then close the valve before the loop (that valve I dont have) but only during the time that I was flushing the system. Then I would open that valve that I do have (the one with red arrow in picture), and the 3-4 lbs of pressure in the system would force the water and crap out. That was the theory anyway...

Fred said:

I also beg to differ with you. That pipe with the blue handle/drain on it is on the wet return, just before it goes up to the Hartford loop.

I think the valve your talking about is the one with the red arrow pointing to it. That's not what I was referring to.

What I meant was NOT a wet return is the other valve above and slightly to the left of what your referring to. The one I am referring to is connected to a much smaller diameter pipe, which is part of a hot water heating loop that routes through baseboard on the opposite side of the wall in the background. It heats the basement.

Thanks for sharing your thoughts

SteveJones

JUGHNE said:

The process I described would not require cutting into the copper. Also no pipe threading as nipples are available to fit between your union and ball valve, maybe a coupling depending upon what lengths are available.

Back flushing up into the main could push debris into your main vents causing them to not seal tightly. Same for rad vents if you really get carried away. All venting devices have a max pressure rating to prevent damage to the floats inside.
Actually you could remove your main vents and depending upon your main piping arrangement, you could very carefully inject water thru the vent tapping......matching the water going in to the water going out. This necessitates the need for a large straight ball valve lower drain.

I would guess most of your crud has passed to the lowest point of the wet return right at the boiler. Just like a trap under a sink collecting junk.

You may have read here of a boiler blow down where you isolate the boiler with valves, build pressure into the pounds range, inside the boiler only, and then open a lower boiler drain to blow down the lower area of the boiler.

Good feedback, thanks.

I actually have the main air vent off right now and was thinking about what you described as a possibility. Nice that its early fall, not winter now....

I also was thinking most / all of the crud is in the lowest spot of the wet return as you described. But I think that actually is far from my boiler on other side of the house, which is the part of it that runs under the concrete floor (going under a doorway).

SteveJones

KC_Jones said:

I ask because copper wet returns typically stay much cleaner.

Oh, thanks. That's encouraging since mine is all copper now and I'm definetly considering putting this off until next year! LOL