size pipe for dry return

itzasean

Hi I have a question. What size pipe should my dry return pipes be? Right now they say 3/4 on the price tag still attached and I think thats the inside diameter. The Horizontal runs that leave the boiler measure 1 3/4 "outside diameter" then at the end of the run its a Tee. The top goes to a riser and the bottom is reduced to fit the 3/4 return. My concern is that the water being returned is having a back flow causing the rads to take forever to heat up. I don't have any water hammer but those rads do take a while and on a below zero day they hardly work at all?

JUGHNE

Is this a one or two pipe system.....that is how many pipes connect to the radiators.
Slow heat is usually an air venting issue.

itzasean

1 pipe and i have good size vents on all rads and a monster main

JUGHNE

By horizontal runs from the boiler do you mean the steam mains? 1 3/4" OD might be only 1 1/2" pipe.

Are your steam pipes insulated? How about some pictures of piping and boiler? And location of main vents.

itzasean

I'll post a video soon.

itzasean

https://www.youtube.com/watch?v=jSHtCPSS0mI&feature=youtu.be see video

Jamie Hall

3/4 inch IP is probably adequate -- though not much more than that -- for a dry return -- provided the venting is also adequate. Which it may not be, as @JUGHNE says.

You might check your pressure, too -- no more than 1 to 1 1/2 psi at cutout.

Fred

That's more of a drip leg than a dry return. I assume that is the low spot at the end of the main. Where are your main vents located? I didn't see any at the end of that main. I suspect the problem is poor/inadequate main venting. You say there is a "Monster Vent" but where is it and is it working?

itzasean

I have a gorton #2 at the end of the dry return

Fred

Is there just one Main and one dry return? There needs to be venting on each Main.dry return. Ideally, on a one pipe system, the venting is somewhere right after the last radiator run-out but at the end of the return is OK too, just a little more air to be pushed out before the steam starts to fully push into the radiator run-outs. Are you sure that Gorton #2 is working properly? How old is it? How long is your Main(s)? The amount of air that must be evacuated, at the beginning of a heating cycle will determine how much venting is optimal.

itzasean

Gorton was put in last season and works. The long main is 25 total

itzasean

See video

Steamhead

3/4" is marginal for that pipe, though I have seen it work. And, as long as it works..........................

JUGHNE

That steam "main" looks to start as counterflow and switch to parallel flow in the finished room. 1 1/2" main (he said 1 3/4" OD) looks to have at least 4 take offs. Pretty small???
Slow heat on a cold day is the problem. FWIW

Fred

A Gorton #2 should be fine if that is your only main and it is just 25 ft. As Steamhead says, a 3/4" return is marginal. However, I would think if water was stacking, in that area, you would hear some gurgling or hammer in that area, during a heat cycle. What is your Pressuretrol set at (Cut-in and Cut-out)? The cut-out pressure should not be more than 1.5 to 2 PSI MAX. If it is the standard gray colored Honeywell Pressuretrol, the dial on the front of the box should be set all the way down to .5 PSI (don't try to turn it below that.5 setting or the screw might come loose from the link, inside the box) and the white wheel inside the box should be set to "1". Also, make sure the pigtail (looped pipe the Pressuretrol is mounted on) is not clogged. The higher the pressure, the slower steam moves.

Steamhead

JUGHNE said:

Pretty small???
Slow heat on a cold day is the problem. FWIW

I've seen it work- all depends on the EDR load. If the water can't drain, you'll either get gurgling or banging.

itzasean

https://youtu.be/l9LvlU1CTvE

itzasean

That's a little better video

JUGHNE

When the boiler is steaming on a cold day can you see the water in the sight glass slowly dropping and does the automatic water feeder put more water in? (assuming the water valve is on to the feeder).
If this is the case than sometime after the end of the cycle the "slow" water would find its way back to the boiler and show higher in the sight glass than normal.....(unless you have a leak somewhere).
Continued operation like this would eventually overfill the boiler and produce a lot of hammering.
If the return was slow enough for the water to back up into the steam main there would be water hammer there.

With the union at the beginning of the dry return, that would be the easy spot for an air vent. However you want to pipe over and up as high as possible to keep the return water from ever getting to it as a little surge/hammer can wreck the vent.

Edit: I would try the vent first before changing the piping.

itzasean

Thanks for your help so would you say to add a 2nd vent at that union where the dry return starts or remove the one near the boiler and relocate to the union at beginning of return?

Fred

For just a 25 foot Main, I would move the Gorton #2 you have. There is no need to expel air out of the Returns.

JUGHNE

It looked like there were more than just this 25' return and that single Gorton is venting more than we see.
Some still pictures on the return at boiler would tell more.

itzasean

Will get some later.
On a different note did you see that the 1st half of the main is pitched up before the elbows and then pitched down? Is that ok? How does the condensation in that section get back (same way it left)?

JUGHNE

That is called counter flow piping, steam one direction with condensate flowing back in the bottom of the pipe. Any of your steam pipes that don't have a "drip" or dry return on the high end of the pipe would be counter flow.
The returning condensate from that should be going down into the horizontal header which should slope to the equalizer going into the bottom of the boiler.
The long main with the dry return would be parallel flow, after it goes thru the wall with the 90 and 45. Steam and cond same direction for that section.
Are you sure there are no other return pipes, they could come down from the 2nd or 3rd floor, their connection to the steam line could be closed up in walls or ceilings?

The question always asked: what pressure does the system run at?

itzasean

Here are pics

JUGHNE

So that is the only wet return then? As Fred said you could just move the vent to the new location.
You might have to slow down the venting on the other rads that do not come off of the long main.

I don't see an auto water feeder, do you have to add water manually?

itzasean

No its manual . I add a little water here and there .

JUGHNE

Have you watched the water level during operation when you believe the cond return is slow and backing up?

Fred

Is there any downward pitch on that dry return as it heads back to the boiler? Pressuretrol looks like it is set OK but you need to take it off and check the Pigtail it is mounted on. If it is clogged, it will allow your steam pressure to rise well beyond the settings. What brand/size vents to you have on the radiators? If too big, some of the closer/larger radiators might be hogging most of the steam, at least initially.

JUGHNE

In addition to all that Fred said, the slope of that dry return and also it goes into some wet return piping right at the boiler. What is below the water line of the sight glass is considered wet return.
That wet section acts as a sludge settling point, a trap if you will, and if partially plugged may cause slow return.

That may or may not have been cleaned/replaced when that new 3/4" pipe was installed. Sometimes replacement is easier than cleaning. That wet piping is a place where pin holes show up in return piping. If the outside of it is wet at all then there may be some leaks that evaporate away without forming any puddle.