Missing main vent & high heating bills

delcrossv

Late to the thread, but this is some kind of dripped counterflow arrangement?

SteamingatMohawk

@cross_skier See my message to you.

SteamingatMohawk

Discussion of uneven water levels is in Lost Art, starting on p. 82. It sheds a lot of light on the near boiler piping on the supply side. A few pages before that discussion there is a great discussion of the sizing of boiler steam tappings, dealing with steam velocity, water pickup and a few other things. I always skipped over it, because my boiler only has 1 tapping and arrangement is proper.

If you don't have the book, I highly recommend getting it.

Justin20

delcrossv said:

Late to the thread, but this is some kind of dripped counterflow arrangement?

The short main appears to be counterflow with no drip and not tied to any kind of return. Seems to work fine (has been for the past few years at least).

My issues are really the bulk of the radiators on the long main

SteamingatMohawk

I noticed the single steam supply from the boiler is a 2” pipe (2-3/8” diameter). The PSD-6D manual says,

“3. Boiler is equipped with two 2½" supply connections and two 2½" return connections, one each on both left and right sides of boiler. Plug unused connections with furnished 2½" plug (furnished).

8. Steam riser(s) and header shall be 2½” pipe size.”

I calculated the steam velocity (p. 77-79 of Lost Art) for the existing supply as follows:


Lbs/hr x Cubic volume of steam = steam velocity (feet per second)
-------------------------------
25 x Internal area of pipe


PSB 6D Heating Capacity = 153,000BTU/hr, (from the boiler manual, p. 3)


Heating Capacity = Lbs/hr
-----------------
960


153,000 = 159 Lbs/hr
---------
960

Cubic volume of steam = 24 cubic ft per Lb suggested in the manual

Internal area of 2” Sch 40 pipe = 3.36 sq in.


159 x 24 = 45.3 ft per second
------------
25 x 3.36

This “exceeds the velocity against which condensate can drain. “ There is a more detailed discussion in the book.

The supply pipe is too small. If it was 2-1/2” (4.8 sq in), the velocity would be 31.8 feet per second, which is still too much. Modern boilers of this size operate around 25 feet per second.

The solution is to use both supplies with 2-1/2” pipe, bringing the velocity in half to 15.9 feet per second, which happens to be the velocity for "old" boilers
.
This will reduce the amount of condensate in the steam, preventing things like ”wet steam, water hammer, squirting air vents and uneven heat.”

Consider this when you have the modifications done and make sure the manual is followed.

Finally, the manual covers models from 62,000BTU/hr to 245,000BTU/hr and shows both one and two supply configurations. Obviously, the smaller boilers can use one, while the larger ones need two. It's pretty clear the PBS-6D needs 2.

I hope this helps.

Justin20

@SteamingatMohawk

Thank you for the calculations!! This is extremely helpful

Indeed, i actually have a PDF copy of my Dunkirk manual and have seen that the piping is undersized. The original plumber took a 2-1/2" > 2" reducer right at the supply tapping. I've also read on here that side-tapped Dunkirks are notoriously finnicky about piping.

I believe i can get the 'boiler room' NBP redone to be sized/spaced properly per the manual's specifications. I could even take the opportunity to do a drop header for even 'dryer' steam. What would be a problem however is the main. That is substantially more difficult. As I've mentioned, it's in a finished ceiling, running alongside the supporting steel i-beam of the house. The main is also 2". It also feeds at least 4 other takeoffs that run across the basement ceiling feeding several risers going to the upper floors.

Do you think it would be worth it to just do the 'boiler room' NBP (supply riser, header, risers to mains, etc) while leaving the 2" main as-is? It would be a major job if we had to replace the main.

In the meantime, i have:

- Added 2 B&J BM vents to the end of my main (they're on a 90 elbow due to space but i don't think the steam cares ). There previously were no main vents

- Cleaned clogged pigtail and added 0-3 gauge

- replaced most rads M-o-M vents with varivents (yes i had tried the various M-o-M cap sizes)... THIS MADE A HUGE DIFFERENCE

With the improvements above,my rads now start to get hot in 20-45 min from cold start. This is down from 1-2+ hours.

Known remaining issues:

- Undersized NBP

- 17" A-dimension

- return is not technically at the end of the main. There are 2 rads/risers about 2 feet after it

- pressuretrol is shot (it's set for .5 cut-in with 1 diff - 1.5 cut out). I watched it with my new gauge today. It cut out at 4-5psi and cuts in at 2.5psi. The 0-3psi gauge went all the way to the stopper on the OTHER SIDE OF THE ZERO (!!!)

From reading on here i have ordered some items:

- Safegard arrives tomorrow (cyclegard replacement)

- Vaporstat arrives tomorrow

- Lost Art of Steam Heat is ordered

Photos of my amateur work so far-

Before:

AFTER:

I'm no plumber, be gentle 😁

SteamingatMohawk

One quick comment on your pics. The pressuretrol is probably fairly old and may have a mercury switch. If this is true, the pressuretrol is mounted on the pigtail in the wrong direction. As the boiler creates pressure there is an "unwinding" force on the coil, trying to straighten it. That causes the pressuretrol to tilt and with the existing orientation, it changes the settings because of the angle of the switch changing as pressure rises. The solution for this situation is reasonably simple; just rotate the pressuretrol so that any pressure changes make the unit rotate forward, not sideways.


You said above,

"- pressuretrol is shot (it's set for .5 cut-in with 1 diff - 1.5 cut out). I watched it with my new gauge today. It cut out at 4-5psi and cuts in at 2.5psi. The 0-3psi gauge went all the way to the stopper on the OTHER SIDE OF THE ZERO (!!!)"

What you said, I believe, is explained by what I just advised. I don't have any real life information on how large the effect is, but tilting the whole pressuretrol changes how it works, because the mercury is a "fluid" and changes as the level of the pressuretrol changes from side to side, not so for front to back rotation.

SteamingatMohawk

After doing those calculations, I thought it's too time consuming and maybe complicated and I wanted to do something to make it easier to determine the velocity for different size boilers and different size main supplies. Here is the chart. Take a few minutes to digest it. The line at 25 feet per second is the dividing line above which one steam supply is not enough for a particular size main. Realize small numbers above that may not make much difference.

As I posted above:

Your boiler, assuming one 2" steam supply the velocity is 45.3 (near the green triangle at 150,000 BTU/Hr).

With one 2-1/2" supply the velocity would be 31.8 (near the purple square below the green triangle).

With two 2-1/2" supplies it would be half that at 15.9.

Now here's the new information,

If you used two 2" supplies, the velocity would be half the 45.3 or 22.7 feet per second.

The manual says use 2-1/2" supplies, that is probably based on the largest model of that boiler design (245,000BTU/Hr). Your boiler manual does not suggest using smaller supplies for smaller boilers. The choice between one and two supplies is important for steam quality.

Now, in your specific case, because your boiler is 153,000BTU/Hr vs. 245,000 BTU/Hr. looking at the chart one could determine that two 2" supplies would provide a less than 25 feet per second velocity. Let me make it perfectly clear, I cannot tell you to do that because it is not my place to make such a recommendation. I am merely trying to explain the differences to improve your understanding.

In summary, where the pipe size line crosses the 25 feet per second line is the number of mains goes from 1 to 2. Putting it another way, going up the 2-1/2" line at 110,000BTU/HR one supply is enough and at 130,000BTU/Hr two supplies are needed.

SteamingatMohawk

A common point regarding safety is that any low pressure gauges should not be left in service when unattended. The fact that your boiler overranged the 0-3 psig gauge is exactly the situation that is to be avoided. I urge you to change your arrangement so that the 30 psig gauge is always in service and any lower pressure gauge can be isolated by a dedicated shut valve when not needed to be monitored.

In consultation with a couple of valve manufacturers last heating season, it appears to be common that pressure gauges are only structurally safe up to 130% of full scale (in your case 3.9psig). Note, there are some gauges, like Magnehelics, which can withstand 30 psig.

Depending on how high the pressure in your boiler actually reached, you may have been very lucky. If it went all the way around past 0, it may not read correctly any longer and should be replaced.

Lots of the guys on HH feel the 30 psig is not useful on a practical basis, but it is required by the boiler code.

Justin20

Depending on how high the pressure in your boiler actually reached, you may have been very lucky. If it went all the way around past 0, it may not read correctly any longer and should be replaced.

@SteamingatMohawk That's an excellent point. I will compare the low pressure gauge to my 30psi gauge to check if it's still accurate. If it is, which valve type would you recommend i put before the gauge? There's space constraints so Id prefer something smaller?

The pressuretrol is probably fairly old and may have a mercury switch. If this is true, the pressuretrol is mounted on the pigtail in the wrong direction. As the boiler creates pressure there is an "unwinding" force on the coil, trying to straighten it. That causes the pressuretrol to tilt and with the existing orientation, it changes the settings because of the angle of the switch changing as pressure rises.

I've read this somewhere on HH as well. Luckily this is now moot as I've replaced it with a L408J1017 vaporstat (pics to come). Is it weird that i enjoy hearing that satisfying "pop" air sound it makes when it cuts in and out? 😁

Now, in your specific case, because your boiler is 153,000BTU/Hr vs. 245,000 BTU/Hr. looking at the chart one could determine that two 2" supplies would provide a less than 25 feet per second velocity. Let me make it perfectly clear, I cannot tell you to do that because it is not my place to make such a recommendation. I am merely trying to explain the differences to improve your understanding.

I've given this much thought. I am 100% confident in my ability to add another 2" supply riser off the unused tapping on the other side of the boiler. I'd have to repipe the equalizer so that its 15" or so away and at the end, but it's totally doable.

The ONLY THING I'm less confident in is removing the plug in the tapping (see photos. fyi they are older and don't show the new vaporstat and gauges). I've read enough posts on here to know that removing a plug on a boiler can be a b**ch even with the correct 4 point socket.

If i were to do this... I'd also take the opportunity to separate the mains by plugging the tees that connect them (at the main, not the header of course). I know elbows would be better, but more work for me.

 

SteamingatMohawk

When I looked into the steam velocity situation, I thought that unnecessary upper cross connection could serve as a bit of a "steam chest" (since modern boilers have less steam space built in) and may help in getting drier steam. Just speculation.

What say the true experts?

Justin20

@SteamingatMohawk I've decided to add another 2" riser at the unused tapping and to increase the header sizefrom 2" to 3".

Depending on how much grief the fittings give me (they're caked on for at least 20 years) i may do a drop header.

I'm just waiting for an 8-point socket and some kroil to arrive.

More to come...

When I looked into the steam velocity situation, I thought that unnecessary upper cross connection could serve as a bit of a "steam chest" (since modern boilers have less steam space built in) and may help in getting drier steam. Just speculation.

What say the true experts?

Whether or not i separate the mains is dependent upon if someone answers this 👍

Justin20

I've started gathering the parts for the repipe. @SteamingatMohawk @Jamie Hall can you guys (or anyone really) give me your opinion on this header configuration?

The plan is to add another 2" riser at the other tapping. FYI I was able to remove the 2-1/2 inch boiler plug in about 6 seconds with the massive 8 point socket and an impact gun...

Per @SteamingatMohawk calculations, even though the boiler tappings are 2-1/2, the fact that there's a single 2" riser is a major issue and steam velocity will be improved (reduced) greatly by adding another 2" riser. I'm hoping this will solve my wet steam and slow heating issue.

I'll be doing a dropped 3" header and separating the mains. It will be similar to this photo i got from this site (sorry, i don't recall who's work it was):

Minus the gigantic valves at the main risers of course . I will be taking the new riser across the top of the boiler to then dip down into a drop header.

Here's my current setup for those who don't feel like searching through my previous posts in this thread:

One question I have - due to space cconstraints (the automatic water feeder is in the way) i can only fit about 6" of pipe between the fittings at the vertical "drop" portion of the drop header. Is this ssufficient?

Other recent improvements i can thank this site for - pressuretrol and cyclegard replacements:

SteamingatMohawk

To try to keep the sizing simple for a guy like me, you are saying

2 @ 2" tappings to meet in a 3" header teed to 2 @ 2" mains to the building.

The 3" header will have a slightly lower velocity than the 2s will by about 8%, which is better than keeping everything at 2", as long as you can make the arrangement fit. However, for that short length, it may not make a lot of difference. If you kept the header with 1 @2" instead of going with 3", it would be like a highway going from two lanes to one, then back to two, but the speed in the 1 lane would be twice as much.

The real experts can comment on the practical effect, if any.

I am no plumbing layout expert by any means.

For anyone who may want to calculate the velocity difference, the Sch 40 2" pipe has an area of 3.3556 sq", the 3" pipe has an area of 7.3927 sq".

SteamingatMohawk

Don't forget to do the right thing with the overranged low pressure gauge. It's not difficult.

veteransteamhvac

Good luck getting that plug out. Please let me know how you manage it.

I recently repiped a Dunkirk/Lennox boiler of similar size to a drop header configuration. It was a single 2" riser with 2" header and 2" main with no equalizer and no drop header. This was to solve quite a bit of pipe banging among other issues. Simply adding the drop header and equalizer has made enormous difference. There is still some surging going on but no banging and the system is operating fine. Would a 3" header be nice, yes, but for this situation the best bang for the buck was this rather simple repipe.

Are you sure that is a 2 inch elbow from the side of the boiler? It looks like a 2 1/2 - 2 reducing elbow.

If I were you I would just repipe to a drop header with a proper equalizer and main takeoff first and see how that works. I suspect you are going to have a hell of a time getting that plug out, perhaps not. If the output is in fact 2" I would not worry about going to 2 1/2 inch risers at this point.

I was talking with the Burnham boiler steam manufacturing rep at the AHR last week and he said that going forward all of their boilers will have 2 inch vertical tappings and then a specified header size of 2 1/2, 3, etc depending on the size of the boiler. I'm going to presume they understand the workings of steam coming out of their boilers and so 2 inches is fine.

Justin20

@veteransteamhvac see my last post:

The plan is to add another 2" riser at the other tapping. FYI I was able to remove the 2-1/2 inch boiler plug in about 6 seconds with the massive 8 point socket and an impact gun...

I read many posts about the pain of getting boiler plugs out so i decided to forgo the wrench with cheater and possibly rounding the edges of the square plug or even tipping over the boiler (!!). Instead i searched around for a 8 point impact socket for a 2-1/2 plug (1-1/2 square sides).

My 10 year old cordless Milwaukee impact gun made quick work of the plug. It was out fairly easily.

My existing configuration actually has an equalizer, although i suspect the header is incorrectly pitched away from it slightly.

I'm hoping the 3" drop header and additional 2" riser will solve my wet steam and slow heating issues. I've already installed 2 B&J BM main vents and replaced my cyclegard with a Safegard.

I hope to complete the repipe in a day or 2. The toughest part has been cracking the existing connections. That dope caked on for decades becomes like cement. I'm actually seeing some pipes deform but still not budging even with 4' cheater. Time to take out the sawzall...

@SteamingatMohawk

Will do

Don't forget to do the right thing with the overranged low pressure gauge. It's not difficult.

veteransteamhvac

Justin20 said:

FYI I was able to remove the 2-1/2 inch boiler plug in about 6
seconds with the massive 8 point socket and an impact gun... I'm hoping the 3" drop header and additional 2" riser will solve my wet steam and slow heating issues.

That's awesome, I wish I had some of your luck! I don't think there's any doubt your repipe will result in better quality steam.

SteamingatMohawk

@veteransteamhvac If your boiler is much larger than 84000BTU, a second 2" tapping would reduce steam velocity and may go further is solving your issues. You mentioned only 1 main, true or false?

veteransteamhvac

SteamingatMohawk said:

@veteransteamhvac If your boiler is much larger than 84000BTU, a second 2" tapping would reduce steam velocity and may go further is solving your issues. You mentioned only 1 main, true or false?

There was only one main, 2 inch. But as I mentioned this repipe was limited in scope due to the desires of the customer who did not have a large budget. They indicated in the future they might wish to do the second riser. But the system was operating quite well with just the one as the water hammer was eliminated.

Justin20

An update in pictures (in no particular order)... almost done. 2 full days work with plenty of back and forth running to the plumbing supply for nipples, fittings, etc.

BEFORE

I'll be creating a new thread for before/after experience and commentary once completed..

SteamingatMohawk

Is the handle of your pipe wrench where you store your cheater or did the wrench fall into it?

When you are done, show us the gauge antler with both gauges and the isolation valve for the low pressure one.

Justin20

SteamingatMohawk said:

Is the handle of your pipe wrench where you store your cheater or did the wrench fall into it? When you are done, show us the gauge antler with both gauges and the isolation valve for the low pressure one.

It fell in there. Can you recommend a good isolation valve type for this purpose?