Old Bryant steam boiler, and duty cycle

Precaud

JUGHNE said:

A water slug or debris can head for the vent and plug or damage it. As I think more about your vent a 6” nipple would suffice.

Hmmm. If it makes any difference, the vents would be the only thing connected to the take-off pipe that the stub is connected to. The other end is capped. So the only time anything would be "flowing" toward the vent(s) is when the vents are open. I don't see how a water slug could reach it.

What concerns me about this idea is: Since the stub pipe is tilted, extending the length of whatever is added to it will reduce the headroom. So I thought the more compact the arrangement, the better.

Would this give more head room for vents?

Maybe I'm wrong, but it looks like a wash to me.
EDIT: OK, I think I see your geometry now. The reducing 90 + 45 street + 6-10" nipple puts the elbow for the vent(s) behind the stub pipe end, avoiding headroom reduction from forward extension. If the ceiling were tilted, that would work to add headroom. But in this case, it doesn't add any.

Straight connected vents would more desirable as they can drain any water down.

OK, I see. You're concerned that the angle vents might retain some water. Why is that important here, but not in a radiator?

Precaud

I also just found this post, from Steamhead:
https://forum.heatinghelp.com/discussion/comment/1213098/#Comment_1213098

"We do use Gorton D vents on mains where there is not enough room for the usual main vent setup. The 1/8" pipe connection is about the same size as the vent hole, and is enough to get the job done."

Unless I hear a compelling reason NOT to do it this way, I'm going to order the parts manana. Yes, it's a compromise... 3 D's are no Big Mouth... but they're a heckuva lot better than no vent...

I think I can reduce to 1/2" instead of 3/4" and save some weight, too.

Jamie Hall

I think your idea of Gorton D's on cross fittings -- so that they were essentially level with the pipe -- would work, but as @JUGHNE suggested, put them on longish nipples and try to avoid having any of them have a straight shot back into the main. It's going to look a little odd, but I think if you get creative it will work.

Precaud

Thanks @Jamie Hall . Just to be clear, the cross will extend several inches off the end of the 4" stub pipe, which is connected to a now-dormant 1.25" take-off pipe, which connects to the main 14 inches away, and comes off the top of it. That is not a "straight shot" to the main, is it? It impresses me as being better protection than a few inches of 3/4" nipple at the top of an elbow into the drip of the return...

This is a temporary arrangement. Once I connect the header drip pipe below the waterline (this summer, I hope), then the mains venting can be reevaluated. It will then be a realistic option, if desired, to have some venting at the main return end.

I appreciate @JUGHNE 's suggestion, I just don't see that the problem it solves exists to the extent he does.

How's that for denial?

Precaud

I did the main vent "open pipe" timing test tonight. The solar heaters had taken over by 8:30am, so the boiler and piping had been idle all day and were cold (basement temp 65º).

From a cold start, I waited until I felt heat at the header, and started the timer. Standing by the open vent pipe 45 ft downstream and waiting for steam to appear; I was expecting a constant stream of some significant air flow in the interim, but it was quite gentle, almost imperceptible at times. I then remembered: this is a low-pressure system, from a cold start. 8:25 later, the first puff of steam appeared.

How does this compare to other systems with open vent pipe? Is it "in the ballpark"?

ethicalpaul

Air flow will be very slow in the main vent of a cold system since the steam has to do a lot of pipe heating in every foot it advances (“panting” is common)

A better test is from a warm system that fired in the last hour. Especially with insulated pipes.

Precaud

Ah, OK. I thought that comparing from a cold start would eliminate other variables, but I see your point.

Jamie Hall

But to answer your direct question -- yes, that seems about right.

Hap_Hazzard

If you're going to be doing this for a while, here's something I've found really handy.

You can stick the probe under the insulation, if the pipe is insulated, and there's a magnet on the back. There's a built-in timer, and you can set an alarm to go off when it reaches the target temperature. I bought two of them so I could see which of my mains got hot first.

Precaud

That's pretty cool, @Hap_Hazzard . Something like that might be worthwhile once I get my npb straightened out.

Precaud

I'm curious... what do the two controls to the left of the ID plate do? The top one is right at the waterline.

@PMJ , does yours have them? If so, what does the manual say they are?

Hap_Hazzard

Those are called try cocks. They were all the rage before glass gauges were invented. Now can you guess what they were used for and how they worked?

Precaud

So they're not controls, but plugs? Visual water level check ports? Nothing coming out of the low one meant add water?

Now I know why they made holes in the side of the enclusure for the sight tube...

Precaud

Tim McElwain said:

It looks like the gas valve (Honeywell) was replaced at some time. The valve has a built in regulator so the regulator ahead of the gas valve can be removed.

Thanks @Tim McElwain and sorry for the delayed reply. I see your point. It is possible that the first regulator was left inline as part of a pressure reduction for high-altitude derating?

Precaud

A 3psi gauge and all the ingredients for the new main vent tree (aka antler) arrived yesterday. Unfortunately they sent the wrong vents (#4's instead of #D's) so that will have to wait.

Since I got a new Pressuretrol (same model), I decided to put it in. After removing the old one, I noticed that the spring for the Main adjustment was fully extended, with something wedged on top of it, quite different than the new one. It turned out to be the indicator for the main pressure. Prior owner had set the pressure cutout beyond the 15psi max and jammed the indicator up to hide it. Yikes. Disassembly and a few minutes of tweaking and the old Ptrol is working fine again.

Since I now have a gauge, I put together a quicky version of @Gordo 's clever pressure tester to compare the old and new Ptrols. (see https://youtube.com/watch?v=mE1-QuUx4_c ).

To shorten the story; by adjusting the Main screw, I was able to get reliable and repeatable cutoff in the 1.5psi range on both units (the indicator read a scunt over zero on both of them).

However, it was a different story setting the differential for the cut-in. The old unit was easy to adjust and engaged quite repeatable at about 0.5psi. The new one was not. Its movement was notchy and inconsistent, and sometimes didn't tip the mercury switch until it rested at zero for a few seconds. Other times it would cut in close to the 0.5psi target.

So what's the diff? The new one is on the left, the old one on the right.



: The new one date code is 9510 (10th week 1995), the old one is 7849 (49th week 1978).
: The housings are different.
: The sufix after the L604A-1169 model number is -3 for the new one, -2 for the old one.
: The sensor diaphragms are quite different. The old one is almost twice the diameter of the new one.

I think this latter accounts for its more accurate and repeatable sensing of the low-pressure cut-in.

So I'm going to stick with the old one, and set aside the new(er) one as a spare.

The iron nipple that the ptrol was screwed on to was totally clogged and degrading. Bad move by the previous serviceman. Everything else was brass, so why chince out on the nipple? The ptrol connection looks very clean. We'll see how it works tonight. And I'll hook up the 3psi gauge and see if pressure is getting through the old LWCO it is hooked up to.

Jamie Hall

Bravo! And thank you for your comments.

Gordo

@Precaud: Well done!
I'm glad to see someone else verifying the poor reset precision on those old L604A (and L404A) pressure controls with the small diaphragms. I thought it was just me ranting on and on about just how bad they were! As I began testing them, time and time again, they were the ones that turned up a cropper.
It became clear that the issue was the small diaphragms not providing enough force to reliably cycle the control linkages in the device. Honeywell no longer makes them that way, but unfortunately, there are still a lot of them out there doing their part to screw up steam systems.
I am so glad you caught yours!

Precaud

Thanks @Gordo ! All possible because of your excellent and entertaining videos! The small-diaphragm one behaved exactly as the one you tested.

Gordo said:

Honeywell no longer makes them that way, but unfortunately, there are still a lot of them out there doing their part to screw up steam systems.

They use a different pressure transducer now?

Gordo

@Precaud: You are most welcome!
In regards to your question, they use the larger diaphragm, which is good (as you found) BUT they don't use the mercury bulb any more (and that's good environmentally, but...) they had to redesign the mechanism around the micro switch, which does not have the helpful mechanical force tipping point of the shifting blob of mercury, which makes the latest models somewhere between meh and bad.

Precaud

Yeah, for reliable make/break over time, I'll take a mercury switch over a mico switch any day.

Tonight I started up the system with the adjusted Ptrol and 3psi gauge installed. Nada. Nothing. There is no pressure getting through the old LWCO. So either it is clogged, or the line feeing it. More to do.

mattmia2

The modern ones use an ordinary switch instead of a mercury switch. The mercury switch requires far less activation force. i think he means the newer ones (with a snap switch or mercury switch) use the larger diaphragm and are more sensitive. you could have used a vaporstat although they are more expensive, they are designed to have the working range for steam in the middle of the scale, not at the absolute bottom.

Part of Tim's comment about the gas valve is it is a newer style valve so it probably replaced a failed valve at some point.

Precaud

If I had real experience with plumbing, I wouldn't need to ask dumb newbie qustions like this.

I'm troubleshooting why no pressure is showing up at the old LWCO. To refresh memory, here's a pic of the setup. The pipe in question is pointed to by the red arrow.


It connects from the tee on the upper feed to the sight glass, to the top of the old LWCO. The copper pipe has 3/8" compression fittings on both ends. Here's what they look like.



After removing that pipe, I verified that:
: The tee is clear in all directions.
: The LWCO is also clear (i.e. air passes freely between the two top connections), with no leaks below them; the bottom 2/3 is filled with water.
: And the pipe is also clear.

By all accounts, this should work. And it should be an ok place to monitor the pressure. But last night the 3psi gauge never budged off zero. Either there's a leak somewhere, or the system operates at near-zero pressure at all times (doubtful).

From what I've read, compression fittings make good, leak-free, pressure-tight joints. Is that true? Do either of these fittings look suspicious?

I'm open to suggestions.

(When the heating season ends I'll repipe all of this, but for now I'm trying to get pressure to the Ptrol and gauge.)

ethicalpaul

You’ve got a good handle on the possibilities. Either there’s a blockage, or there isn’t any pressure building. Take off the gauge during firing and see if steam comes out?

Precaud

Well I just found the leak. It was at the other end of the old LWCO. I was cleaning out the female on top prior to reinstalling the connecting pipe, and apparently pushed down on the float inside. Water is now steadily streaming out of the left side of the old LWCO. It looks like it isn't going to stop until the boiler drains. Damn.

Gsmith

from the age and crustiness, I'd consider a new LWCO

Precaud

That lwco has not been a funtional part of the system fo more than 30 years.

And now its outta there.


Now to see if I can get some pressure monitoring in place before nightfall.

This is my first real plumbing emergency. An adrenaline-pumping experience

mattmia2

That lwco is just being used as a manifold for the current lwco.

Could you plug/cap the fitting on the old lwco body where the water is coming out?

Precaud

Already did, you can see it in the photo. Water was refilled and is holding fine at proper level. Now to Ace to get fittings/adapters for the top tee.

mattmia2

That makes even less sense. so the lwco body was essentially just capping those tees. I suspect those tees were original and capped with the caps being provided to flush and skim the boiler and piping and whoever installed the new lwco removed the caps and put ells there instead of just removing the old lwco.

exqheat

You can adjust the pressuretrol with a dime on the screws on top. I would set the cut in screw to .5 lbs, and the differential screw to 2 lbs. You should investigate the options to deal with the asbestos pipe insulation. Remove the nail, and it may still serve you well. Google the pressuretrol and you will get instructions.

Chris_L

mattmia2 said:

That makes even less sense. so the lwco body was essentially just capping those tees. I suspect those tees were original and capped with the caps being provided to flush and skim the boiler and piping and whoever installed the new lwco removed the caps and put ells there instead of just removing the old lwco.

On a typical setup with that LWCO, there would have been a sight glass at the end of brass tees. It looks like on this system, they removed the sight glass and piped the tees to the new LWCO outside the cabinet--and put the sight glass next to it.

(No surprise the old LWCO it was leaking. Look at all the rust on the left side of it.)

Precaud

Yup, that's where it leaked from.

I put a 3/8" to 1/4" bushing in the tee on the upper feed to the sight glass. The tee comes off at about a 45º angle, a little less, actually. Then a 4" nipple, a 45º elbow, 2-1/2" nipple, 90º elbow, and screwed the 3psi meter onto it to monitor pressure. (Every joint was taped, of course). Fired it up, and it basically performed just as it always has. No indication of pressure, even after the first radiator in the loop was warming up. No movement of the needle at all.

Does this sound normal/correct?

I unscrewed the meter, and yes steam came out, and a gurgle or two of water. So I shut the system off and put a plug in the elbow where the meter was. I've had enough for today. The system will work tonight if needed.

EDIT: OK, I think I misunderstood the pressure thing. I was expecting to see some of it on the meter once steam was being produced and reaching the first radiator, say 15 minutes after a cold start. I just read @Jamie Hall 's description of the pressure process, and I see now that is not the case. I should not expect to see any pressure until the entire system is up to temperature, i.e. all radiators hot and their vents closed.

mattmia2

and the radiators are consuming steam at a slower rate than the boiler is producing it. if the radiation is perfectly matched to the boiler output it will never build pressure. Unless the boiler is very oversized (the steam the piping consumes is also a factor and is baked in to the boiler edr rating a a pickup factor. the actual pickup factor will vary depending on the piping and if it is insulated) it may not build pressure until all the radiation is hot and it had been running for a long time after that.

Precaud

Here's the new main vent installed and working fine, using three MoM #D 1/8" vents. When steam reached it, I was expecting some response time difference between them, but they all closed immediately.



I actually used #4 vents with the orifice cap removed; I ordered #D's but they sent #4's by mistake. On all the MoM radiator vents, the opening under the cap is 0.1875", so toss the cap and you have #D vents.

First impression: I like it, but some radiator vent rebalancing is going to be necessary, especially the radiator on the short counterflow branch.

nicholas bonham-carter

You can see how the main vents are performing, as you watch the pressure on a low pressure gauge. Aim for a back pressure of under 2 ounces.—NBC

ethicalpaul

I’m glad you figured out you can remove the caps. I was going to suggest it but I couldn’t remember if you got MoM or Gortons

Precaud

The main vent has been installed for a few days now, and after resizing the vents on three of the radiators, I've had a chance to observe the main vent's influence on how the system performs. A couple reminders: the vent was placed on a stub located a few feet away from the active radiator furthest from the boiler, about halfway down the 95 ft. long main loop; and on most days the system operates sundown to sunrise, and makes a cold start once or twice.
Plusses:
: Said furthest radiator does warm up and produce heat more in synch with the others, whcih is good.

Neutrals or negatives:
: The system does seem a bit noisier than before. More clunking and thunking as it warms up.
: I see no difference in its "cold start" time, i.e. how quickly the system comes up to temperature and starts producing usable heat.
: Because of the flaw in the header drip pipe connection, steam is now being delivered more quickly through the end of the mains to the inactive radiator take-offs. Which is only to say, venting the main midway did nothing to impact this problem.

So I think I will not see significant benefit from mains venting until the header drip is connected below the water line, where it should be.

Precaud

I now have the Ptrol and gauge installed under the pressure valve (thanks @JUGHNE for the advice).


It was another sunny day, the solar heaters absolutely rocked, and the steam system was dormant from 9am on. Tonight I opened doors and windows to cool the house down from 78F to 70F in order to test the install. I set the tstat to 74, giving it a decent hill to climb from a cold start. Once I felt the main vents close, I sat and watched the gauge until the tsat was satisfied. All of the radiators were nice and hot.

At no time was there even a hint of deflection on the 3psi pressure gauge.

Yes, I know conceptually that well-designed systems aren't supposed to generate pressure. But this bugs me. I just spent a lot of time doing this and it's showing me nada. I don't know for certain that this qualifies as a well-designed system.

Am I overthinking this, and should just acccept its presurelessness?

mattmia2

Pressure is bad, it just means you are heating the steam more than it needs to be, you transfer less heat from the products of combustion when the boiler is hotter. You could clock the gas meter to see if it is firing at the rate on the nameplate. It could be out of adjustment or dirty such that it isn't transferring as much heat to the boiler as it is designed to even if it is firing at the right rate.

when you start from a cold boiler you spend a lot of time just getting the water and the mass of the boiler hot enough to produce steam, it is a while after that when you would be getting the full output. if it were to run a long cycle from a hot boiler it is a lot more likely to build pressure

Precaud

OK, I'll wait for a particularly cold, sunless day to observe it. I guess I still expect to see some small amount of pressure in the system. For example, watching the videos @ethicalpaul posted of his system running (when he was experimenting with his ptrol spring mod), it showed some pressure at all stages of the cycle, and quite a build when vents closed.

Related matters, two things I now see first-hand that you guys have put forward. One is the impact of lifting a vent away from an elbow or tee. Originally, when the pressure relief valve was mounted right on the elbow, if I opened it when the boiler was warmed and producing steam, a mix of steam and intermittent spit of churning/gurgling water would come out. Now, with it mounted some 4-5 inches higher, no water comes out. And not much steam, either. It is no longer in the turbulence zone of the 90. Quite a difference...

The second is how cool the gauge and ptrol remain due to the water in the pigtail. I would expect it to be at least warm from conduction. Pretty interesting.