Header Design

VTsteam

Have used the search function and didn't find an answer. If building slope into the header, is adding a horizontal Tee with an elbow acceptable to achieve vertical supply lines? Also, system has a 3" and 4" supply lines for different zones. Is it preferred to have (2) supply lines off the header, or a Y-fitting then into the supply lines? Application is 19 HP commerical boiler operating at 5-10 PSI

Steamhead

1- No. A horizontal tee will let water run into the supply line, where it will carry out into the system. But if you came up from the tee at a 45° angle and used a 45° elbow to get to vertical, that would work fine.

2- Each supply main should have its own tee. If the largest main is 4", the header must be at least that size.

Is this for a heating or process job? What make and model is the boiler?

VTsteam

Application is steam heat. Boiler to be Burnham V905A. Manufacturer advises 24" minimum header height above water line. I have 13 ft ceilings. Is there an ideal header height?

Steamhead

Sure- as high as you can get it. The higher the header, the dryer the steam. 24" above the waterline is a minimum.

And do not reduce the header size below what Burnham recommends.

Why is this system running at such high pressures?

VTsteam

The 4" dia leg off the header supplies 2, large air handlers. At 2 PSI the heat exchangers are not effective. Air blown across them is cool to the feel. Manufacturer advises increasing system pressure would yield greater heat.

EBEBRATT-Ed

If you run the header with no pitch and it's piped correctly you will never have an issue. The header and risers sized properly with the boiler tappings first the system take offs second and the drip or equalizer at the end and you will have no issues.

But thats just me. I don't like crooked or dropped headers. never had a problem with a straight one if piped right. Things can be over done and over complicated

JMHO

Steamhead

VTsteam said:

The 4" dia leg off the header supplies 2, large air handlers. At 2 PSI the heat exchangers are not effective. Air blown across them is cool to the feel. Manufacturer advises increasing system pressure would yield greater heat.

Sure it's not an air-venting problem? How does air get out of those coils?

Danny Scully

@EBEBRATT-Ed, you don’t like drop headers? Maybe you should retire you sound senile

VTsteam

Giant squirrel cage fans are blowing recirculated air across the heat exchangers or coils. Other than the coils themselves there is no resistance to air flow in the system. Air circulation within the room is noticeable.

Steamhead

No, no- how does the air inside the coils get out so the steam can fill them?

AMservices

> @Steamhead said:
> The 4" dia leg off the header supplies 2, large air handlers. At 2 PSI the heat exchangers are not effective. Air blown across them is cool to the feel. Manufacturer advises increasing system pressure would yield greater heat.
>
> Sure it's not an air-venting problem? How does air get out of those coils?

What steamhead is asking, how is the air getting out of the coil so steam can get in?

How is the return piped coming out of the coil?
Is there an f&t trap draining into a dry or wet return?
Does the return pipe have to go up hill to dump into the return?
Can you tell us the dimensions of the coil and the cfm of the blowers?

Unless there's certain circumstances that require a higher pressure ( for example, the coil is under sized for the blower or condensate needs pressure behind it to push up hill into a dry return) 1 psi in the coil should heat the space.
Where are the air vents for the steam system?

The Steam Whisperer

Yes, take Steamheads advice. We have steam coils that are heating buildings with only ounces of pressure. Maybe undersized steam zone valves (if you have them)? I know Johnson controls liked to use tiny zone valves on steam systems and then you would need to run 5psi to get the coils to heat fully. Cheaper valves helps you get the job.

nicholas bonham-carter

What manufacturer would give you such wrong advice, (jack up the pressure)?—NBC

VTsteam

Here are photos of the air handler coils. Both air handlers are Carrier product. No BTU identification. Performance of the 2nd floor unit (first image) and tandem 3rd are mediocre. 3rd floor single coil (last image) is useless. Have disassembled and cleaned all steam traps and rust filters. All supply lines are very hot. Had a Carrier representative and 3 local heating contractors advise raising steam pressure with new boiler install. Thoughts????

AMservices

No vents on the f&t traps.
Have you seen any vents on return lines near the boiler?
You should plan on replacing the guts in those traps. Even though you clean them the elements may be broken.

Steamhead

Those look like later model Webster traps. Barnes & Jones or Tunstall should have parts for them.

Once the air passes the traps, how does it exit the system?

Where is this job located?

VTsteam

Thanks for the feed back. I have confirmed traps are functioning well having replaced a couple as necessary. Condensate exiting the traps gravity feeds a condensate pump, then back to the boiler. Job is in Southeastern Vermont. Not any local talent with these systems, and as machine shop/building owner am now forced to wear another hat.

AMservices

There should be up open air vent on the condensate receiver tank.
Some pictures of the Tank and piping around it please.

VTsteam

Here's the condensate pump.

AMservices

As long is the air can be pushed out of the coil, through the trap, down the return to the condensate pump and out that air vent, it should work.
I would check to see if the horizontal portion of the condensate tank vent is clogged or if water is being trapped between the f&t's and receiver.

One test you could do with disconnect the f&t and blow air down the return line.
If you push through water, You will feel back pressure Just before you blow through it.

If all your tests come back good then I would say add air vents to the f&t's.

VTsteam

I think the system is free of clogs. This past heating season the boiler was leaking so badly I'd have to add water every few hours. Once I got distracted and left the fill valve on completely filling the system until water puked out the condensate vent.

AMservices

I hate to say this but, Because the Steam coils have been seen an excessively high pressure, the high temperature could cause fractures on the coils from over expansion.
From the looks of it they've been leaking. Adding too much fresh water will kill the New boiler with in a few years.
Those leaks need to be fixed before starting the new boiler or Prepare to repeat history

AMservices

https://forum.heatinghelp.com/discussion/164962/warner-webster-steam-system
Here's a Burnham v-9 4 sections I installed this year.
System had some leaking returns.

I do drop my headers.
It helps keep the water in the boiler and dry steam in the system.
Not a cure for dirty water. I've seen water siphon right around those turns.
I did calculate the steam exit velocity and came up with 21 feet per second. That's using both 4" tapping and a running pressure of 1 psi. Even though burnham's book said I only need 1-4" tapping.
A velocity higher then 17 fps will experience carrie over.
I'm sure your 5 section boiler would benefit from a drop header.

VTsteam

I'm more than receptive to any suggestions. Had planned to follow the Burnham manual guidelines, but if a drop header offers greater efficiency see no harm done, right? As I have 13 ft ceilings, was going to have a header height of 36". If a drop header, what height is best? Is this discussed in the Art of Steam text book I've ordered?

AMservices

Oh yes! It's all in the LAOSH.
more then 24" from the off the boiler block is showing off.
Mines 26" with the 2 union's

EBEBRATT-Ed

@Danny Scully

I can only hope to be as smart as you someday.

Your a real professional

Danny Scully

You may be getting old @EBEBRATT-Ed, but you still have that sarcasm down pat

JUGHNE

Could the float portion of the F&T be working, but the Thermostatic air vent stuck shut?
The high pressure might push some air out with the condensate when the float rises.

Steamhead

JUGHNE said:

Could the float portion of the F&T be working, but the Thermostatic air vent stuck shut?
The high pressure might push some air out with the condensate when the float rises.

That's one of the first things I'd check.

Jamie Hall

Check the various guys above -- @Steamhead , @AMservices , @JUGHNE . The clue is that the returns from the coils are cold. Either air in those coils can't get out, or steam can't get as far as the coil; if steam got in there, the returns would be at least warm if not downright hot. Most likely air can't get out. Have you tried this experiment? Turn off the fans on the air handlers and run steam to the coils. They should reach 212 all across the coil -- or very close to it -- very quickly if air is getting out and steam can get in. Don't let them sit that way... they won't like it. But it's worth a quick check.

VTsteam

Thanks for the tip on the experiment. I have done exactly that and see little temperature rise in the coil. Even opened the drain plug on the steam trap expecting to see live steam. Hardly a whisp. Mostly a dribble of warm water. Yet the coil supply side remains too hot to touch. This remains the problem with 2 of the 3 coils. The tandem coils pictured work perfectly.

AMservices

Did you clean the "y" strainer?

ratio

Shoot the face of the (operating) coil with a thermal camera of some flavor. Sounds to me like there's a restriction somewhere between the inlet & the drain on the trap, or the trap is stuck nearly shut.

Check the strainer like @AMServices suggested, then get steam up with the strainer open. That should confirm if the coil itself is plugged.

Get some measurements of the coil & airflow; we should be able to make an educated guess of whether the coil can actually perform.

It's possible that the system does indeed need to run at 5-10 lbs (≈ designed for those pressures), but that's by no means common and isn't very desirable.

EBEBRATT-Ed

@VTsteam Maybe I have the answer but I need more info.


OK I should have looked at the pictures first. Those are non freeze steam coils that have frozen internally. I have seen this many times. They most likely will not leak steam or water.

Easy to troubleshoot. Go to one of the coils that does not work. get the steam valve and control valve to the coil open and with the steam on go to the far end of the coil and put your hand on the tubes. If the coil is broken internally the ends of the tubes will be cold or near room temp. (depending on the air temp across the coil)

So with a bad coil the header will be hot the tubes at the far end will be cold

Now go to a coil that works and do the same thing. You will find those tubes hot

You can go online and google "non freeze steam coils" and find a drawing of the internals.

Its a tube within a tube. When the small condensate tube freezes the steam short circuits and the coil wont heat. All tubes could be frozen or just a few.

VTsteam

Ed, we are on the same wavelength. Tried to do some homework before posting here as a last resort. The coil that works fine is typical of a car radiator with a distinct inlet and outlet. As you describe, the non functional coils are a tube within a tube. Bit confused by the "frozen" description. Are you saying that sometime in the past the coil was filled with water and froze during the winter rupturing internally? A local contractor tells me they only work at higher pressures.

EBEBRATT-Ed

In one of your pics is a horizontal coil. Those are always trouble.

I have a picture of the coils internals but can't find it.

Some rules for non freeze steam coils (from experience)

Stay away from horizontal coils if you can.

Make sure the freeze stat works. The best way to protect the coil when the freeze stat trips it should shut down the fan, close the outdoor air damper and open the control valve to full heat

Make sure the dampers close tight a possible

Never "lift" condensate from a steam coil especially if the coil is subject to outside air

Keep the steam trap below the coil as much as possible. 12-14" is minimum, more is better,

Always use a vacuum breaker on a steam coil. Even with the control valve throttled the coil can go in a vacuum,(from condensing steam) condensate can hang up==freeze.

To answer your question yes, usually the smaller tube inside the larger tube w ill freeze first causing steam to shorcircuit inside the coil=coil wont leak but wont heat either.

Steam pressure will vary depending on application, no hard and fast rule 5-10 psi is not unusual

Yes it froze in the past

believe me the first time I ran into this problem 4 or 5 people before me couldn't figure it out. It took me a while I struggled with it until I found out how those coils are made