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HVAC options / solicitation for a 1927 home in southern NH

exodusnh
exodusnh Member Posts: 18
edited June 17 in THE MAIN WALL
Hello all,

I was pointed to this forum from bogleheads.org.

I have a 1927 home in southern New Hampshire. It has a single-pipe steam system run by the original 1927 boiler that was reconfigured for oil. The system is in remarkably good shape.

Around 2000, the previous homeowners put in a high velocity AC system, a SpacePak air handler in the attic with a 1.5 ton Goodman condenser unit. The latter failed last year and was not replaced since the roof also failed. Staying dry beats out staying cool; the AC was put on hold. We are getting by with window units.

Obviously, my issue is oil consumption. There's about 1,850 square feet of conditioned space on two floors with a single zone. I use about 1,000 gallons of oil per year, and that's just keeping the house at between 64 and 66 degrees. The boiler and steam pipes are insulated (asbestos, of course) as far as I can tell, at least until the pipes run up. There's no insulation on basement ceiling. As expected, the basement stays relatively warm in the winter. I had thought that the heat was passively radiating through the floors and so never much thought about it. But then one of the members pointed out that the heat was going to ground through the uninsulated walls.

While the boiler has consistently tested as 78%-80% efficient, I've recently been told that's impossible. Even if the combustion efficiency is true, there's a lot of heat loss to the ground and out the original basement windows.

I know that the combination of high velocity AC and steam is an unusual configuration. A couple of members over a bogleheads gave me some really good information. My situation is not hopeless, which, frankly, it felt when I was hit with the final $1000 oil bill in April. (And, earlier this week when I realized that there's likely no relief coming and I could well be faced with $6,000-$10,000 of heating expenses this year.)

I would like to do "something" before the heating season really kicks in. I'd like to avoid dealing with asbestos mitigation for the time being. I do not need the AC repaired for this summer. The window units are sufficient. I have about 3/4 of a tank of oil, which should get me through November.

The most promising options seems to be a heat pump, either using the oil boiler as emergency backup or potentially installing a separate gas-fired boiler and a hydronic coil. I do have natural gas service to the house. My unscientific measurement of the black pipe is that it has a circumference of 3.25".

I do have a solar company coming by next week to discuss my options. My uneducated assessment is that I have a decent roof for solar, given the southern exposure and a 24x24 garage.

I realize this long post doesn't have a question. I guess that would be "what are my options?" and "who would you recommend for the work?" If there are vendors here, please take this as in invite to reach out.

If your question is going to be "what's your budget?", I don't have an answer for that because I simply don't know what kind of range is reasonable. My two requirements are avoiding the asbestos mitigation for now (unless there's a compelling argument otherwise) and not having to tear up the inside of the house to run ducts or re-pipe. I've been in the house for 17 years and don't see myself leaving anytime soon.

Thank you so much for your time and for tolerating such a long post!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 18,908
    edited June 17
    Your best options, in order, are going to be

    First, to assess that boiler. It probably is around 75% to 80% efficient, but no more than that. To do that you will need to hire a good technician to come in and thoroughly clean the boiler and adjust the combustion correctly -- with test instruments which he knows how to use.

    Second, your biggest bang for the buck is going to be locating and sealing as many of the draughts as you can. I'm going to bet that that hasn't been done. Then go around and figure out where you can add insulation without major problems -- particularly in the attic. A lot of this you can do yourself with materials from the local big box store.

    You may be tempted to replace windows. Don't. Instead, spend some time to make sure the existing windows are tight, and get good storm windows for them, either inside ones or outside ones. This is assuming you still have the original windows, of course. If someone put in "modern" ones at some point, they may need to be replaced.

    Next go around when the heat is on and make sure that the venting is adequate -- both on the mains and on the radiators -- and is well balanced. That can work wonders. Don't use big box vents -- but good ones are easily available.

    Now going back to the boiler. If it really is that old, you may want to contemplate replacing it, either with a new gas fired unit or a new oil fired unit. Now you are beginning to get into significant money, and it is unlikely that you will recover the cost of the replacement, but it's worth looking at.

    But -- KEEP THE STEAM! At least for the colder days. You can't beat the comfort -- or the efficiency. Which brings me to my last point.

    You indeed may want to consider a heat pump, at least for the shoulder seasons and to provide air conditioning if you really need it. If you have adequate ductwork -- unlikely, but strange things do happen -- you could use a ducted system. Otherwise, you may be able to use mini-splits to advantage.

    Last, on the asbestos. This is one of those questions. If the insulation on the pipes is in good shape -- not falling off or crumbling -- you can encapsulate it and it will be fine. Otherwise, you may want to hire someone to remove it, which is rather expensive, but if you do, put insulation back on all the steam carrying pipes. It's needed.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,987
    The first thing you should do is make sure your windows, doors and insulation are as good as possible. This will help no matter how you heat the house. Is there any insulation in the house walls and ceiling?

    Has any insulation been blown in the walls?

    1000 gallons of oil is not unreasonable for the square footage you have, it's just that the price is unreasonable now.

    Check in your state for any energy audit programs & blower door tests

    Once that is done, I would investigate whether a heat pump system is viable. Not sure if a heat pump can be used with a Space Pak system. Others will comment.

    Once that is done, I would consider the boiler replacement



  • Jon_blaney
    Jon_blaney Member Posts: 271
    Have you considered a wood stove. It is NH.
    ethicalpaul
  • ethicalpaul
    ethicalpaul Member Posts: 3,739
    edited June 17
    What is the exterior wall insulation situation? Just air? Seal the holes and if you can, insulate the walls if they are just air space. That sounds like a lot of fuel usage for that size house to me.

    But it's not the boiler's fault. As said above it's the cold air getting in and the heat going out. Do not let some HVAC guy tell you to put in a mod-con or something, keep the steam.

    I'm basically repeating what others said so you know there is a wide array of agreement. I'm a homeowner, not a pro but I've had two homes that size with oil heat.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • exodusnh
    exodusnh Member Posts: 18
    @Jamie Hall -- the boiler is definitely that old -- the company that made it filed bankruptcy in 1928 or 1929. It has been relined and I do have it serviced regularly. (Pic below.)

    @EBEBRATT-Ed, @Jamie Hall @ethicalpaul -- when the homeowners installed the central air system, I'm assuming they would have ensured the house was insulated. Electricity has always been expensive in New Hampshire (and New England in general) -- it would have been madness to install AC without it. The attic has blown-in cellulose. All of the windows, except those in the basement were replaced by them, sometime around 2000, which I'm guessing is also when the house was re-sided.

    There are two doors in the house that are original (and of course custom sizes.) There are storm doors in place, but we will be looking at tightening them up somehow this winter. We'll need to seal up the fireplace in the living room, since we do hear wind sailing through on windy days. This wasn't much of a concern with $2.50 oil...

    @Jon_blaney There's no place for it. All of the rooms on the first floor only have one exterior wall. And they're all windows. The house was built for fresh air in the summer and cheap coal in the winter. The rooms are very small -- the living room is the largest in the house at 12x15. There is no way to get heat through the house except via the passive transfer up the staircase.

    Here's a picture of the boiler:

  • exodusnh
    exodusnh Member Posts: 18
    edited June 17
    Oh -- while I await my other comment to be approved (I included a boiler picture, which why I assume it needed approval), I do have an energy audit coming in next Thursday. They called while I was replying.
    ethicalpaul
  • exodusnh
    exodusnh Member Posts: 18
    And in terms of air conditioning, yes, we do "need" it. New Hampshire gets just as hot and humid as Florida, though obviously not as early, often or for as long. But 4 weeks ago, it was in the upper 80s for several days. My GF has asthma and needs the air cooled and dehumidified. This time last year, it was 90+ for days in a row, which is when the condenser unit failed.
  • Hot_water_fan
    Hot_water_fan Member Posts: 511
    Air sealing, insulating and switching as much heating to heat pump as possible is about as good as you can do here.
    ethicalpaul
  • Steamhead
    Steamhead Member Posts: 15,329
    That's a "snowman" boiler. One of my Dead Men's Books says this type of boiler is about 40% efficient on oil, since it doesn't have much heat-transfer surface. I'll bet your stack temp is well over 500 degrees.

    First thing to do is replace it. Asbestos removal must be done according to the laws in NH. Might as well have them remove all the asbestos and re-insulate the pipes with fiberglass.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • exodusnh
    exodusnh Member Posts: 18
    @Steamhead, when I moved in, there was a tag in the unit showing 80%. I had it tested and they said 78% (or vice versa). I saw him jam the probe into the exhaust pipe.

    It's certainly possible that they're not measuring correctly OR the tools simply aren't calibrated for a 95 year old boiler.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,180
    edited June 18
    Combustion efficiency is just a measurement of the flame temperature minus the exhaust temperature. Since the thermometer needed to measure the flame temperature was very expensive back in the day, some scientists discovered that if you measure the excess air added to make the flame burn clean, you could determine what the flame temperature was. There was an easy way to measure Carbon Dioxide (co2) back in the day and charts were developed to calculate how much excess air was added to the flame based on the amount of co2 that was measured in a sample of the flue gas. This was all very scientific in the early days of oil heat. All that said, If you measure the co2 and the stack temperature you can look on a chart and see the combustion efficiency of the fuel in relationship to the flame temperature compared to the stack temperature. If the co2 measured 6% in the flue gas sample and the stack temperature is 400° the chart says that you are operating at 75.5% combustion efficiency. This means that a flue gas, of oil burning that has 6% co2, is about 1600°. That is a lot of excess air and a relatively low flame temperature. A modern oil burner can hace a temperature as high as 2400° with very little excess air, but if 1200° is going up the chimney to is only 50% efficient.

    The thing about these measurements is that to get the accurate flame temperature the flue gas sample must have no other gas from ambient air leaking in thru the boiler clean out door flue connection or the draft control. Any leaks will allow air that did not pass thru the oil burner in the combustion process. This leaked air will cause the sample to offer a false "Actual Flame Temperature" that was calculated over 100 hears ago by the combustion scientists that made that chart. By the way, today's combustion specialists still measure the flame temperature and have verified that the old charts are still accurate.

    The laws of physics don't change with the "new v. old" equipment.

    Now we use electronic measurement devices that measure oxygen in the flue gas sample and that is then converted to the excess air and the co2 numbers. They also have combustion efficiency measurements calculated right on the device. This is so you don't need to look it up on the chart.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • exodusnh
    exodusnh Member Posts: 18
    @EdTheHeaterMan thank you! By "not calibrated", I meant something like what you said regarding bypass air. In other words, the mechanical equipment that's 95 years old may behave in ways that a 25 year old tech might not realize they need to watch out for.
  • Jamie Hall
    Jamie Hall Member Posts: 18,908
    Agree with @Steamhead . Replacing that boiler with a nice new one, properly sized and piped, is going to make a nice dent in your fuel bill.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • exodusnh
    exodusnh Member Posts: 18
    @Steamhead -- I found the tests from 2014:

    CO2 Max: 15.7%
    O2: 13.0%
    CO: 178 ppm
    Fluegas temp: 463.2F
    EFF: 74.2%
    Ambient temp: 34.3F
    Draught: -0.04 in H2O
    Excess air: 152%
    CO2: 5.96%
    Undiluted CO: 469 ppm

    Regarding the CO, back in 2014, the guy told me to keep the front grill closed because "having it open was for coal."

    When the tech was here in January 2021, he said to keep it open. When I asked why, he said it lowered the CO and that they weren't as worried about that in 2014.
  • Hot_water_fan
    Hot_water_fan Member Posts: 511
    @exodusnh

    To bump up the complexity some, the combustion efficiency is important but not the whole story. Think of it like a ceiling - a boiler with 80% combustion efficiency might only put 50% of the oil into the house itself. Often there is huge variance between the two.

  • exodusnh
    exodusnh Member Posts: 18
    @Jamie Hall -- none of the HVAC companies will touch it without asbestos abatement, which I was hoping to avoid for now. When I last chatted with them, they said it would have to be removed around the boiler and partway up the pipes -- essentially enough room to let them make the connections, but not necessarily all the way.

    I realize this question is very location dependent, but does anyone have a rough idea of what that cost would be?

    In terms of replacement, I assume that while the unit gets an efficiency of 75%, that doesn't take into account the heat loss to the basement walls. The basement definitely stays above 60 degrees in the winter, but not warmer than the house. I assume with a new unit being 80% or so that the basement would wind up much cooler and might even require insulating the basement ceiling. (The floor is maple over some sort of planked subfloor.)

    I wish there were a way to measure the actual efficiency -- the ROI on a purported 75% vs 80% is a very long time.

    Anyone have recommended vendors in southern NH?

    Thank you to all for your replies. I do have other replies awaiting moderator review. Not sure why.
  • exodusnh
    exodusnh Member Posts: 18



    To bump up the complexity some, the combustion efficiency is important but not the whole story. Think of it like a ceiling - a boiler with 80% combustion efficiency might only put 50% of the oil into the house itself. Often there is huge variance between the two.

    @Hot_water_fan -- right, the wasted heat dumped into the basement and the into the atmosphere via the windows or ground via the foundation. Is there a more comprehensive test that takes those into account?
  • Hot_water_fan
    Hot_water_fan Member Posts: 511
    @Hot_water_fan -- right, the wasted heat dumped into the basement and the into the atmosphere via the windows or ground via the foundation. Is there a more comprehensive test that takes those into account?


    Up the flue too! I'm not sure of a comprehensive test - AFUE for new boilers is supposed to approximate short-cycling and idle loss better than combustion tests, but that's a lab test and falls short because it's a lab test.

    In terms of ROI, it might be hard to justify replacing the boiler. But since you're replacing the AC anyway, the incremental cost of adding in a heat pump is extremely low. It'll be more efficient and use a cheaper fuel.
  • exodusnh
    exodusnh Member Posts: 18


    Up the flue too! I'm not sure of a comprehensive test - AFUE for new boilers is supposed to approximate short-cycling and idle loss better than combustion tests, but that's a lab test and falls short because it's a lab test.

    In terms of ROI, it might be hard to justify replacing the boiler. But since you're replacing the AC anyway, the incremental cost of adding in a heat pump is extremely low. It'll be more efficient and use a cheaper fuel.

    "Up the flue" is certainly how all of this feels!

    Are you familiar with which heat pumps work with high velocity air handlers? I realize I'll need to replace the existing SpacePak unit.
  • Jamie Hall
    Jamie Hall Member Posts: 18,908
    Mix and match on heat pumps and air handlers is tricky. You might want to contact SpacePak directly. They make heat pumps, and very good ones.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 16,278
    check out dsireusa.org for some programs. Looks like 71 programs available for different types of buildings commercial or residential in NH.
    I think a blower door assessment would be tops on my list to identify "leaks" which are the largest energy thief.

    It may be getting tougher to find competent, qualified steam guys locally, anymore. You have a better chance in that side of the country.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • exodusnh
    exodusnh Member Posts: 18
    hot_rod said:

    check out dsireusa.org for some programs. Looks like 71 programs available for different types of buildings commercial or residential in NH.
    I think a blower door assessment would be tops on my list to identify "leaks" which are the largest energy thief.

    It may be getting tougher to find competent, qualified steam guys locally, anymore. You have a better chance in that side of the country.

    Thank you for the search tip. I have an energy auditor coming by Thursday. They didn't mention running that test, but I'll be sure to mention it to him.

    Between writing this message this morning and now, I do have a local HVAC coming by in July as an initial assessment. Between the information gathered here and over at bogleheads, I hope to have the beginnings of a good plan that doesn't involve me brokering a peace deal in Ukraine.
  • Steamhead
    Steamhead Member Posts: 15,329
    exodusnh said:

    @Steamhead -- I found the tests from 2014:

    CO2 Max: 15.7%
    O2: 13.0%
    CO: 178 ppm
    Fluegas temp: 463.2F
    EFF: 74.2%
    Ambient temp: 34.3F
    Draught: -0.04 in H2O
    Excess air: 152%
    CO2: 5.96%
    Undiluted CO: 469 ppm

    Regarding the CO, back in 2014, the guy told me to keep the front grill closed because "having it open was for coal."

    When the tech was here in January 2021, he said to keep it open. When I asked why, he said it lowered the CO and that they weren't as worried about that in 2014.

    469 PPM undiluted CO?!?!? That's wayyyy too high. This unit has some problems- maybe the flame is hitting the firebox, chilling it to the point where it makes CO. You should not need to leave the grille open to lower the CO.

    You don't want a heat pump as your only heat source in NH. Go here to see some contractor listings:

    https://heatinghelp.com/find-a-contractor/state/NH
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • exodusnh
    exodusnh Member Posts: 18
    Steamhead said:

    exodusnh said:

    @Steamhead -- I found the tests from 2014:

    CO2 Max: 15.7%
    O2: 13.0%
    CO: 178 ppm
    Fluegas temp: 463.2F
    EFF: 74.2%
    Ambient temp: 34.3F
    Draught: -0.04 in H2O
    Excess air: 152%
    CO2: 5.96%
    Undiluted CO: 469 ppm

    Regarding the CO, back in 2014, the guy told me to keep the front grill closed because "having it open was for coal."

    When the tech was here in January 2021, he said to keep it open. When I asked why, he said it lowered the CO and that they weren't as worried about that in 2014.

    469 PPM undiluted CO?!?!? That's wayyyy too high. This unit has some problems- maybe the flame is hitting the firebox, chilling it to the point where it makes CO. You should not need to leave the grille open to lower the CO.

    You don't want a heat pump as your only heat source in NH. Go here to see some contractor listings:

    https://heatinghelp.com/find-a-contractor/state/NH
    That was 8 years ago now. They didn't leave me out the nice print out last time they tested it (2021). I didn't know enough to ask any more. All I remember is I asked why he left it open, and he said that when it was closed, the CO went too high. He seemed rather nonplussed about the situation, but I'll be sure to mention it to them when I get them here to service it this year.

    The unit sucks A LOT of air when it's on.

    Have these contractors been vetted by the board, or is it a pure pay-to-play?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,987
    Your 5.9 Co2 is way low and your combustion efficiency (burner problem) is lousy. Who ever services this doesn't know what he is doing.

    I am sure you can get over 70% out of that boiler. You just need an oil burner guy that knows what he is doing.

    What kind of oil burner is on that thing. Make and model
  • Steamhead
    Steamhead Member Posts: 15,329
    edited June 18
    @exodusnh , is it possible to get a pic of the burner flame when it's on (BE VERY CAREFUL IF YOU TRY- Do NOT get so close that you risk getting burned)? It's OK if you don't want to risk it.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • exodusnh
    exodusnh Member Posts: 18
    Your 5.9 Co2 is way low and your combustion efficiency (burner problem) is lousy. Who ever services this doesn't know what he is doing. I am sure you can get over 70% out of that boiler. You just need an oil burner guy that knows what he is doing. What kind of oil burner is on that thing. Make and model
    It's Carlin 100CRD.

  • exodusnh
    exodusnh Member Posts: 18
    Steamhead said:
    @exodusnh , is it possible to get a pic of the burner flame when it's on (BE VERY CAREFUL IF YOU TRY- Do NOT get so close that you risk getting burned)? It's OK if you don't want to risk it.
    Here you go! It fired right up, as always. (Except when the flame sensor failed.)

  • exodusnh
    exodusnh Member Posts: 18
    Here is what I believe is the main vent. Presumably, the Teflon tape indicates it is "modern", but it is at least 17 years old as I never replaced it.

    The perspective is a bit off. It's roughly the length of my hand, wrist to middle finger tip.


  • bburd
    bburd Member Posts: 331
    edited June 18
    Regarding the flame photo, the nozzle angle is too narrow for that combustion chamber and you are getting flame impingement on the rear wall. That is probably why the CO is elevated.

    You should probably have an 80° nozzle. Did the tech write down what nozzle is in there?

    As noted above, you need an oil burner tech who really knows what they are doing. Perhaps talk to the service manager, or try a different company.

    For boilers designed to burn oil, the manufacturer specifies the nozzle angle and spray pattern for various firing rates based on factory tests. For a coal conversion job, this usually must be determined by trying several to find a good fit, testing with a combustion analyzer. It will take time and cost money, but is well worthwhile if you will continue to run that boiler.

    Bburd
  • exodusnh
    exodusnh Member Posts: 18
    bburd said:
    Regarding the flame photo, the nozzle angle is too narrow for that combustion chamber and you are getting flame impingement on the rear wall. That is probably why the CO is elevated.

    You should probably have an 80° nozzle. Did the tech write down what nozzle is in there?

    As noted above, you need an oil burner tech who really knows what they are doing. Perhaps talk to the service manager, or try a different company.

    For boilers designed to burn oil, the manufacturer specifies the nozzle angle and spray pattern for various firing rates based on factory tests. For a coal conversion job, this usually must be determined by trying several to find a good fit, testing with a combustion analyzer. It will take time and cost money, but is well worthwhile if you will continue to run that boiler.

    No, that was never documented as far as I know. I think I've only had the nozzle changed out twice. One time, the tech put in a 1 gpm nozzle to save oil. The next one replaced it with 1.25 gpm.
  • bburd
    bburd Member Posts: 331
    The nozzle should generally be changed every year or two. They wear out, and combustion efficiency suffers.

    Bburd
  • Jamie Hall
    Jamie Hall Member Posts: 18,908
    Changing the firing rate -- nozzle size -- to "save oil" is just wrong -- although it may solve other problems. Think about it for a minute: your house loses some certain amount of BTUh. You need to supply that lost BTUh to keep the house at the temperature you want. There is a fixed amount of BTU in a gallon of oil. Therefore, regardless of firing rate, you need to burn a fixed number of gallons of oil per hour to meet that BTUh requirement. On that basis, it doesn't make one bit of difference what the firing rate is -- a bigger nozzle will just run for less time.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • exodusnh
    exodusnh Member Posts: 18
    Changing the firing rate -- nozzle size -- to "save oil" is just wrong -- although it may solve other problems. Think about it for a minute: your house loses some certain amount of BTUh. You need to supply that lost BTUh to keep the house at the temperature you want. There is a fixed amount of BTU in a gallon of oil. Therefore, regardless of firing rate, you need to burn a fixed number of gallons of oil per hour to meet that BTUh requirement. On that basis, it doesn't make one bit of difference what the firing rate is -- a bigger nozzle will just run for less time.

    Oh, I get it. You just never know what was done before. When the first guy suggested it, I figured he knew what he was talking about. Based on the face of the second tech, I realized it wasn't a sensible move.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,180
    edited June 18
    bburd said:

    Regarding the flame photo, the nozzle angle is too narrow for that combustion chamber and you are getting flame impingement on the rear wall. That is probably why the CO is elevated.

    You should probably have an 80° nozzle. (don't do this) Did the tech write down what nozzle is in there?

    As noted above, you need an oil burner tech who really knows what they are doing. Perhaps talk to the service manager, or try a different company.

    For boilers designed to burn oil, the manufacturer specifies the nozzle angle and spray pattern for various firing rates based on factory tests. For a coal conversion job, this usually must be determined by trying several to find a good fit, testing with a combustion analyzer. It will take time and cost money, but is well worthwhile if you will continue to run that boiler.

    The Carlin burner operates best with a 60° nozzle. the photo of the flame shows improper flame retention to the burner head. that is usually a result of the oil pressure and air adjustment of the burner. This is a picture of what you want the flame to look like.

    The air flow pattern of a flame retention burner does not follow the "Old School" thought process of matching the nozzle spray angle to the combustion chamber shape. If your technician uses the manufacturer's recommended nozzle specification, then adjust the air handling parts as designed by the manufacturer, you can shorten the flame so as not to impinge on the back wall.

    Also to take a flame picture you need a slower shutter speed in order to see the average overall shape of the flame the way the human eye would see it. That picture you posted may not be what you actually see in real time.


    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • exodusnh
    exodusnh Member Posts: 18
    Regarding the flame photo, the nozzle angle is too narrow for that combustion chamber and you are getting flame impingement on the rear wall. That is probably why the CO is elevated.

    You should probably have an 80° nozzle. (don't do this) Did the tech write down what nozzle is in there?

    As noted above, you need an oil burner tech who really knows what they are doing. Perhaps talk to the service manager, or try a different company.

    For boilers designed to burn oil, the manufacturer specifies the nozzle angle and spray pattern for various firing rates based on factory tests. For a coal conversion job, this usually must be determined by trying several to find a good fit, testing with a combustion analyzer. It will take time and cost money, but is well worthwhile if you will continue to run that boiler.
    The Carlin burner operates best with a 60° nozzle. the photo of the flame shows improper flame retention to the burner head. that is usually a result of the oil pressure and air adjustment of the burner. This is a picture of what you want the flame to look like. The air flow pattern of a flame retention burner does not follow the "Old School" thought process of matching the nozzle spray angle to the combustion chamber shape. If your technician uses the manufacturer's recommended nozzle specification, then adjust the air handling parts as designed by the manufacturer, you can shorten the flame so as not to impinge on the back wall. Also to take a flame picture you need a slower shutter speed in order to see the average overall shape of the flame the way the human eye would see it. That picture you posted may not be what you actually see in real time.

    Thank you for the information! Tomorrow, I'll take a video of the flame (and then have to figure out where to host it). There is one pic I took at a worse angle where my phone took several shots in quick succession. They flame shape didn't look terribly different, but since it's not the same angle, I can't be sure.
  • Steamhead
    Steamhead Member Posts: 15,329
    edited June 19
    Carlins generally don't like 80° nozzles, but there are exceptions.

    The manual specifies 70° hollow nozzles for 0.5 to 0.75 GPH flow rates, and 60° semi-solid nozzles for higher rates. Note that these are Hago nozzles, so one might have to experiment if using the more-common Delavan nozzles. Their advertised spray angles are a bit different in practice. I've found that when substituting a Delavan where a Hago was specified, we sometimes have to use the next wider spray angle.

    The manual is here:

    https://inspectapedia.com/heat/Carlin-100CRD-101CRD-Oil-Burner-Manual.pdf
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