Wet return question

Timco

So in designing a re-pipe for a large steamer, the existing wet return is not very far below the water line, and is only really 6 feet long or so from the drop down from ceiling to boiler. Is this enough wet return to keep the boiler satisfied during a heat call? Very long building, no auto feeder. Other wet returns I have seen are very long with lots of volume of water to feed the boiler.

Tim

Brad White_203

I think the question would be

how accurately will the new waterline be maintained? If the actual operating WL drops seven inches (who knows, despite your best efforts), it would then likely become a live steam line and mess things up.

If you could drop it to a more positive low point, I would do so.

I had a client's house where the waterline was bouncing around enough to make that happen. Hammer time and an entire wing went without heat until that pipe was dropped. Then all went well.

Timco

Currently the dry returns hit the boiler room, and drop down to become wet about 6' from the boiler, and even then are about at the level of the base of the boiler. There is room to drop them to the floor, but am I missing the point? Won't the wet return not have the needed volume to keep the boiler satisfied during a heat call while steam is several hundred feet and 4 stories away? Should I consider some type of solenoid feeder and a Hartford Loop before a boiler feed tank? On a gravit return, it is the returning condensate that pushes more water into the boiler to maintain the waterline, correct? The old boiler had 5Xs the water volume of the new boiler...

Tim

nicholas bonham-carter

give gravity a try!

before doing the auto-feeder thing, why not pipe it up as gravity, and let it tell you if it's happy or not.

our boiler was never really happy, until we dropped the 6 dry returns straight down to the floor, and then into the wet return. if there is any horizontal at an aprox height of the waterline, the water will be "hidden" as the condensate rises due to pressure in the returns. that situation was a mystery until i connected a clear tube to the return and watched where the return water-level wsa.

right now we have 1,050,000 btu, 54 rads, and no auto-feed--all gravity!! am i happy. hopefully you can make this gravity too. maybe a reservoir tank is in the cards too.

one thing to consider: increasing the volume of the returns doesn't compensate for low water content in the new boiler[ it's to far under the waterline], but low pressure does.good luck--nbc

Brad White_191

According to my tables, a wet return

has twice the carrying capacity of a dry return. That alone would sway me. Of course a means for flushing out is essential. But wet returns otherwise do not undergo a personality change from time to time.

Timco

So as I understand y'all, dropping instantly to the floor and creating a wet return as soon as possible in the boiler room, and making it 2", and running at low pressure (2psi or less) should give a mil btu boiler enough water to keep the line up while waiting for condensate to return? (with Hartford loop, equalizer, and proper header of course)Is there a schematic for the optional reserve tank referred to? Thanks for the return lessons, I think I have the header & supply down...

Tim

nicholas bonham-carter

reservoir tank for 1-pipe system

here is the w/m reservoir tank info:

http://www.weil-mclain.com/downloads/literature/eg/egboilermanual.pdf

page 16 shows the w/m version of this. even though they have a disclaimer for boilers over 500,000 btu, i think it will work, and so does gerry gill:

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=426686&_#Message426686

the idea is that the tank duplicates the conditions of waterline height, and pressure in this outside reservoir.
but remember that only the relatively shallow horizontal band of 3 in. can be used, so the horizontal centerline of the tank is just slightly under the height off the floor of the boiler waterline. in my peerless the waterline is 40.5 in. off the floor, and so is the waterline in the tank.the lwco cut-off point is 36 in. so any water in the tank below 36 in. off the floor cannot flow UPHILL to the boiler. this is why you can have a 6 in. full wet return on the floor, and still have no water in the boiler. the ideal tank would be a rectangular shape: 4 in. high x 18 in. wide by 48 in long [4x18x48 divided by 231 = gallons].

you can also leave convenient ports or unions in the returns for some sort of auto-fill system [just in case it can't keep up].--nbc