Challenging situation

Long Beach Ed

Difficult to say without a heat-loss calculation. Sounds like the boiler is undersized or underfired or both. Or piped incorrectly?

If permitted to continue firing, would the ends of the mains fill with steam? If so, perhaps the Tekmar sensor is in a poor location. If not, I'd check the steam output and quality.

You need an expert to go over the installation and sizing, to make certain the boiler can produce enough steam to fill the mains and radiators with a proper pick-up factor.

Long Beach Ed

chip_10

Challenging situation

Apartment owner upgrades to new boiler. Primary objective is comfort of residents immediately followed by improving overall cost efficiency. Boiler is sized by team of consultants supplied with all available info on old system, firing rates and pressures; all building info re: size, windows, radiator sizes, etc. including on site inspections.

Problem following install and testing:
Can barely achieve 1/8 lb of steam at boiler and only 1/10 of one ounce at last of buildings. System is cycling using Tekmar controller.
A. Some residents not warm especially in last 2 buildings B. New system is using more gas in milder winter than old system was last year.

Suggestions?

Unknown

suggestions

How big of the system is this and got any pictures of the job? With your team of consultants, what did they say wrong with the replacment boiler?

Unknown

only the radiators matter on steam

Find out the number he came up with when he measured the radiators, and compare it to the steam output on the boiler label, in the category of "Sq Ft Steam". That's all that matters.

http://www.heatinghelp.com/newsletter.cfm?Id=130

http://www.heatinghelp.com/newsletter.cfm?Id=160

Noel

ttekushan_3

hooo boy.

> Apartment owner upgrades to new boiler. Primary

> objective is comfort of residents immediately

> followed by improving overall cost efficiency.

> Boiler is sized by team of consultants supplied

> with all available info on old system, firing

> rates and pressures; all building info re: size,

> windows, radiator sizes, etc. including on site

> inspections.

>

> Problem following install and

> testing: Can barely achieve 1/8 lb of steam at

> boiler and only 1/10 of one ounce at last of

> buildings. System is cycling using Tekmar

> controller. A. Some residents not warm

> especially in last 2 buildings B. New system is

> using more gas in milder winter than old system

> was last year.

>

> Suggestions?



I certainly hope that the boiler was sized for the connected load, i.e., radiator EDR (rated in charts for various radiator styles) plus piping. In a large facility its often calculated as EDR multiplied by about 1.2. More may be necessary if long runs exist, like your description states with two buildings.

EDR (equivalent direct radiation) is the surface area of the radiators in square feet. Steam at 1psig @215F with a room temp of 70F its about 240BTU/square foot EDR.

The fact that heat loss calculations were apparently done makes me wonder why. As anyone here (or in the books offered here) will tell you, the steam system's first load (and the load that the boiler should be sized for) is piping and radiators and nothing else.

If the decision was made to downsize based on some parameter other than piping and radiator EDR, then the system will run continuously, produce inadequate pressure, be unable to distribute heat to the system's extremities, and generally cost a fortune to operate.

The thought occurred to me that bad steam traps, etc could cause problems, but the old boiler seemed to manage. And if it managed because it was oversized, then the fuel consumption should have been far more than you are using now.

Ratings on the old and new boiler would be helpful.

Furthermore, at what value is "Cycle Length" set on the Tekmar?

Where is the condensate / "steam established" sensor located?

Armed with this info, maybe we can help.
-Terry

ttekushan_3

hooo boy.

I certainly hope that the boiler was sized for the connected load, i.e., radiator EDR (rated in charts for various radiator styles) plus piping. In a large facility its often calculated as EDR multiplied by about 1.2. More may be necessary if long runs exist, like your description states with two buildings.

EDR (equivalent direct radiation) is the surface area of the radiators in square feet. Steam at 1psig @215F with a room temp of 70F its about 240BTU/square foot EDR.

The fact that heat loss calculations were apparently done makes me wonder why. The steam system's first load (and the load that the boiler should be sized for) is piping and radiators and nothing else.

If the decision was made to downsize based on some parameter other than piping and radiator EDR, then the system will run continuously, produce inadequate pressure, be unable to distribute heat to the system's extremities, and generally cost a fortune to operate.

The thought occurred to me that bad steam traps, etc could cause problems, but the old boiler seemed to manage. And if it managed because it was oversized, then the fuel consumption should have been far more than you are using now.

Ratings on the old and new boiler would be helpful.

Furthermore, at what value is "Cycle Length" set on the Tekmar?

Where is the condensate / "steam established" sensor located?

Armed with this info, maybe we can help.
-Terry

ttekushan_3

sorry guys,

I type too slow.

Weezbo

*~/:)

true for you is true for me:)

i am guessing here buh,... you can probably wipe a solder joint with your bare fingers like me..:) typing,..typings been,,,, berry berry bad...to me

chip_10

More Info on this system

Thanks for the replies all. I hope this helps generate any more ideas. Thanks Again.

Here is the info on this system and pictures.

Boiler is in a separate mechanical room 12' below ground level. The Main (T's) in between the first 2 buildings and then is just a straight shot down from the 2nd building to the 7th from there with 3 step ups along the way in between the buildings.

Main header run length is @ 460' and each building is fed from this run .
Each building is approx. 50' x 60' with a main header coming up off of the main and then branching into a 4 loop main running around each buildings basement to feed all of the radiators in the above 2 floors. These loops are progressively vented more and more as you travel up the line to try and achieve a more consistent supply to each building.
The reading of .010 of an ounce is taken with a 0-16oz gauge at the top of the main header coming into the last building just at the bottom of the first floors joists.

---Old Boiler was capable of 6.8MBH but was always ran on low fire which was clocked around 3.2 MBH. Vessel Size of 62.5"W x 113"L x 107.5"H. Steam Baffle was 8" on this.

---This new boiler, (L.E.S. HF3-70) which has now been over-fired 10% because of the lack of pressure, is now at 3.2MBH, This boiler is also modulation equipped with a 10/1 turn down ratio. Vessel Size of 34"W x 68"L x 78"H. Steam Baffle is 6" output on this boiler. Of course with the smaller vessel there is also a condensate return tank to make up for the lack of vessel size on this new boiler.

When new system was installed all the steam traps were replaced to prevent blow by.

The Tekmar Steam Established sensor is located in between the last 2 buildings in the tunnel where it was originally located and functioned properly before and to rule out problems it was changed out with a new sensor. Also called Tekmar and found a technical service bulletin about indoor sensor issues and per the TSB added two more indoor sensors running in series parallel to correct feedback issue as described in TSB. Also tested outside temp sensor and found it to be in good order, but replaced it anyways to again rule out error. The Tekmar is monitored consistently and adjusted sometimes daily to accommodate large temp swings outside. Usually it runs around 11-12 cycles per day to maintain the residents comfort.

Also they are using Macon Controls One-Pipe Steam Valves on all of the radiators on the system. These have been in place for many years before the system was changed. Of course these require (per manufacturer recommendation) that the boiler be cycled in some manner to avoid flooding. The controls in the units with the indoor sensors for the Tekmar are locked at a certain setting so they can not influence the sensors.

So far calls to our consultants and the boiler manufacturer have given the answer of "The system needs to be continually run to generate the steam pressure we are looking to get at the end of the line". **Note: The consultants knew the system was always cycled before the replacement occurred and that the radiator controls were being used and should have factored that into the equations, correct?

I might add that these folks have been using Dickson Data loggers to monitor apt temps for some time now and upon the advice of the boiler manufacturer a test was conducted over 2 days time. Apt temps went up from 72 degrees to over 90 degrees and the gas meter went from using $134.00 per day to using well over $500.00 a day on a day of 20-40 degree outside temps. During the test the controls were set to modulate extremely soon around 1/8 of an ounce to try and control cost and keep temps down in the units. Of course the owner is not at all happy about those results and neither were his tenants as several complaint letters and phone calls were fielded that day.

Any more ideas? Questions? Anything?...

Thanks Again.

Chip

Brad White_9

This may be a dumb-a$$ question but

The steam established sensor- is that actually on a steam line or as I have seen it for cycle confirmation, on the condensate side of things?

If on the steam it would thwart firing just as you were getting close You know how that goes...

Also I assume your MBH as you use it means "million" BTU's per hour. Makes sense given the magnitude of your numbers. At first I thought you meant the traditional M as in "thousand" so jumped at "all of that piping and very little boiler"...


So what is the outcome of radiator EDR measurement versus the boiler output? I agree much lies within that number unless I missed it from another posting.

chip_10

Thanks For The Reply Brad,

The Steam Established Sensor is on the Condensate Return Line Returning from the last building so like you said it will not make the boiler short cycle.
And Yes the "M" is Million BTU per hr.
And I have not yet tried to figure the EDR numbers for myself yet but am going to attempt it this weekend. The Consultants handled that and I was not privy to this info at this point but I do have an excel sheet with all of the necessary data to do the calculations but I personally have not had to try and run these numbers before. From what I've been told it's sized correctly but I am only going to take that at face value as they may just be blowing smoke.
Any more info you need just ask.

I will repost again on Monday with the results of the EDR calculations.

Good Weekend All.

Chip

ttekushan_3

Ok. Here we go.

According to my thumbnail calculations, you need a 95 HP boiler for that space. Which ironically is your 70HP boiler plus the pickup factor required to preheat, purge and "prime" the system for proper heat distribution.

Your old boiler (given the input rating and high-fire efficiency) was 150HP. The L.E.S. (nice boiler, BTW) is 70HP.
Can you be assured that the old boiler didn't START the cycle at high fire, and then drop to low fire once the the pick-up load was satisfied?

70HP is about right for steady-state full operation at 70F room temps, but there's NO pickup factor there.

You need to park a L.E.S. HF3-20 next to it to handle the pick-up load. Put the HF3-70 to its optimal settings. Then the HF3-20 can power down after the pickup load is handled.

The good news is, THIS IS THE MOST EFFICIENT MEANS OF OPERATING STEAM BOILER SYSTEMS-- A smaller boiler for pick-up load only. Ironically, the fuel consumption will drop sharply once you do this.

-T

When I have time I'll show you how I came up with this.

FRANK_24

HOW 'BOUT THIS??

Now I'm no mastermind, nor do I have any majicall letters after my name, BUT I was wondering..............hmmmmmmmmmmm what about the heating surfaces of the boilers? If'n the old one was rated at twice as much as the new, the heating surface was twice as big? No?? The amount of fuel you throw into one of these boilers can change the rating, but not the heating surface. Off the top of my mind, the boiler is too small. NEVER do steam boilers run constantly to provide pressure. I've installed too many monsters to think other wise. Steamers are supposed to produce pressure in the entire system during one cycle [that shouldn't last all day]. You are probably running out of water during the cycle. Yes? Hmmmmmmmmmmmm too small.

ttekushan_3

calc scribbles

Don't forget we're concerned about actual EDR. I estimated base on typical radiator sizing techniques of the era.

Glenn Sossin_2

Thermostat

I had a situation like this in a series of 3 separate buildings with 12 coops each. @ buildings got new boilers - boards idea. Called into consult. Found a whole host of issues when I looked inside the apartments. Bad vents, radiators pitched wrong, steel fin baseboard mixed in, furniture placement, added skylights to top floor unit, etc.

The main factor - the thermostat, where it was located and the new tennant that controlled it.

Could that be the cause - all other things being equal of course ??

chip_10

Thanks Again For All THe Help All,
Here is what I have come up with over the weekend on these EDR calculations.
I think I have figured the EDR for the radiators only but I do not know what else I should figure in for the piping since there is 7 buildings with 2 livable floors with the basement rise and all the tunnel piping.......
If anyone wants to look over my figures and see if they are correct I could only thank you too much!!!!!
Or shoot me an email and I will send them to you in Excel Format for Easy editing.

BTW:FRANKIEWRENCH
I agree with you about the overall heating surface of the boiler decreasing in size too much. Since the vessel and tube sizes changed so drastically along with the change in the output nozzel size greatly reduces the volume that can be output in a specific amount of time. With this boiler we are not running out of water since the overflow tank more than makes up for it but the water being put back in is always between 140 degrees and 165 degrees. So that probably has some effect on steam output but it's being pumped in to the rear input through the equalizer line so it has time to come up to temp quick enough not to cause shock.

Also thanks ttekushan for the scribble! Maybe this info is what you need to verify the calculations on your scribble which I thought was pretty Darn good considering what you knew at the time!!!!!

Thanks Again All for all the help.

Chip

Brad White_9

wdikijap?

"Now I'm no mastermind, nor do I have any majicall letters after my name, BUT..."

Those letters work for me, Frankie!

ttekushan_3

How did you arrive at those EDRs?

I'm a little confused looking over the spreadsheet and looking at the radiator dimensions as they correlate to standard sizing (albeit with a certain amount of latitude within basic configurations-- like the old fashioned rounded column, the squarish cast iron tube or the very squarish cast iron ultra thin tube radiators).

Compared to the general cross references I looked into with the dimensions you provide, the EDR (equivalent direct radiation) values I come up with are approximately 2.5 times what the spreadsheet says.

For example a 38"x 9" radiator should be around 6 square feet of TOTAL exterior cast iron surface area per section. This factor of approximately 2.5 appears consistent across all radiator sizes recorded.

So the 3884.95 (which I will take the liberty of rounding up to 3885) times roughly 2.5 = 9712.5 which I will round to 9700 square feet of EDR.

(9700 s.f.)x(240 btu/s.f.)= 2,328,000 btu

Plus I=B=R pretty standard pick-up factor of 1.33 for piping etc:

(2,328,000 btu)x(1.33)= 3,096,240 btu, or 92.5 HP

Of course, the original piping is sized for the now missing radiators, so you could add a bit for for that; perhaps another 5-10%. But considering the size of the system, the I=B=R scale often calls for for slight reductions in the factor (like 1.25) I think these special considerations leave us in the area of 1.33 and leaving it at that.

So 95 HP total should do it. I stand by my original conclusions.

-Terry