Boiler Runs a LOT

Jeremy_10

I noticed that my Burmham steam boiler cycles a lot. It runs for 10 minutes or so then shuts down. After only less that 2 minutes it is back on again for another 10 minutes or so.
The pressuretrol is set Main=2, Diff=1.75 Diff is subtractive.
I am having a service person come look at it however, I would like some idea of what might cause that to happen.

Oh yes, the stat is in a protected room without drafts etc., but the stat is old.
Could this be caused by a plugged pigtail?

Thanks

bruhl

burnerman_2

may have a crack

if it is old it may have a crack and allowing steam to release and then add cold water that needs heated if the room is up to temp it should not be running so it must be losing heat somewhere royboy

Jeremy_10

Thanks for the input. The boiler is only 6 years old. I hope it doesn't have a crack because I consider it "new".
I wish I had a water meter on the feed line, but I don't
bruhl

Jeremy_10

Burnerman

Another thought, the humidity level in the cellar is approx. 50 and the dehumidifier doesn't even have to run this time of year. Might that indicate no steam loss?
Also, I did feel the top jacket around the vent area, and it did feel quite hot. Is that normal?
Thanks again.
bruhl

Daniel_3

That is all normal.

Few questions:

1.) Do you have an indirect coil for your Hot water heater?

2.) Does the water look clean through the boiler gauge glass?

3.) How long has the short cycling been happening?

4.) What is the steam sqft. on the side of the boiler rating sticker and what is the sqft. edr of all the radiators in your home? What kind of radiators? Free standing? Convectors? Baseboard?

5.) Can you get some quality pictures of the near boiler piping and post them in this thread?

6.) Do you have main vents at the end of your steam mains?

7.) Are any vents on your radiators or the ones that may exist on your mains leaking steam when the boiler is firing?

8.) Did you have any service done recently to the boiler?

This is just a primer.
Daniel

Jeremy_10

A Few Questions

Hi Daniel, I have some info, and at a loss for other answers.
1- indirect coil for HW? Yes, the HW comes from the boiler. I am in the process of taking Brad Whites advise and getting some well insulated storage for water.
2-water clean? yes, I would say so. Service person thought so.
3-How long? Don't know for sure. Two weeks ago I would have thought it normal. You know, before Dan H book.
4-Steam sq ft on boiler sticker? 396 sq ft,
sq ft EDR? Don't know, but boiler was sized by measuring rads.
Kind of rads? Old free standing cast iron. Newest probably 50 years old.
5-Pictures? I'll try.
6-Main vents? Yes on longest [28ft]main, new Gorton #1 shorter main goes to risers real quick so nothing there. Rad vents have to do that.
7-Vents leaking? No I don't believe so.
8-Recent service/ Yes I had the annual "tune up" done a few weeks ago. I called today and asked for a steam man to look at it.
Now for the pictures.
bruhl

scrook_2

Normal

It's because the boiler can produce steam slightly faster than the radiators connected to it can condense it, so the steam pressure rises to the cutout, the burner stops, condensation in the radiators causes the pressure to rapidly drop to the cutin and burner restarts, the cycle repeats until the thermostat is satisfied.

The next smaller size boiler -- about 30% lower input & output -- might have been slightly too small, so it would never cycle but not all the radiators would heat fully either.

I'd guess it cycles less when hot water is being demanded from the tankless coil (say for showers) while the thermostat is also calling for heat though.

Jeremy_10

scrook, thanks for your input. That was a lot of stuff for you to read and digest. I appreciate your taking the time to do that and of course for your reply.
bruhl

mike in pa

header?

Maybe i am not looking at this right, but...are the two supply risers coming out of the boiler going in two seperate directions? If so, you should have a common header for both risers to feed into..preferably larger than 2" pipe.

Just might help with steam distribution.

Jeremy_10

Mike in PA, this is actually Mike in MA, yes I believe that you are seeing it correctly. There is no long header,serving the two mains, just two smaller ones going in different directions. This system piping was originally for coal, then converted to oil with the original boiler, and then replaced with the Burnham that is there now.
This was the house I grew up in so I remember some of the history from years ago. Six years ago [hell six weeks ago] I didn't know anything about this stuff. The installer was faced with blending the old with the new, and obviously, I don't know enough now to say whether it was done correctly. In fairness, my dad would have gotten more than one quote, so the installer also had to be competitive with others. Money is still an issue, but I would look at it differently today.

bruhl

Jeremy_10

Mike in PA, sorry but I appreciate your input. I neglected to say so in the earlier post.
Do you think that this two riser/mains going in different directions situation is worth getting changed? I imagine that could run into serious dollars.
bruhl

Jeremy_10

Might this be a clogged pigtail issue?

mike from pa.

header

I would chnage the piping to look like the diagrams in the instructions. Check out www.burnham.com. An excelent source for data. click on the pv boiler and then I O literature

The near boiler piping is crucial for steam boiler installs.

Jeremy_10

Thanks again Mike

bruhl

Jamie Hall

Cheer up

I have a Weil-McClain industrial -- much bigger system -- and it does the same sort of thing. I'd say it was normal. You have to have enough burner/steam production capacity to handle the pickup load at the beginning of a cycle. Then she'll run for a while, until almost all the radiators are hot. What happens then is the traps close (assuming vapour here!) and pressure builds. Burner shuts down. Steam condenses, pressure drops -- fast. Burner fires up until radiators are full of steam again and traps close. Pressure drops. And so on. Probably is much more noticeable if you are recovering from a set back temperature than if you are just maintaing space temperature.

The only cure for it is a modulating burner... which are (to put it mildly) uncommon and can also be a real pain.

Jerry_23

Quick cycling

I have a similar situation with a steam boiler. Cutoff is set at 1.5 pounds, cut in is at 1/2 pound. Several original radiators were removed and a few were replaced with smaller units. I estimate that the EDR has been cut by 30% or so. The unit was probably oversized originally even before the reduction in radiators
Unit cycles on and off at about 2 mins on, 1 min off after reaching steam temp. No leaks, vents on risers working. The boiler is just too large for the current load. I was thinking about de-rating the unit by plugging the feeds for two of the five flame tubes. Because of the layout of the ignighter, I would have to disable the outer two tubes of the five. Does anyone have experience with this approach?

Thanks and happy holidays

Daniel_3

I doubt the pigtail is clogged as the boiler is fairly new, just a few years. Try setting your main to 1.5 and your diff to .5 leaving the pressure change a little more than the .25 that exists now. You might want your cycle to ride a larger pressure wave than what exists according to your setting. What type of rad vents do you have and how many different brands or are they all the same? Concerning your tankless coil. I have a friend who has an oil fired unit with the same set-up that cycles often. I think this is due to the hot water call to an extent. I had found a main vent that was surely busted and after replacing that it helped greatly by lengthening the short cycles. Your on the right track to fixing this issue though. I can only add .000002 cents.

Jeremy_10

Hi Daniel, thanks for the information. I'll change the pressuretrol settings as you suggest. I thought perhaps the settings were a little to close together, but what do I know.
The main vent is a Gorton #1. That is new and replaced a Vent-Rite #77, if I remember correctly.
The rad vents are Vent Rite #1, which I believe is a discontinued item. They have the little wheel that allows different settings depending on need. They are at least 6 years old.
In any event, I have a full set of new Gorton's set to replace them. I sized the new Gorton's per the Gorton sizing suggestions. The new Gortons will be in place within the week.
Thanks again for your .000002 cents Daniel.
bruhl

mel rowe

Jerry, I'm assuming you have a one pipe system. You didn't mention how many of these on/off cycles were occurring. One of two at the end of the overall cycle would not be considered excessive, in my opinion. However, consider this as a goal -- if all the rad valves were sized or adjusted so that all rads heated and shut off at about the same time that the stat set temp. was achieved, then the system would shut down, with no rise in pressure enough to start the cycling. I have achieved this on my system, although I have to admit that I took an easier approach by installing a lot of TRV,s inplace of regular rad vents. By the way I also have a boiler that is significantly oversized. It only has to run about 35 % of the time, even on the coldest days. I helped offset this problem by downfiring the boiler by adjusting the gas valve to allow lower gas flow. FWIW

Jerry_24

Boiler cycling response

yes, it is a one pipe system . The radiators all heat up within 3 minutes of each other. The system can cycle for 10 or more minutes once it has made steam depending on the current ambient and the required target. You have an interesting idea about the gas flow. I will have to look at the electric gasvalve. I don't remeber any 'user' adjustments adjustments

john_171

Short Cycling

> I noticed that my Burmham steam boiler cycles a

> lot. It runs for 10 minutes or so then shuts

> down. After only less that 2 minutes it is back

> on again for another 10 minutes or so. The

> pressuretrol is set Main=2, Diff=1.75 Diff is

> subtractive. I am having a service person come

> look at it however, I would like some idea of

> what might cause that to happen.

>

> Oh yes, the

> stat is in a protected room without drafts etc.,

> but the stat is old. Could this be caused by a

> plugged pigtail?

>

> Thanks

>

> bruhl



This is just a thought that happened to come to mind, but next time your burner comes on, note your thermostat setting. Then, note it again when it shuts off. If your rads have not heated much, or at all, and the stat is still not satisfied, it's possible that the heat anticipator setting could be off, if your stat is so equipped. This can result in short cycling, and really waste a lot of fuel. If that's your problem, remove the cover on your stat, and locate the adjusting lever (on the bottom, if it's a Honeywell) and move it JUST SLIGHTLY to the left. You'll notice an arrow, and the word "Longer" stamped there. Just an idea.
Also, you should definitely get your I & O Manual out and see the manufacturer's recommendations for the near boiler piping. It is CRUCIAL that your boiler be piped exactly as they show. The money you spend on having a pro fix this situation will result in much drier steam, and your system operating much more efficiently.

john_171

Short Cycling

This is just a thought that happened to come to mind, but next time your burner comes on, note your thermostat setting. Then, note it again when it shuts off. If your rads have not heated much, or at all, and the stat is still not satisfied, it's possible that the heat anticipator setting could be off, if your stat is so equipped. This can result in short cycling, and really waste a lot of fuel. If that's your problem, remove the cover on your stat, and locate the adjusting lever (on the bottom, if it's a Honeywell) and move it JUST SLIGHTLY to the left. You'll notice an arrow, and the word "Longer" stamped there. Just an idea.
Also, you should definitely get your I & O Manual out and see the manufacturer's recommendations for the near boiler piping. It is CRUCIAL that your boiler be piped exactly as they show. The money you spend on having a pro fix this situation will result in much drier steam, and your system operating much more efficiently.

bruhl

Thanks John. I'll talk to the heating folks and make them aware that I would like the near boiler piping changed to the manufacturers specs as shown in the I & O manual. I only wish that I had known that originally. But I hadn't discovered "the wall" at that time.
Have a great day John and all.

bruhl