Equalizer disabled experiment video

Hello @ethicalpaul,

Yes, I totaly agree that with your system as the working example you will have to artificially induce the situation. I guess it depend on if you want to see it or not (and time and cost issues too). With your system you may have to measure the pressure with the resolution in microns to see it. And I agree that with your system running normally measuring the effect may be impossible. And I agree with systems like yours the equalizer's purpose may be simply limited to a header drip. I believe before it was called an equalizer a similar pipe was called a Bypass pipe.

I think what others are trying to say is with other systems that have additional equipment like bigger boilers, zone valves, various traps, condensation tanks vented the the atmosphere the value of the equalizer may be more than just a header drip. And in the eyes of the boiler's manufacture it is 'best practice' for very low cost.

Instead of calling it an Equalizer should we call it the Queen Latifah pipe ? There is a King valve.

Here is how it was explained to me many years ago:

A steam boiler has many uses. One can be process steam. Lets look at this first then we can get back to heating boilers.

Everything is equal here

Then the burner is turned on. The water starts to heat, then boil off the steam.

Then pressure starts to build for the process of baking or something else. Only a few PSI is needed. Lets add a water source and an overflow. The Gas valve fails open, so no electrical current to the valve but it is stuck open. (could have failed mechanically like the church, or a worker could have manually opened it … there were some old valves that you could do that to) So no LWCO is goint to help here because turning off the electric won't stop the fire.

Next thing the water feed can't keep up with the overflow caused by the 5 PSI forcing the water out the overflow that is 10 feet above the boiler. No one took into account that the boiler might ever get to 5 PSI so the overflow was only 10 ft high and water never came out the overflow.

If there was a equalizer and a HL this boiler would never have failed

Now lets look at a heating boiler with radiators

Let's say that two thing happen. The main vent fails open and goes unnoticed for some time. At less than 1/2 PSI it could go unnoticed in a vented crawl space. Then at some later date the gas valve fails open like what happened at the church. The burner will not stop firing. The radiators heat up and keep heating and all the vents close, but the failed main vent allows steam to pour out into the crawl space with enough velocity to cause the pressure drop like shown in this diagram. So steam is moving fast thru the main and the pipe friction loss allows the pressure at the end of main to drop enough to cause the water line in the boiler to be pushed below the safe operating level. As shown here the Equalizer provides a syphon intruption and the pressure of the boiler steam is equal to the pressure of the return pipe and the pressure forcing water up and out of the wet return into the dry return and the lower pressure connection between the dry return and the main. So something needs to go wrong for the piping design to be "needed".

All you need to do is create something where nothing can go wrong then you don't need to prepare for something that might go wrong.

I this a little bit helpful Paul?

Then we need to look at the last section only. So we can agree that high pressure moves tp low pressure. Are you asking "How does the pressure at the end of the main get low enough to cause the water in the boiler to get pushed out the return (assuming no equalizer) ?

Then we would need to go to some engineering manuals and look up friction loss based on steam velocity related to a given pipe diameter.

Any fluid including steam will loose some of the energy it has as it moves thru a pipe. The energy I'm speaking of is measured in PSI pressure.

So the last part of the post states that the flame will not stop. So that means that steam pressure will continue to increase until such time that the energy of the flame and energy of the pressure leaving the system is equal. I'm going to give that a number 5 PSI based on the way that the main vent failed. The velocity of the steam moving out the failed main vent is sufficient to cause a loss of pressure energy by 50%. This is my example so I can make the vent fail at what ever rate I want.

Now steam is building pressure and holding at 5 PSI in the boiler; at the point where the steam is leaving the system the pressure is 2.5 PSI.

That is how this could happen.

If you look at the Weil McLain glass pipe boiler you can see dry steam leave the system to the parking lot when the valve is partially opened. But when the valve is opened more, the wet steam and water will exit the system into the parking lot. Weil McLain's example can be made to show the different velocity of steam leaving to the system into the parking lot by opening the valve less or more to show the point.

Does that help a little Paul?

No Valve. Friction loss, it's a gradual thing. There might be 5 PSI at the first elbow off the header, then 4.5 PSI 10 foot down the pipe the 4.0 PSI another 10 foot further… Did you try the 200 ft Garden hose test yet? That will help you actually see it.

Here's my drawing from years back.

I think that we would be hard pressed to find a boiler that was installed over 120 years ago still in service. So I think that we will be equally hard pressed to find a boiler operting with a desigh that might come close to illustrating that the pressure in a boiler can get high enough to force the water out the return and cause it to stack up in the dimension "A" area of the system. That is because any of those boiler systems have been replaced sith domething new that includes the Hartford or Gifford loop.

All I can say is that there must have been some type of problem that the boiler men/women* at the time needed top solve wnd they came up with what we have today.

*Added that for the benefit of @Subdural Did you see the piping she installed on her boiler… WOW!

T

Wouldn't downstream steam pressure loss (assuming there is any) be more a function of the steam condensation than of friction? There is a 1600:1 volume reduction happening. Potentially much more equivalent to opening a hose😏

Hey Paul, I just want to thank you for taking the time to perform your experiment and for bringing up this question in general. As someone who rarely gets the opportunity to work on a steam boiler I've often wondered why the equalizer is named as it is. Your experiment has been interesting to say the least

While it is true that the drop to the wet return at the end of the main acts as an equalizer and balences the pressure between the supply and return I have seen air vents spit water without an equalizer.

A homeowner had his boiler replaced where the boiler had failed . This system had been knuckleheaded previous to the new boiler install by the homeowner having someone remove the cast iron radiation and installing finn tube baseboard in it's place…….not a good idea. He had been having constant problems with the baseboard air vents spitting water and and not heating…..this was 1 pipe steam and the baseboards were not pitched enough and some of the basebords were very long.

The "fix" we did was to install a return line from every baseboard in the house (each run as a dry return) back to the boiler and then dropped down all the returns were connected below the water line and the air vents were taken off the baseboard and relocated to the top of each drop.

The system then heated well but the air vents kept spitting water.

At tis point the boiler had been installed without an equalizer so we installed one and the spitting stopped immediatly.

This was back in the 70s soI don't remember anything about skimming or haw the header was piped or what pressure if any it was running at…….this was a tiny ranch jhouse. But I distinctly remember installing the equalizer and the spitting stopping.

Ethical Paul, your videos prove your point about the function of the equalizer, I mean a lack thereof.

On my 66' mains, including the dry return my boiler water level of the sightglass ht in approx 7 mins from a warm start drops to 25% of the NWL at a pressure of just over 0.5psi. After this initial drop, water level in the sight glass varies +/- 0.25" until the boiler shuts down on temp.

My PB boiler- one size larger than yours- holds 13 gallons, and based on the external geometry, I am estimating anywhere from 3-3.5 gallons are being expelled into the wet return causing the water level in the boiler to drop. Since my A dimension is 33", the water in the wet return does not block the main vents.

Thus, my equalizer is unable to keep the NWL stable. I have checked and rechecked the oft mentioned maladies here-surging, sagging pipes, improper near boiler piping, leaks, condensation in the rads creating a vaccum, et al, but can't attribute the pressure drop across the mains to any of these except friction.

The frictional losses which result in a pressure gradient across a steam carrying pipe are a function of the steam dryness, viscocity, temperature, velocity, pipe length, pipe cross section and other constants, with steam velocity being the largest contributor. Which of these factors are affected by an equalizer except steam dryness?

Your equalizer has a minimal impact on steam dryness but for the majority of us, steam/water seperation is a compelling reason to have one. I agree with you that the equalization of pressure is being done by the mains and the wet return.

The water in the return must rise up to create a pressure differential to push the water back into the boiler. You need a pressure difference to make the water move. Your working with low pressures so the pressure readings will not vary much

According to chapter 5 of @DanHolohan 's "The Lost Art of Steam Heating", the equalizer was originally called a "bleeder". It was intended to replace a check valve in the return line so the water would not back out of the boiler if a return line broke. Remember, in the days of coal-fired boilers, there were no low-water cutoffs. It's easy to forget how good we have things now.

The problem with check valves on return lines is that they could stick or leak. The bleeder did not have that problem.

It's true that, in normal operation, the equalizer isn't needed. But the same can be said of Hartford Loops, low-water cutoffs, pressure controls, pilot-safety controls, oil or gas primary controls and many other things. We install these, not only because Codes and manufacturers' instructions require them, but because they just might be needed some day- or night, when no one's around.

In the original edition, pages 61-63.