Pickup Factor...

ChrisJ

My system shuts down at 1 ounce. 1.5 to 2 psi is just crazy talk. Vents start becoming annoying at .5 psi

Charlie from wmass

The difference in air temperature around the radiators is going to be a maximum of two degrees as otherwise thermostat would call for heat.

Fred

It may be crazy talk but probably over 90% of the systems out there have Prerssuretrols that, at best, will allow the pressure to build to1.5PSI. I don't get any vent noise, pushing air out. Probably has a lot to do with the size/type of rad vent too. When it gets sub-zero outside, I will get some sucking noises from a couple rads, pulling air back into the system at the end of a cycle. Any way, we're getting into a different topic (albeit related).

Charlie from wmass

90 % of the steam boilers I install use pressuretrols. They seldom cycle on pressure. Everyone has a different opinion on air vent noise. Many clients find it soothing as long as it is very mild.

ChrisJ

Vents should be seen and not heard. You could build a recording studio in my house the way mine work

Charlie from wmass

Your opinion was acknowledged in my post I believe Chris. Others feel differently.

PMJ

DanHolohan said:

This is how they arrived at the radiator ratings. Really no guesswork at all:



https://heatinghelp.com/systems-help-center/how-they-rated-radiators/

Thanks for this Dan.

This section caught my eye:

That’s why the test rooms that the American Radiator Company built were very similar to what you’d find in an ordinary house or apartment back in the day. They took no precautions against heat loss. They didn’t fit the windows any tighter than a carpenter of that era would have fitted windows. They were going for practical rather than academic, and since we still see many of these radiators in service nearly a hundred years later, I’d say they did a very good job.


I'd say they did a good job too.

Actually, reading this helps illustrate what I was trying to point out. And that was that the total btu/unit time that a "full" or any other radiator is putting into a room is equal to the amount of steam it condenses. To stay full just means new steam is being added at the same rate that steam inside is condensing. Being "full" doesn't tell us exactly what that rate is. Using the tables and a nominal room temperature you can get a real good idea. The rest is up to the room it is installed in and mother nature. And mother nature changes things around a bit on any given day. This exercise has showed me that the same radiator can do even a little more past when it first became full. Maybe only a few percentage points while holding the same room temp, but still an important concept I think. I won't being going to the mat with anyone over whether it is 2% or 8 or whatever. It is the concept that is important.

If there is one thing I have learned about steam, it is that you need to pay attention to some pretty subtle things.

ChrisJ

Hatterasguy said:

PMJ said:

I have been able to slowly drag you into admitting that these things are not as exact as you wish them to be. The convection at the radiator is not just about temperature. As disparities in temperatures in the room increase so does movement (drafts) which are impossible to know about. So the exact same radiator will emit different amounts of total heat depending on what structure it is in, how tight it is and all the rest. It will even depend in the same structure on conditions outside on what day. I am not claiming these things to add up to a huge number. But as an engineer with some experience I suspect now it can creep over 10% quite easily.

So this all boils down to how inexact is it since we do agree it is not exact. You seem bent on reducing all these things I brought up by myself and Chris to less than 5% of the whole story and thereby rendering the whole comment line pointless I suppose. I don't know how many pros out there would bet their bank account that they could call what any one radiator was doing to less than 5 percentage points of error under any conditions except totally off but perhaps they would. I'm guessing they would agree that is what the safety factor is for - the uncertainty in all this.

But if you must, have at it with your numbers and minimize for everyone the potential importance of any of the subjects I raised. This exercise has been enlightening for me anyway. It has shown me another way that these systems are actually quite forgiving to a significant amount of extra boiler - confirming what I have observed with my own system for many years.

As engineers, we try to quantify things. We typically don't go into a discussion naked and make the conclusion that we have an inexact situation and, therefore, we can just forget about trying to place any realistic values on it.

Everything we do is inexact, by definition. We design and then we test and then we redesign and retest. Eventually we eliminate all the errors.

So, my attempt was to simply put some values on the different output of the rad when the interior room temperature or the interior wall temperature changes.

Clearly, you're not interested in that so we'll just leave it as another variable that changes the resulting EDR. I don't think that this result will allow you to make a conclusion that the four individuals with much larger boilers, which do not develop any pressure is a function of this variability but that is strictly my humble opinion.

Just curious,
What gauge are you running and is it behind a pigtail?

I can't remember if you tried a commando setup or not.