Collapsing steam in main radiator slow to heat

have you skimmed the oil from the new piping out of the boiler? was this a problem before you change the piping?

"The last of the 90s is a 1” to 3/4 reducing 90." where is the reduction if the reduction isn't creating a bump in the horizontal to collect water it should be fine.

can you circle this in a screenshot or something? i don't know what you're referring to:
"If you see the one pic of the boiler there is a 2 “ that runs from the bottom to a tee in the take off on the top to the boiler . "

there is a small possibility there is debris in there but it is most likely just pitch trapping water. or a reduction in the horizontal that is trapping water. the water pocket will keep collapsing the steam until it absorbs enough energy from the steam to evaporate so it will eventually heat but it will be severely delayed.

I hate to think this, but the boiler picture, is the header pitching up to the equalizer ? or is that the picture?

how closely is the boler sized to the rad EDR?

wonder if insulating would help,

Is that the old equalizer tht was left in place? Not an issue if it is. Does the supply from the boiler coming up into the tee? And the top of the tee feeds the new header.

I would disconnect the problem rad and take the elbow or valve (whatever is at the top of the riser off) and dump a bunch of water down it. Maybe even use a garden hose if you can and flush it out. Worth a try

Either the boiler isn't running long enough to heat the problem rad or something isn't picthed right is my guess.

Ok. So I think what your saying is the main is full of water and when you open the valve by the vents you get water,?

If that is the case the end of those main needs a drip. Take the 2" 90 off the end and put a tee on it and pipe it into a wet return. But it doesn't look like you have a wet return.

Looking at the pictures of the boiler with the old header the main on the left looks counterflow (supply lower at the boiler, pitching up. The supply on the right looks flat of course it could be the camera angle. Which main is the problem rad connected to?

Theres ways to fix this. Do you have a return that is lower that the 2" elbow at the end of the main that you can get a pipe to?

if the mains are counterflow there should be drips at the boiler although it will probably be ok without them.

Just so we are very clear. You have a counterflow "main" that is currently 1 1/4" pipe?

At what point does it reduce down to that size and how many radiators is it feeding?

The only thing that caught my eye is the new header on the boiler looks pitched backwards really bad, but that could easily be the picture fooling me.

It should be pitched towards the equalizer to drain otherwise it's going to hold water.

I'm guessing it's fine, but wanted to mention it just in case.

You don't want the header holding any water.

Realistically, any pitch would be nice, even level would probably work but not pitched backwards.

I'd also add what I was eluding to above. 1 1/4" pipe seems woefully inadequate to be used as a counterflow main unless it was simply the runoff for that single radiator, which it appears it is not. For me a counerflow should be a full 2" until the end. The trapped water is indicating something isn't adequate either the pitch or the pipe size, or both. I can't think of anything else, but with the group think around here maybe someone else can.

Looking at the boiler specifically at the return drop it looks like you have two returns tied together above the water line. This isn't good. Next time start the boiler with the pipes cool or at lest not steaming. Those two returns should be connected together below the boiler water line. See if one return is getting steam hot before the other,

You may be pushing steam from 1 return to the other causing back pressure on the other rad which is the last one on that main. I would suspect the return with the problem rad may be cool and the other one is hot.

Also we need some radiator pictures. Do you have steam traps on the radiator outlets?

As far as water collecting in the problem main if it is truly counterflow it should be lower at the boiler and pitch up all the way to the end problem rad . If it is not pitched enough you would need to drip the end of that main.

As @KC_Jones rightly mentioned 2" is the smallest pipe used on a counterflow main. Counterflow mains need larger pipe for a given steam load that parallel flow mains.

Either way the the water needs to be able to get out.

I am wondering if the problem rad is heating through the return?

Where are you located?

are you sure the boiler isn't surging from the oil from all that new piping? is the water line bouncing in the sight glass or is it only moving a little? if you get water out of the main with the boiler off it isn't surging

closing off all the radiators on that main is going to make things worse, all the output of the boiler is trying to rush toward those vents

it is pretty rare for a boiler to be too small but it is very common for a boiler to be 50%-100%+ oversized. on a 2 pipe system a boiler that is too small just means that all the radiators don't heat fully, the system can still be balanced as long as the boiler matches the heat loss of the building.

you have to check the main for a dip, it has to either be a dip or some combination of reducers in the horizontal that is holding water in the main if water comes out with the boiler off.

if you add a steam trap or drip at the prpblem main/riser connection it could follow the dry return with pitch until it gets to someplace it can drop individually in to a wet return. you could connect it to the dry return with a steam trap if the dry return is lower than the main

you could have debris in the main that is acting as a dam to hold water. it is uncommon but it can happen especially if the system has been flooded.

Correct. And t isn't the problem.

Let me try this one more time.

One. Radiator does not heat or rather heats very very slowly.

Two. There is a valve which is connected t te main which feeds the nonheating radiator.

Three. When you open the valve about a quart of water pours out.

Four. After the water pours out the radiator heats just fine.

Am I the only one who sees some sort of connection here?

Like… arrange to allow the water to escape in the first place and you don't have a problem?

Yes, there may be problems elsewhere in the system. There may be some odd near boiler piping. And so on.

But the problem is a radiator which doesn't heat. Which is proven to have water in the main leading to it. Which heats just fine when the water is removed.

C'mon folks…

I said that last night, but apparently nobody reads. @Jamie Hall, I agree with you.

The main far end is too low or the middle it too high making the end too low. If the dry return is lower than the end of the main a condensate loop could be added so that part of the main drains to the dry return.