Joined on November 14, 2009
Last Post on December 8, 2013
@ April 21, 2013 9:11 PM in EZ-Gas Stays, Boiler is Upgradeda lot like my Utica. Can't imagine why. :)
Is that a CycleGard or a SafeGard LWCO?
@ April 21, 2013 6:57 PM in A Steam Odyssey (Part 2): Midco Low-NOx Burnerwith the oil burner were between 465 and 500 degF. Note that my thermocouple is in the flue pipe about 30" from the boiler. Combustion analyzers probes are inserted much closer to the boiler and read higher temps..
@ April 21, 2013 6:52 PM in A Steam Odyssey (Part 2): Midco Low-NOx Burneris right up against the Kaowool liner in the firebox.
@ April 21, 2013 8:32 AM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerOvernight temperatures were in the 30's so I got to see the burner perform under real world conditions. Here are the statistics for two runs this morning. The Preheat cycle is the time it takes to heat the mains and see steam at the condensate sensor on the farthest radiator.
Preheat: 8:42 / 35.0 MBtu
Heat On: 31:13 / 122.4 MBtu
Total Cycle: 39:55 / 157.4 MBtu
Preheat: 7:42 / 31 MBtu
Heat On: 19:49 / 75.4 MBtu
Total Cycle: 27:31 / 106.4 MBtu
Preheat: 16:24 / 66.6 MBtu
Heat On: 51:02 / 197.8 MBtu
Total: 1:07:26 / 264.4 MBtu
The Beckett oil burner was rated at 245 MBH. For the same total time, that's 273.6 MBtu. There's not enough data yet to tell if the difference is significant.
I've attached a plot of the two runs. I need to spend some more time tuning the pressure controller to eliminate the oscillation when the pressure first comes up.
@ April 20, 2013 9:29 PM in A Steam Odyssey (Part 2): Midco Low-NOx Burnerand my system is designed for flexibility and experimentation. No way you'd put that in the average home.
But it doesn't have to be that complicated. To set up a basic pressure control scheme, all you'd need is a pressure transmitter and a single loop controller with a 2-10 vdc output, both of which are readily available. The call-for-heat can be a wall thermostat, a Tekmar or other outdoor reset control, or even a Nest thermostat (if their adaptive algorithms for steam actually work). This all assumes that any problems with the steam system itself, main venting and the like, have been corrected. Otherwise a modulating burner probably won't help. As Mr. Scott once said, "I canna change the laws of physics!"
@ April 20, 2013 7:40 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerThe radial burner is a tube about 20" long and 3" in diameter. It's covered in some sort of fuzzy metal mesh which I think showed up better in the high fire video. The centrifugal fan is bolted onto the end of the tube. Gas goes into the blower on the right side, and the fuel/air mixture is injected (?) into the radial burner.
Your post reminded me that I forgot to post a photo of the burner before it was installed. Here it is.
@ April 20, 2013 4:47 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion ProjectOf course it's all relative but yes, I'd consider 71 db to be pretty quiet for a running motor. You could hear the Beckett running on the first floor, and feel it too. Can't hear the Midco on the first floor at all, except for the 15 second purge cycle when the blower runs at high speed. In fact, when the Midco is at low fire it's hard to tell it's running even when you're standing right next to it.
@ April 20, 2013 4:33 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerAbout the same as when you were here, Joe. Neil from Midco brought his suitcase analyzer yesterday and spent a lot of time trying to dial it in. We get very good NOx numbers out of the burner, but stack temps are still running hot so efficiency suffers. Neil is taking the results back to his engineers to look over; we'll see what they come up with.
@ April 20, 2013 1:33 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerThat's right, between 225 and 230 MBH seems to be the sweet spot. I haven't finished tuning the pressure controller yet, but it seems to control pretty well seeing how the accuracy of the pressure transmitter is +/- 0.02 kPa. When the video was taken it was between 45 and 50 degrees outside and 70 degrees indoors. It will be interesting to see how it performs in colder weather.
@ April 20, 2013 1:20 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerI've made three videos of the burner and controls in operation. The first and second videos include a look through the viewport while the burner is operating.
In the first video, the Midco Low-NOx burner goes through its ignition cycle, then maintains low fire at about 120 MBH.
In the second video, the burner goes through its ignition cycle, then ramps up to high fire at about 275 MBH.
The third video is of the modulating control. Here I've already raised a head of steam and am modulating the burner to maintain 0.4 kPa (just under 1 ounce per square inch) steam pressure in the boiler.
Here are the links to the videos on YouTube:
Low Fire Test
High Fire Test
@ April 20, 2013 12:46 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerHi Larry, the solid state relay is driven by a 5 vdc output from the single board computer in my modulating control cabinet that manages the outdoor reset control, DHW (I have a tankless coil), and burner modulation. I also have the wall thermostat as backup; when the system is in "thermostat mode", the thermostat activates a 24 vdc relay that switches 5 vdc to the SSR.
@ April 20, 2013 12:08 PM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerHere are some details on the controls for the Midco burner.
A call for heat activates a solid-state relay that puts 120V power to the Midco burner cabinet. A Fenwal HSI (Hot Surface Ignition) control unit in the Midco cabinet handles the ignition and burner management functions. Once the Midco goes through its ignition sequence and low fire is confirmed, my controls take over, modulating the burner firing rate with a 2 to 10 vdc signal, with a minimum output of 100 MBH and a maximum of 500 MBH on the LNB-500 (the LNB-1000 model goes up to 1000 MBH). There's a software-adjustable high limit in my control system that restricts the modulating voltage it to the boiler's max Btu input rating, in this case 280 MBH or about 3 vdc. The modulating control has several modes of controlling the voltage to the burner:
Modulating Control with Override
The initial output voltage to the burner is set to the high limit value and begins modulating on pressure from there. Since the pressure at startup is zero, the output will stay at maximum until pressure builds. This should yield the quickest preheat time, and as pressure increases the control will cut back the voltage to maintain the steam pressure setpoint, in this case 0.4 kPa (about 1 oz/in2 or 0.06 psi) . If the stack temperature drops below its setpoint, it will override the pressure control and modulate based on stack temp. This is intended to keep the stack temperature high enough to prevent condensation. It will automatically switch back to the pressure signal when the stack temperature is above setpoint.
I set up this control anticipating the burner at low fire might have condensing issues with the stack temperature. So far though, stack temperatures have been high enough at low fire that the override may not even be necessary.
Modulating Control without Override
Works the same as Modulating With Override, except that the stack temperature is removed from the control strategy and the system controls exclusively on pressure.
In addition to the modulating output, there is a separate power supply that delivers a fixed voltage to the burner. This is intended to be used when the system is in "Thermostat" mode. In this mode, the system operates as if it were a single-stage non-modulating burner.
For testing and experimentation purposes, the modulating control can be put into "manual" and the output set anywhere between the low and high operating limits.
This is left over from my original single-stage oil burner controls and won't be used with the Midco burner.
@ April 20, 2013 10:16 AM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerHere are some pics of the modulating control cabinet and hardware.
The 12 volt supply powers the single-board computer and sensors.
The 24 volt supply powers the thermostat and vaporstat lockout circuits. The Midco burner has its own 24 volt power on board, but that's only active when the burner is on, so I needed a separate 24 volt supply for the t-stat and v-stat.
The 24 volt relays on the left side of the cabinet are for:
1) Vaporstat high-high pressure interval lockout timer relay,
2) Thermostat on/off (the computer's digital inputs are 5 vdc so need an isolation relay here),
3) Midco burner firing status,
4) Midco burner fault status.
Didn't really need the last two but I had the sockets and relays lying around and room in the cabinet, so I figured why not?
@ April 20, 2013 10:07 AM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerMore photos of the installed Midco burner
@ April 20, 2013 10:04 AM in A Steam Odyssey (Part 2): Midco Low-NOx BurnerThe first Odyssey thread was getting rather long so I've started another specifically for the Midco burner and controls.
I'll let JStar comment on any specifics, but from my perspective the burner installation was pretty straightforward. The burner came in four pieces: the Midco controls cabinet, burner, blower, and valve train. I had to make a few modifications to the cabinet wiring to tie in my own controls cabinet, the flame rollout safety, and the solid state relay that acts as the "call for heat".
The valve train, starting from the blower, consists of a gas orifice, manual ball valve, Dungs FRG6 ratio regulator/zero governor, another gas orifice plate, and a Honeywell redundant combo gas valve. The blower is an ebm-papst RG175 electronically controlled centrifugal fan. Flame safeguard is via a Fenwal DS3565 gas ignition control. The only proprietary part is an RTC electronics board customized for Midco that regulates the blower speed. Except for the RTC board, everything is off-the-shelf parts.
Here are some photos of the burner installed on my Utica Starfire SFE steamer.
@ April 19, 2013 1:41 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion ProjectOops, the pic I posted was from before the equalizer valve was put in. Here's the as-installed pic.
Midco pics and video coming later today.
@ April 18, 2013 10:53 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion Project
@ April 18, 2013 10:52 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion ProjectIt's been an exciting couple of days here. Huge thanks to JStar and Edison for all their hard work. The de-knuckleheading of the near-boiler piping exceeded my expectations. Not only did JStar "de-bull" the main tee, he managed to rotate it 90+ degrees clockwise so the steam enters from slightly above and to the left rather than directly below. And that horizontal bullheaded tee that I thought we'd have to leave as-is? Nope. JStar capped that tee and split the main to the left of it. No more bullheads!
As for the Midco burner - absolutely smooth install and startup. And quiet - at my boiler's rated input I measured 71 dB 18" behind the blower, compared to 86 dB for the Beckett oil burner. Biggest concern was whether my DIY controls would actually operate this burner, but weeks of bench testing paid off. It'll take some time to tune the pressure controller, but overall I'm quite happy with the performance of the system.
Midco was interested enough in this project to send a rep to "site" (that's my basement). Their man stopped in briefly this afternoon and will be back tomorrow with his combustion analyzer to fine tune the burner controls.
Here are some pics of the de-knuckleheading. I'll post pics of the burner tomorrow, and maybe even a link to video of the burner in operation.
@ April 16, 2013 6:44 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion ProjectThis drip line from the northeast main ties into a sloping return from the northwest main about 22" off the floor. When the old coal boiler was in place, the water line was well above this point so it was a wet return, As it happens, the current boiler's water line is also about 22" off the floor, so depending on where you are in the cycle and how much pressure is in the system, this tee is alternately wet and dry. There's usually some water hammer here for a couple of minutes about 10 to 15 minutes after the boiler fires.
JStar is going to re-route the drip so that it ties into the wet return at floor level, which is off the right side of the picture.
@ April 16, 2013 1:05 PM in Venting risers after the supply valve?Hi Jim, I assume you're converting from oil to gas. Don't know the codes in your area but you'll most likely need a metal chimney liner. Even if it's not required by code it's still a good idea.
Do you have gas service already? Make sure you account for the btu requirements of all your gas appliances. I had to have a larger capacity gas meter installed, and we'll be running a larger service line into the house to accommodate the Midco burner.
How do you heat your domestic hot water now? Tankless coil? Icesailor shared an interesting and inexpensive indirect solution that he's been installing for years. It's the fourth post down in this thread: http://www.heatinghelp.com/forum-thread/141007/Tankless-coil-into-water-heater-tank.
At my house it's just my wife and I, so a couple of years ago I put in a "scheduled hot water" system using an old setback thermostat I had around, a flow switch, and a time-delay relay hooked up to the aquastat on the tankless coil. It's relatively cheap, and it cuts my non-heating season fuel usage by 50% or more versus aquastat-only control. The downside is that if you want hot water during a scheduled "off" period, you need to wait a few minutes for the boiler to heat up. If you're interested, send me a PM and I can give you some more details.
@ April 16, 2013 11:16 AM in Venting risers after the supply valve?Forum member jpf321 put together a spreadsheet to calculate venting requirements and make recommendations for Gorton and Hoffmann vents.
You can get Excel and OpenOffice versions of the worksheet here: http://www.ypgmedia.com/heatinghelp
It doesn't have a selection for risers, but you can just select "Main" in the "RadType" column and set the pipe size to the diameter of your risers.
@ April 15, 2013 8:57 PM in A Steam Odyssey: Midco Low-NOx Burner Oil to Gas Conversion ProjectHere's a schematic of the current system piping, and a couple photos of the mains and the main tee.
The mains configuration has me wondering what the Dead Men were thinking when they installed this 120 years ago. It has what conventional wisdom tells us are two big no-no's; a vertical bullheaded tee from the header into the main, and a horizontal bullheaded tee into the mains along the wall.
The main tee is 3x4x3. To the left is a 3" main serving 362 sq ft of radiation on two 2" branches totaling 95 feet in length. The right side is bushed down to 2" pipe serving the 32 foot long main along the wall with 251 sq ft of radiation. The 4" port is bushed down to 3" and again to 2". The original coal boiler was probably piped right into that 4" port, and the bushings added when old man coal was replaced.
With the new header, we're going to tempt fate a little here and second-guess the Dead Man by capping the right hand side of that main tee to eliminate the bullhead, and running separate takeoffs to it and the mains along the front wall. The horizontal bullhead on the front wall will still be there; we think it's more trouble than it's worth to remove that tee and have three takeoffs from the header.
Would appreciate comments/opinions on why it's piped that way to begin with, and/or if there are compelling reasons to NOT split the mains.