First time poster with boiler that's been holding water as long the Hoover Dam. Pics and Vid

Dante_2

Photo Album: https://goo.gl/photos/4pycTnc1ytznWXeb7

My house was built in 1935 and has the original boiler which now runs on natural gas. It’s been keeping the house warm for the ten years that I’ve been here with no problems, until this month when I first fired it up for the season. The burner would only light about 50% of the time. The gas valve on the Honeywell Powerpile would open if I jumped the controls out. The open voltage on the thermopile was 550 mV. I replaced the thermopile first hoping that would be enough. It worked about 80% of the time so I retested and the pull-in was high so I put in a new Powerpile VS820A1054. I clocked the meter and read 142,000 Btuh. The plate on the burner reads “45,000 MIN. INPUT B.T.U PER HOUR” and “300,000 MAX. INPUT B.T.U. PER HOUR” My main concern is that the flame is partially yellow and that I don’t know what the input should be. Adjusting the air door would not get rid of the yellow flame. There is a video in the album. I’m probably going to call a pro to check it out and do a combustion analysis, but I was wondering if anyone had any recommendations and is it ok to use it til after Thanksgiving.

I put a few pictures in the album of the boiler and piping in case anyone would like to comment. I read We Got Steam Heat! and spent several hours reading on this site. I read about how the Pressuretrol is notoriously inaccurate and how knuckleheads try to solve problems by boosting up the pressure. My system has always worked like this: the thermostat tells the boiler to fire and it keeps going until the thermostat is happy. From what I’ve read from Dan Holohan’s writing, I got the impression that the Pressuretrol is what determines the pressure in the system. So, I checked my system which was about 7 PSI. I adjusted the differential all the way down, but it was still too high. There is a small tab of metal that actuates the switch in the Pressuretrol. I bent it up slightly so it would cut-out at a lower pressure. I thought it would take several adjustments to get it right, but the first time I fired it up it cut out at exactly 1.5 and cut in at .5. I watched it do this cycle several times with precisely the same results. I thought I hit the lottery. So then I was wondering how long each cycle should be and how many cycles should it take to satisfy the thermostat. That research led me back to this site, where to my dismay, there is some disagreement even among the pros. Please correct me if I am wrong, but I now think the pressure controller is more of a backup device, kind of like the pressure relief valve, and the pressure should really be a function of the venting and the rate at which the system produces condensate. Now my system cycles on pressure. I removed the vents on the mains. They were on the elbows right above the vertical pipe that returns to the bottom of the boiler. I’m not sure what kind they were (is China a brand?) I put 45s, 10” nipples, wye strainers, and Barnes and Jones Big Mouths on each one. This only shaved 4 minutes off the time it took to get heat at the radiators from a cold start. I was surprised because I cut open the old vents and measured the vent hole at about 1/32” diameter. What is my next step? This is getting too long so I’ll stop here, but I have many more questions. Thanks

MilanD

@Dante whenever there is an issue with burner not coming on or staying on, replace thermpile. If that didn't do it, replace the gas valve. From what you are describing, and from looking at your photos, that gas valve is one old piece. Next time it doesn't come on, tap on it with the handle of your screwdriver. If you hear it click and then the fire comes on, it's stuck and you need a new one. Easy to replace.

Btw, congrats on your original boiler. Wow. Keep the pressure low and check your rad vents too and replace as needed. Some rad vents models can be fairly inexpensive and are easy to replace. Small orifice vents on rads closer to the boiler, larger orifices on ones that are farther away. You should be able to run it at 6 oz (1/2 psi) if all is well balanced.

Also, make sure to blow it down weekly.

MilanD

As to flame adjusting, if I'm not wrong, the 2 saucer-looking discs, coming out of the gas valve, are adjustable. The distance between them will regulate the flame. Play with it to get the desired.

adambnyc

Just curious (learning) why would a steam boiler require an aquastat if there is no hw loop on it?

nicholas bonham-carter

The pressuretrol is only an upper limit pressure control device. A vaporstat and 3 psi gauge would be better able to fine tune the system. My attempts to modify/adjust a pressuretrol for lower settings, never worked, and so I switched.
The intermittent gas valve operation could also be the result of bad connections elsewhere in the thermostat, LWCO, pressure trol, etc, so check them out.
What diameter are the pipes connecting the big mouth vents to the dry returns? If those are too small, the main vents will not be able to operate at their maximum capacity. Maybe your system is large enough to need still more main venting.
My recommendation is to start with small radiator vents (Hoffman 40's), , and large main vents. You want the pipes to fill with steam first, before any radiators begin to fill, and that will enable all the radiators to fill simultaneously, giving a balanced system. On top floor radiators, larger vents may be needed to allow a tall column of air to escape more quickly. Distance of the radiator from the steam supply pipe is the factor here.--NBC

Dante_2

@MilanD Thanks for the comments. I probably wasn't clear in my original post and some of the pics were old. I did replace the gas valve and it works perfectly now as far as turning on the burner. Those discs are adjustable, but I measured carefully and put the way it was when I replaced them. I will adjust and see if it helps.

@adambnyc I have no idea why that Aquastat was there. I see no evidence of there ever being a hot water loop.

@nicholas bonham-carter
I installed a 0-3 psi gauge next to the old one. The smallest pipe feeding the main vents is 1/2". My system does heat evenly, with the exception of the baseboard that was added later. I have Maid o Mist D vents on the two rads upstairs and they work well. Most of the others are a mix of home store Chinese ones.

My house is small (1300 sq ft) and I'm wondering if the oversized burner is causing the cycling on pressure. If the mains fill quickly but the rads too slowly could that cause the high pressure?

Also, from that video, how does that flame look? Too little air?

Thanks

MilanD

@Dante - I would leave plenty of air in there for the fire. This damper worked for coal. Now, you want plenty of draft so it doesn't back draft. I'd leave it open as wide as you can and make sure it's drafting properly.

As to the flame, it could be different volume of gas coming out with the new valve. Readjust those discs to get the desired. I think it should be blue light with yellow tips. If you are getting it, you are fine (your video doesn't want to open on my computer). If it's all yellow (and loud), you are too much air from the discs, and if you are all blue (and quiet), it's too small. Disc regulate fuel/air mixture and the height of the flame, and the old flue makes sure there is enough oxygen there to make the flame and push the exhaust to the chimney.

I manage 5 different buildings as my "other" occupation. 9 burned air furnaces of various age, one hot water boiler and one steam boiler. One of my burned-air furnaces is an old old... 40 years old furnace (I forget the name). It has this exact burner set-up with the discs. When I replaced the gas valve on it, it took me a while to figure out the correct distance again. Luckily there was another one furnace like it, so I fired it up and matched the flame. That's where the yellow/blue balance comes from. You want the fire to 'hug' your bottom off the boiler, no more, no less.

And one last note: as you probably know from reading Dan's book, if you are having the boiler run on over 1/2 psi, you are throwing money away. Everything should be just fine on 6 oz. of pressure. To check, fire the system from 0, and run to the basement and see what the pressure is when the last and farthest radiator gets hot. You have that nice low-pressure gauge now. If the system is balanced, this will be at 6 oz. At that point you want to have the burners shut off, wait for the pressure to go back down to 0, or 0.1, whatever, and then start cooking the steam again. Short cycling is fine. Thermostat will be calling until it is satisfied, as it should, and the boiler will only make as much steam as it can before it over-pressurizes the system.

I would strongly recommend you get the vaporstat. It will make your life easier, with less pressure, and your wallet fatter. Supplyhouse.com has them as do local mechanical supply shops.

That's one nice rig there.

Steamhead

That old snowman is probably about 40% efficient on gas (or oil). It doesn't have a whole lot of heat-transfer surface, which would result in high stack temperatures. Time for a new one.

Chris_L

I can't speak to the flame or the boiler itself, but as for the gas valve, the old one in the picture looks to be in the "pilot" rather than the "on" position. I assume (hope) you've got the new one in the on position.

Also, it doesn't look like you've got an auxiliary pressure limit on that boiler. At least here in MA (if not the whole US), code calls for a secondary pressure cut-out on gas millivolt systems. If tripped, it shuts the boiler down completely and requires re-lighting the pilot.

So if you do keep the boiler and get a vaporstat, you can use use your pressuretrol as the auxiliary limit.

Fred

Have you ever taken the Pigtail under the Pressuretrol off and cleaned the inside of the pigtail and the opening into the LWCO (MM#67) that the pigtail is mounted on? Mounting the Pigtail/Pressuretrol on the #67 is really problematic as it relates to the pigtail filling with gunk and either allowing the pressure in the system to get way above what you want it to be OR, Pressure gets trapped on the Pressuretrol side of the pigtail between a clog and the Pressuretrol, preventing the Pressuretol from dropping to Cut-Out pressure so the boiler burner can kick on. I'd typically suggest moving the Pressuretrol to a different tapping on the boiler but I know on older boilers, you are limited on options. If you can't get it off of the #67, just try to clean out the pigtail at least once a heating season, preferably twice.

Dante_2

I screwed open that baffle in front of the venturi to get more primary air. The flame is now almost completely blue with occasional wisps of yellow. If I open the secondary air door the flame gets very sloppy and almost completely yellow. I adjusted it in small increments and it seems best right where it was.

Here is where I stand so far. With the boiler completely cold and the house temp at 63°
Minute 0 I turned the thermostat to 68°
Minute 21 the main vents closed
Minute 24 all radiators start to get warm, pressure gauge is barely bouncing off the zero
Minute 30 most radiators are about half way warm, pressure at .2 PSI
Minute 40 all radiators completely warm, but the two largest just barely at the ends, I think these need much bigger vents, pressure is 1.25
Minute 50 house is 67° and pressure hits 1.5 and cuts out, at this point it cycles repeatedly trying to hit those last couple degrees. Once it cuts in it takes 3.5 minutes to cut out again.

On most winter days my thermostat calls once at 6am and then it's good until the next morning, but by then it could be as cold as 59° in the house. Maybe I might save energy if I had it cycle more.

Dante_2

@Steamhead I know it is inefficient, but I'd like to know how to calculate what my natural gas usage would be with a new boiler. If my 40% efficient boiler is replaced with a 80% one does that mean my usage will be half? My heating bill for the last two years averaged $990/year. In Rhode Island that's not really that bad. When I consider the cost of having the asbestos removed, and then the boiler replaced, the additional maintenance and repairs, and the life expectancy of that new boiler the ROI doesn't seem very good. Right now I have a boiler that, until this month, I haven't spent a penny on in the ten years I've owned it. The Powerpile gas valve is probably the most expensive part on it and it's new. A couple years ago a blizzard knocked out our electric for 3 days. The city was moving elderly people to the high school and community center to stay warm. My mother and grandmother stayed at my house because it doesn't need electricity for heat. Even if a new boiler ran on nothing but air I would still have at least 7 years to break even.

Fred

What kind of thermostat are you using that lets the temp drop from 68 to 59 before it calls for heat? Are you bringing the house up to 68 and then turning the thermostat off or all the way down? We typically suggest set-backs be kept at 2 to 4 degrees to avoid having the boiler run so long that it starts to short cycle. From your numbers, it looks like you start to short cycle at about a 4 degree recovery. How long does it take for the main vents to close from the time your boiler header is hot? It is important to understand that number to determine if your main venting is reasonable. It took 50 minutes to get those 4 degrees. Part of that time is getting the water to boil and make steam, part of that time is getting the near boiler piping up to temp and then the rest of the time helps to determine if your main venting is reasonable. Every minute you can cut from the time it takes to get from a hot header to closing the main vents is an extra minute you have to heat your home. How long are your mains and what size pipe? Focus on main venting first as that may to be the low hanging fruit. Typically it should take between 5 and 7 minutes to fill the mains and close the Main vents, after the header is hot. One Big mouth on each main may not be enough, depending on the length and size of each main.

Dante_2

@Chris_L No, it does not have any control that turns off the pilot. I don't even know how that could be done. The only way to turn off the pilot is to blow it out, turn the valve by hand, or turn off the gas. I'll look in to that more.

@Fred I have never removed the pigtail and cleaned it, Right now the cut in and cut out are very consistent. Could I mount it to the side where that Aquastat was?

It's a Lux programmable. I have it set at 68° from 6am-8pm and 63° from 8pm-6am, but with 3.5° hysteresis. So it actually goes to almost 72 in the morning. It never short cycled before because the Pressuretrol was set so high. It just ran til it hit the temp. (I'm starting to feel like a knucklehead) Now that I'm understanding how this system works I realize my programming is idiotic. What do you suggest? I can set 4 temp changes per day. You're right about the 4 degree recovery short cycling. As for the pipe questions I'll go measure and get back with those. I don't think my boiler has a header. It's just two main pipes that come out the top and each forms a loop and drops back down from where it started.

Fred

@Dante , Yes you can mount the Pressuretrol where that Aquastat is currently mounted, just be sure the Pressuretrol itself is above the water line. There should be an adjustment on that thermostat to tighten up the temp range. 3.5 degrees is crazy. If there isn't, I'd get a different thermostat. Honeywell makes several programmable tstats that are compatable with steam. Just make sure it can be programmed for "1" and"2" cycles per hour. As a matter of fact, you should check the programming on that Lux and see what the cycle program is set at. Virtually all thermostats come shipped from the factory programmed for "5" cycles per hour, standard for forced air.
Worst case, if you feel you must have a set back grater than about 3 or 4 degrees, program it so that you recover 2 or 3 degrees at say 4:00AM and then another 2 or 3 degrees at say 6:00AM. That way the boiler can recover(run), in increments.
Measure those pipes, length and diameter and let's see if you have enough venting. Typically returns don't need to be vented but In your case, because the vents are at the end of the returns, you will need to include the length of the returns in your measurement because that air will need to be evacuated as well before the vents close and the steam will start to move into the radiator run-outs.

Dante_2

@Fred The boiler was still a little warm when I did this test. I stuck a temp probe on the main pipe about 8" up from the top of the boiler it was 125°.

After 14 minutes I started to feel warmth at the main right after the elbow; the temp probe read 183°. The right main closed 4 minutes later and the left about 20 seconds after that.

The right main is 34' long and the left is 36' long, but those measurements are to the point where it loops and changes to 1" pipe. So the length from the boiler to the main vents is about 75' for each main. The mains are 1 1/2", the risers 1 1/4", and the return 1".

So I estimate that the amount of air that must be vented from each main is about 0.73 cu. ft. If the Big Mouth can flow 2 cfm at 1 ounce I think they should be more than adequate, but I don't know if that's the proper way to calculate it.

Fred

@Dante Based on your info, it seems like the Main venting is good and that steam is reaching your vents in about 4 minutes after the boiler makes steam. Fourteen minutes for the boiler to start to make steam seems like a long time but as Steamhead said earlier, that old boiler doesn't have a lot of heat transfer surface. Check your thermostat and make sure it is set for 1 or 2 cycles per hour (2 might be best, in your case as the boiler will remain warmer and take less time to bring water to a boil). Also try to rethink your setbacks.