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Loss of water with steam boiler.
Homeowner with a 300k BTU Utica steam boiler that I have successfully downfired to 240 k to match the attached load. Has worked very well since doing that 5 years ago. Starting last year and continuing this year I have noticed that the auto fill system was kicking on quite often. Today I monitored it for most of the day and found that based on the sight glass, it lost more than a gallon and a half of water in a bit more than 5 hours, which is quite excessive. I have checked for steam condensate at the chimney when running, but saw nothing. How could it be losing that much water without any sign at the chimney? Any ideas on what else to check for?
Leaking return piping? Do you have any underground returns? Many steam leaks throughout the system perhaps? Steam leaks aren't usually obvious.2014 Weil Mclain EG-40
EcoSteam ES-20 Advanced Boiler Control
Boiler pictures updated 2/21/150
Are there any buried wet returns under the floor that could be leaking? You may need to shut the boiler down and over-fill it up to the risers and see if you detect any water on the floor around the boiler. It is possible the boiler is leaking and the water is evaporating. Is there any indication of rust/leakage in the burner area?0
No underground piping. There is only a short section that is in a crawl space. I'll try to get a look into there. Should be able to see steam condensate in the cool area. There are few/no steam leaks throughout the system.
All wet returns are visible. No indication of rust/leakage in the burner area. Will try filling the boiler up to the risers and see if any water leakage shows up.
Thanks for the ideas. Will followup with my results.0
Well I followed the dry returns and wet returns as best I could and saw no evidence of leakage. Then I shut off the boiler and filled to the risers and a pretty good leak showed up. So much that I am surprised I saw no steam condensate from the chimney. Anyway, new boiler needed, obviously.
Now I would appreciate suggestions for a high efficiency steam boiler of about 200-210,000 BTU per hour capacity, or a regular efficiency boiler at about 240,000 BTU capacity.
Thanks for the help.0
Can you tell where the leak is? Is it actually in the boiler block?
Did you actually calculate the total EDR of all of your radiators? That's the first step in determining the right boiler size. When you total all of the Radiator EDR, you match that number to the sq. ft. of steam output by the boiler (listed on the boiler plate). The closer the match the better.0
There's only so much efficiency to be had from a boiler running at the return temps seen in a (non-vacuum) steam system. A wet-base boiler with a power burner will maximize your thermal efficiency and also gives you the option of two stage firing or even full burner modulation. A boiler having a three-pass design (as opposed to a pinner) should add another couple of percentage points of efficiency. What are your fuel costs like? If you're using oil you'll get this anyway. With LPG it might make economic sense. If you have NG service, it probably won't make sense on a pure economic level at this time.mel rowe said:
suggestions for a high efficiency steam boiler of about 200-210,000 BTU per hour capacity, or a regular efficiency boiler at about 240,000 BTU capacity.0
All I know is that when I filled the boiler with water up to the risers, water started dripping down into the burner area. When originally installed 25 years ago, I had no idea about how to calculate the load, etc. Only after finding this site and buying the book and doing a lot of reading, I calculated the everything and confirmed that my 300,000 BTU boiler was too much and the steam velocity was over 80 ft/sec. I revised the near boiler piping myself and added a second 2 in. riser and a 3 inch manifold. Then with the help of a heating tech. we took out 4 of 16 burners and adjusted the boiler. After that it worked so well that I hardly knew it was there anymore. It has handled weather down to minus 9 degrees and only ran 97 % of the time, so 225,000 BTU seems about right for a new boiler.
We're on NG, so "A wet-base boiler with a power burner will maximize your thermal efficiency and also gives you the option of two stage firing or even full burner modulation." sounds interesting. What brands would you recommend?
Good on you for making those piping changes long ago!
Now it seems to be time to replace the boiler, as a result of your overfilling test.
You must measure the EDR of all the radiators to choose a new boiler. I know that your down-firing has worked, but you may need even less capacity in the replacement.
You may be surprised how much lower the replacement boiler can go in BTU.--NBC0
I went through those calculations years ago. That is what gave me confidence to reduce the capacity. From those calculations and my experience in extremely cold weather, I am very confident that a boiler in the 220- 225,000 range would be great, especially if I can get some recommendations for a boiler with a wet-base and two stage firing. Any brands you would suggest?0
Wet-base boilers (commonly marketed as oil boilers) are available from quite a few manufacturers -- many of whom currently do not approve of pairing them with a gas power burner. Slant/Fin seems to be OK with doing so on their Intrepid. They make a good boiler and their support draws high marks from a number of participants here.
I'm not an expert on gas guns, but the Powerflame X4M-400 is about the right size and modulates from 100 - 400 MBH. There's also a high turndown version that I believe will go all the way down to 40 MBH. The Midco LNB-250 would be another option to consider. Full modulation is going to require an external pressure control of some sort -- either a generic PI/PID box, a PLC, or DDC. Converter boxes are available which will translate two-stage or three-stage inputs to 0-10V setpoints.0
Thanks very much for the info.0
Is your btu input or output?It's much easier to compare boilers with the edr measurement as it takes efficiency out the the equation. It's really not that hard to measure. I have SF with gas conversion burners and love them.Two-pipe Trane vaporvacuum system; 1466 edr
Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF0
Using the Radiator EDR and comparing that to the Sq. Ft. of steam rating on the boiler also ensures the boiler has the manufacturer's recommended Pickup factor as well for heating/maintaining temps of all pipes/mains. Even if you don't want the full 30% pickup factor, at least know you need some. I wouldn't go less than 20%.0
I dug out my previous estimate for EDR and it was 612. So using a pickup factor of 25% that would require a boiler of close to 760 sq ft. of steam, which is the capacity of the boiler installed 25 years ago. The system never operated well and after reading "The Book" I added a second 2 in. riser and a 3 inch manifold. By my calculations the velocity of steam was still much too high and I constantly had plugged rad vents on my one pipe, parallel flow system. To reduce the velocity I considered down-firing but was discouraged from doing so based on the EDR I had calculated. I had done a lot to insulate the old house: new double glazed windows, 8 in. of spray foam in the attic, and insulation in the walls, so I just was not convinced that the pickup factor should be the same as without insulation.
In desperation I went ahead and took out 4 of 16 burners in the boiler and adjusted everything. After that I hardly knew I had a one-pipe steam system anymore. My wife had watched me spend so much time keeping the system working adequately in the past. Now she kidded me that I had nothing to keep me busy all winter. I also confirmed during an extremely cold period for us in Michigan, minus 9 degrees F, that the down-fired system (300,000 down to 225,000 BTU input) kept the house comfortably warm and still ran only 97 % of the time.
So, having read "The Book" I understand fully how to calculate EDR , and calculate the necessary capacity; however, if I followed that when deciding on a new boiler I would have been right back up to the 300,000 BTU input capacity. Yet I went with a 210,000 capacity boiler and I have no reservations about its ability to take care of our heating needs. My only reason for bothering you with all this is to point out that there should be something to account for changes in heating load from the time the house was originally built, with poor insulation and excess radiator capacity. Clearly the house now only needs about 200,000 - 210,000 BTU boiler capacity, yet by the EDR calculations I would end up with much more (excess) capacity.There is no place that I can eliminate radiators, and it would not make sense to try and reduce the size just to reduce EDR, so it seems to me that calculating capacity should take into account the current amount of insulation of a house and if well insulated perhaps the pickup factor should be zero.
I say that because even though my EDR is 612, the new boiler is rated at 533, and I expect no problem, even in coldest weather. So, maybe the boiler will not ever 100% heat every section of every radiator, but so what, if it heats them enough to put out the heat necessary to keep us comfortable? I understand that from a heating contractor's perspective, it is best to always err on the side of caution and go with the higher capacity, because you never want to hear from an irate homeowner with a cold house.
On the other hand maybe it might be of use in making sure your quote on a new boiler is better than your competitors because you can confidently quote a lower capacity boiler. Anyway, I have greatly appreciated the info and help I have gotten from experts here, so I just thought that the guys that have to quote and install and stand behind new boiler installations might find these thoughts interesting.
don't add 25%. pickup factor is already included in the EDR rating of the boiler.mel rowe said:
I dug out my previous estimate for EDR and it was 612. So using a pickup factor of 25% that would require a boiler of close to 760 sq ft. of steam, which is the capacity of the boiler installed 25 years ago.
If your mains are well insulated, you may be able to get away with a boiler with a lower EDR rating than the attached load.
What boiler did you get?All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Thanks Abracadabra, for clearing that up. So my 612 EDR multiplied by 240 gives me 146,880 BTU. Then with 82% efficiency, that becomes 179,100 required. So with a new boiler rated at 207,000 gross, that means I have a 12% pickup factor. Since the old boiler at 225,000 gross BTU ran most of the time when it got down to minus 9 a few years back, I'm not sure i would want to go much lower in capacity.
As for the new boiler, I intended to get a Burnham, but when it was delivered it was a New Yorker. I quickly checked out all the info I could find and determined that it was made by a sister company of Burnham and that the cast iron heating sections were the same, along with most of the controls. Rather than delay everything by insisting on Burnham, I decided to go ahead and install.0
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