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New boiler and slant-fins

TerrS
TerrS Member Posts: 49
edited September 15 in Radiant Heating
Hi, I have read and been reading a ton of information on here and learned a ton but haven't seen a good conclusion to boiler replacements with slant-fins.

So I have a 1903 2.5 story house, that has around 8ft, sometimes 10ft on of slant-fins in each room.  My vintage boiler is 31years old and in-order to keep warm in SW PA, I have to keep the water temperature right around 180 degrees, yes it fluctuates with my aqua smart  control but in jan-march we avg 18 degrees. My gas bills are killing me at $350mo and can't wait until this winter season to knock my socks off..

So I have had 3 estimates so far. And pricing seems also wildly different for a 120btu boiler, no combination.

I am looking for help/recommendations? Please???
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Comments

  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    edited September 14
    You’ll have to remove those prices. 

    Why do you think the boiler is causing your heat monthly bills? How much gas (not $) did you use last year? What is the total linear length of baseboard? 
  • pecmsg
    pecmsg Member Posts: 3,063
    Get a heat load/loss done on the building. 
    Slant Fin has a online one that’s fairly accurate. 
    Then take it from there!
  • hot_rod
    hot_rod Member Posts: 16,875
    180 is not an unreasonable temperature to run a fin tube system. Does it keep the home warm on the coldest days?
    How many feet of fin tube? what size size the boiler?

    Oversized boilers tend to short cycle which can drive down efficiency, drive up fuel consumption 

    As suggested above first a load calc, then a measure of the fins, then see how it all matches up

    Spend money tighten up you home as much as possible, window leaks, weatherstripping, add insulation if possible. The lower the heat load, the left fuel needed.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    kcoppIntplm.
  • TerrS
    TerrS Member Posts: 49
    edited September 15
    Thanks, so my vintage boiler is 150btu input and 113 btu output. And with the water at 180 my house stays warm, at the expense of my wallet. As far as ft of slant-fin, there is about 8ft per room. So 4bd, plus living/dining room, so 32+16, my kitchen has a kick and a 3ft buderus, which throws tons of heat, even with only 60% flow. The bathroom has the same but 2ft buderus and plenty warm. When I first moved in 31 years ago, I froze because they set only to about 165, which took me 2-3yrs to ask the right questions to get heat. We set to 180 or 185 and those issues went away.

    Now it's a pure, spend money to save in few bills and maybe more comfort, meaning I only keep my house at 68 during the day and set back to 64 degrees at night. I have a gas fireplace to keep the living room warmer while we are watching TV
  • TerrS
    TerrS Member Posts: 49
    You’ll have to remove those prices. 

    Why do you think the boiler is causing your heat monthly bills? How much gas (not $) did you use last year? What is the total linear length of baseboard? 
    I use around 300 therms per month jan-march. With around 50ft of slant-fin thru-out my rooms

  • TerrS
    TerrS Member Posts: 49
    pecmsg said:
    Get a heat load/loss done on the building. 
    Slant Fin has a online one that’s fairly accurate. 
    Then take it from there!

    I have done that, and even though. I have insulated as much as I can without totally ripping apart everything most all wall have blown in insulation. Calculations are around 70k btu needed, infact that's what the last heating guy came in and told me. The consistent part of all my bid. Is the 120btu boiler based on my house size.
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    If 53 ft (check my math) can keep the house warm according to you at 180, then your heat loss is low - like 35kbtu. That old boiler is wasting fuel shortcycling. But that doesn’t jive with using 300 therms per month unless you’re wasting a lot of fuel. The gas fireplace is also probably inefficient too. I assume you use gas for water heating too? Anything else?
  • TerrS
    TerrS Member Posts: 49
    If 53 ft (check my math) can keep the house warm according to you at 180, then your heat loss is low - like 35kbtu. That old boiler is wasting fuel shortcycling. But that doesn’t jive with using 300 therms per month unless you’re wasting a lot of fuel. The gas fireplace is also probably inefficient too. I assume you use gas for water heating too? Anything else?
    Yes your math is correct. My gas usage non-winter with my hot water heater and gas dryer, is around 25 therms. I have watched my boiler. Water starts at 68 degrees, takes 20 minutes to start producing heat. Ie around 125 degree water and kick radiator starts blowing. The slant-fins really don't throw real heat until 160 and good heat at 180. On really cold days it's probably more efficient because it runs more often not losing the energy from 68-130 water heating.

  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    edited September 15
    If your heat loss is so low, then you don’t need a big boiler! If the max you can emit is 35k + kick space heater, bigger is just wasting fuel and money and making the system less responsive. 
  • pecmsg
    pecmsg Member Posts: 3,063
    TerrS said:


    pecmsg said:

    Get a heat load/loss done on the building. 
    Slant Fin has a online one that’s fairly accurate. 
    Then take it from there!

    I have done that, and even though. I have insulated as much as I can without totally ripping apart everything most all wall have blown in insulation. Calculations are around 70k btu needed, infact that's what the last heating guy came in and told me. The consistent part of all my bid. Is the 120btu boiler based on my house size.


    If the calculations say 70K then that's all you need! In fact, going to 120 will probably use more energy. The only way to save money is tightening the envelope reducing the heat loss!
  • fentonc
    fentonc Member Posts: 133
    If you’re using 275 therms/month and your system needs 180F water to meet your heat loss, the main problem is that your home’s heat loss is just very high. Adding more baseboard would allow you to provide the same BTUs at a lower water temperature, but that’s all it does. If you can get the water temperature below 135F or so, you could gain efficiency from using a condensing boiler (even if you needed to raise the water temperature on the coldest days via an outdoor reset scheme), but just replacing the boiler or the baseboards might do nothing to lower your fuel usage.
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    @fentonc even if design temp needs 180, the system could still condense the majority of the winter if @TerrS went the mod con route. I think the usage comes from a massively oversized boiler, an inefficient fireplace, the dryer and the water heater. I don’t want the same oversizing mistake made again if a replacement is chosen. 
    fentonc
  • TerrS
    TerrS Member Posts: 49
    pecmsg said:
    pecmsg said:
    Get a heat load/loss done on the building. 
    Slant Fin has a online one that’s fairly accurate. 
    Then take it from there!

    I have done that, and even though. I have insulated as much as I can without totally ripping apart everything most all wall have blown in insulation. Calculations are around 70k btu needed, infact that's what the last heating guy came in and told me. The consistent part of all my bid. Is the 120btu boiler based on my house size.
    If the calculations say 70K then that's all you need! In fact, going to 120 will probably use more energy. The only way to save money is tightening the envelope reducing the heat loss!
    So follow my logic here, as maybe I have not read enough. Remember my current boiler is 150/113. And the 3 HVAC people so far, have all quoted me 120btu, 95% condensing boiler.

    Realizing I didn't do this 31+ years, they only put about 85ft of slant-fin in this house and they spread it across 4 zones. Except they only put one pump and one thermostat. So 3 zones are 3/4 copper. And 1, 1" copper, all go into a single 1-1/4 manifold. This is on the supply and return lines.

    From my very limited knowledge and living in this house for 31 years, the fins need 180 degree water or I freeze due to the lack of enough radiation. Now add that to my question of if the water starts at 180. Then divides into 4 zones, I am only seeing around a 10-15 degree drop on my return side, I still need to verify this somehow, but in looking at my boiler temperature it never swings when the return water arrives.

    So jan-march here in Pittsburgh. It's in the 20s, and need the 180 degree water, maybe slightly less, but not to the point where I think I would get to the condensing temp of 140.

    If I am correct, I am leaning towards an 85% cast iron boiler with only 2.8 gallons in the boiler and a newer improved jacket, should heat the water quicker and more efficiency going from 68 degree to 180 degree water

    True??

  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    edited September 15
    Hold on @terrS - how many linear feet of baseboard is there? You’ve given multiple lengths. If 85 ft keeps the house comfortable on the coldest days, your heat loss is about 50kbtu and the calculations giving 70kbtu are padded 40+%. All the installers are selling bigger boilers than you need in that case. Bigger is not better! 

    In terms of condensing, if you need 180 at your design temperature (maybe around 5 degrees?) you’ll use a lower temperature the rest of the winter. As you can see, if you use 50kbtu at design temp, you’ll use about half of that at 35 degrees, which allows you some condensing temperatures throughout the coldest months. There are pros and cons to condensing boilers, but you’ll be condensing a lot if you go that route. 
  • TerrS
    TerrS Member Posts: 49
    Hold on @terrS - how many linear feet of baseboard isorry s there? You’ve given multiple lengths. If 85 ft keeps the house comfortable on the coldest days, your heat loss is about 50kbtu and the calculations giving 70kbtu are faulty. All the installers are selling bigger boilers than you need in that case. Bigger is not better! 

    In terms of condensing, if you need 180 at your design temperature (maybe around 5 degrees?) you’ll use a lower temperature the rest of the winter. As you can see, if you use 50kbtu at design temp, you’ll use about half of that at 35 degrees, which allows you some condensing temperatures throughout the coldest months. There are pros and cons to condensing boilers, but you’ll be condensing a lot if you go that route. 
    Sorry for the confusion, I have 4 floors in my house, if I include my attic and basement which have slant-fins run. My previous total I was only counting the main and second bedroom floors. In the calculations they might be important but since I don't live in those 2 areas, I forget about them, even though boiler water goes thru them.

    So according to my gas bill as I just verified, jan and Feb of 2022, the avg temp was 29 degrees. And those months I used around 220 therms. I apologize for the 300 number I gave earlier, that was the year before I put the aqua smart on the try and help the boiler be smarter than the dummy mechanical L8124. As everyone is aware, my natural gas prices have doubled.

    So since I can't refer to pricing, I will say life span of 15 years condensing boiler, to save $125 month over 3 months, makes 0 sense. However selling a house with a 31year old boiler is difficult also. So figuring 5-7 years I want to live here, I can justify an 85% boiler cost.

    Hot_water_fan
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    Excellent, keeping in mind that it’s the different in cost between the 95% and 85% that matters, not total cost. 

    Make sure the new boiler is not oversized. 80kBtu input/ 68kbtu output is the max you need. 
  • TerrS
    TerrS Member Posts: 49
    Excellent, keeping in mind that it’s the different in cost between the 95% and 85% that matters, not total cost. 

    Make sure the new boiler is not oversized. 80kBtu input/ 68kbtu output is the max you need. 

    Please understand here. I am not an expert by any stretch of the imagination. I do IT work but I know how to read. Maybe too much.....

    But The 3 hvac guys all quoted a 120 btu 95% boiler. If I am understand you, a 100btu would work better, be around right sized, accounting for heat loss and my slant-fin radiation?

    This why as a homeowner I am at the mercy of the heating company, when I start to question, they get all defensive. But in my mind, they just gave me a quote that I had to make justified sense.

    Thanks for your help!
  • TerrS
    TerrS Member Posts: 49
    Last question hopefully. Does 85% to 95% efficiency, directly relate to savings?  Meaning my old boiler 150/113 is only about 78% efficient. So even going to an 85% increases almost 7% or 17% if a high condensing boiler would work, assuming cost difference?

    Does that correlate to gas bill $$$$?

    Thanks again


  • KC_Jones
    KC_Jones Member Posts: 5,113
    When you say you need 180 degree water, we need clarity on the current function of your system. In order for you to actually "need" that, the boiler comes on, gets to 180 and doesn't shut off....ever. I think some of the details you are missing here is it's not what's temp is being supplied it's what temp and how much time it's being supplied for. With baseboard like you have they will cool down fairly quickly. So it's really about the average water temperature being supplied, not the maximum temperature being supplied.

    You had stated that the boiler cools down between cycles, if it's cooling down a significant amount then so are the baseboards and you actually aren't heating with 180 degree water, you could be at an average temp of 150 or lower to heat the house. That's where the newer boiler controls with a condensing boiler come in. The boiler will be set up with outdoor reset (which will need to be tuned to your house) and supply the water temperature that is required for the conditions you have. Believe it or not, it's much more efficient to fire the boiler as continuously as possible with lower water temperatures, than it is to function as you are now which is on max, off for a while, on max again. All the reheating of the boiler tends to be wasteful.

    The contractors aren't sizing the boiler properly because they are depending on the turn down ration of the condensing equipment to "reduce the size" of the boiler for the actual need. Also they don't want to do the heat loss of the house for reasons I could speculate on, and none of them are kind to the contractor.

    Based on what you have posted so far, most likely you need one of the smaller, if not the smallest boiler made, and it may even be too big.

    If you want a reality check, give us the total amount of baseboard in the house, and we can tell you what the system is capable of. The system output is limited to a maximum of what the baseboard is able to do. The standard slant fin baseboard is rated ~600 btu per foot at 180, now in reality since the water is cooling as it flows through you are maybe at 170 average temp and that would be at most 550 per foot. So feet of baseboard X 550 will tell you the maximum your system can handle. This isn't for boiler sizing, but is a reality check on how much the boiler they are proposing may be oversized. Just to be very clear, if the baseboard is capable of 50,000 BTU, it doesn't matter if they hook up a 250,000 btu boiler, the system will output 50,000, the boiler will just cycle a whole bunch of times to "reduce" it's output. The extra boiler output is 100% waste and does nothing for you and can actually hurt efficiency.

    If they do a modulating condensing boiler then those can regulate their output down, but you still have some limit based on the upper end. They are typically set up with a turn down ratio, and since that ratio is based on the maximum output, it moves the bar on the minimum output up. The more you read and learn about the modulating boilers, the more you realize it's more about the minimum output than the maximum. The maximum of almost all small boiler will cover the load of most average houses. You don't need to go very big (100k btu and higher) until you start talking about uninsulated houses, or mansions 4000 sq ft and bigger. If it's modern construction that square footage moves up to probably double that before you need higher output.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    hot_rod
  • TerrS
    TerrS Member Posts: 49
    edited September 15
    KC_Jones said:

    As stated above on my main 2 floors I have only about 32ft - between 4 bedrooms. 16ft between  living room/dining room. And a 3ft buderus radiator and kick in my kitchen.

    My boiler works fine, cycling when heat is required by the thermostat. Water heats to 180, boiler turns off. Waits for a 20 degree drop. Fires again and rinse and repeat until thermostat is satisfied. That can be 30 minutes to and hr at a time depending on temperature outside.

    As I said above, when I first moved into the house the l8124 was only set to around 170 degree and we froze.  not understanding why as they said boiler was brand new before I bought the house. I had an HVAC friend come over and look and found the water temperature to be low. After we set to 180. I never had another being cold issue as it would radiate enough to warm the house. Remember the fins are outside the scope sortof here, meaning I can't add more. Very cost prohibited.

    So since the boiler is 31 years old and is close to end of life, I am asking this forum for options?

    You are right in they are counting on the modulation factor for burner. This then comes down to price to install 95% and 85% new boilers and payback time.

    I need a boiler to sell the house, what I put in is up for debate, given my 5-7yr timeline.


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,633
    edited September 15
    If you are sure that the home will be sold, Then go with the lower cost. the savings payback on the difference will be in the 5 to 10 year range, and there are less moving parts to fail on the lower cost option.

    I owned my "temporary house" for over 40 years and now my son is living there. He is going to start his family soon. If I only knew then, I would have made different choices in those first 7 years
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

    GGross
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    But The 3 hvac guys all quoted a 120 btu 95% boiler. If I am understand you, a 100btu would work better, be around right sized, accounting for heat loss and my slant-fin radiation?

    This why as a homeowner I am at the mercy of the heating company, when I start to question, they get all defensive. But in my mind, they just gave me a quote that I had to make justified sense.


    You have 85ft of baseboard (and a toe kick heater - any other emitters?). 85 ft * 600 btu/linear foot at 180 degrees means you can output at MAX about 51,000 btu (that's if the AWT is 180, which it isn't. Just the supply is 180). With the knowledge that your house is comfortable on the coldest day with 180 F water, your heat loss is less than or equal to 51,000. It cannot be more than 51kbtu, so whether they recommend a 120,000 btu or a 12,000,000 btu boiler, the amount of heat those baseboards can provide at 180 F is capped at 51,000 btu. Yes, a 120,000 btu condensing boiler can modulate, but a 80,000 btu condensing boiler can modulate better. If you don't go the condensing route, you can size to output about 70,000 btu, so probably something close to 80,000 input.

    Last question hopefully. Does 85% to 95% efficiency, directly relate to savings? Meaning my old boiler 150/113 is only about 78% efficient. So even going to an 85% increases almost 7% or 17% if a high condensing boiler would work, assuming cost difference?

    Does that correlate to gas bill $$$$?

    Thanks again


    It is not an exact science. A 31 year old boiler that's way oversized will not perform as rated since idle losses will be large. So you could save more. However, there's probably 0 payback in replacing a boiler that's still working.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,633
    By the way... Slant Fin is a brand name, but all of their current radiators have perpendicular fins. I wonder why?
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

  • TerrS
    TerrS Member Posts: 49
    Thanks that finally made sense. That I am really capped at the 51k btu because of how many feet of slant-fins I have!!

    Boiler size double that is way oversized and a waste

    Hot_water_fan
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,522
    What sort of shape are your baseboards in? Are they all open the way they supposed to? Are the covers affixed properly? Are they open?
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    Thanks that finally made sense. That I am really capped at the 51k btu because of how many feet of slant-fins I have!!

    Boiler size double that is way oversized and a waste


    Yup, if that's the extent of your radiation that's about all you can do! Even temperature wise, you can't increase it much from here so truly a waste to go bigger.
  • TerrS
    TerrS Member Posts: 49
    What sort of shape are your baseboards in? Are they all open the way they supposed to? Are the covers affixed properly? Are they open?
    Most are in good shape. Many have new covers even. The fins not overly bent, etc. They seem to put off heat if water is at 180+. So I am going with a 101k output new model because @Hot_water_fan made me walk my house (j/k) to find everything and not guess with how many feet i really have and I missed. I am at 84600 btu max.

  • pedmec
    pedmec Member Posts: 290
    Am i crazy or does 85' of baseboard sound right? Average of 20' per floor. That doesn't sound right unless you got an extremely small and well insulated house.

    If those numbers are accurate and you have 4 zones that would explain the high fuel cost. Your heating up the chimney more than your heating up your living area. you can't possibly expect to transfer roughly 12k btus per zone @180 when one zone is calling. i can't imagine the short cycling. You are resetting the supply temperature so that makes it even worse as its going to satisfy the target temperature suddenly.

    If it was me i would add more baseboard. Adding more baseboard will allow the boiler to have longer run cycles. It will also set you up perfectly to change to a mod-con boiler. You can get the most out of your condensing boiler at lower return water operating temperatures.

    I'm guessing that they are thinking that you mentioned an indirect fired water heater might be added down the road. That might explain the size of the boiler. Just an educated guess
  • TerrS
    TerrS Member Posts: 49
    @pedmec not crazy, but after Hot_water_fan questioned. I walked my house. Got 106ft plus 2 buderus rads and a kick. That total another 17k btu. So after all is said and done I am looking at around 90k max. So I will purchase the 101k btu output model. Just to add in for heat loss.


  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    edited September 15
    @TerrS the radiation is the max you can emit, not your heat loss. I included the earlier calculations to show that a boiler exceeding your radiation by 3x (at the time, thank you for remeasuring) was obviously too big. The boiler should be sized to heat loss, not radiation capacity.

    So according to my gas bill as I just verified, jan and Feb of 2022, the avg temp was 29 degrees. And those months I used around 220 therms.


    If you're using 220 therms in January and assuming 20 of those are DHW, dryer, etc., that means you're putting 200 therms into your heating system. An average temperature of 29, means monthly heating degree days of (65-29)*31 days = 1116 heating degree days at 65 base temp. Input BTUs of 200 therms * 100,000 btu/therm = 20MMBtu. So you used 20MMBtu across 1116HDD, or about 18,000btu/HDD. Assuming 78% of those BTUs didn't go up the chimney, your heat loss is closer to 18,000*.78*60HDD (design day) /24 = 38kbtu/hr. A long way of saying that a 80,000 btu modcon is the biggest boiler you need. If going with a non-modulating cast iron boiler, you can go smaller.
  • KC_Jones
    KC_Jones Member Posts: 5,113
    Just because the system can output that, doesn't mean you are using it.

    Remember we are talking about BTU/Hour. So unless your current boiler is running 24/7 with 180 water you are not using 90k BTU's, probably not even close. As show above by @Hot_water_fan more like 1/3 that.

    Also of note to the above calculations that you just got for free, is more effort than the people you are thinking about paying are willing to do. Makes one scratch their head doesn't it?

    I'm just a homeowner, I feel your pain.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    JakeCK
  • TerrS
    TerrS Member Posts: 49
    @Hot_water_fan yes, and I appreciate all your help and expertise. Like KC stated. As a homeowner I am at the mercy of the so called experts. But many times it just seems they are looking for the next Maserati payment.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,362
    edited September 15
    @TerrS

    Your calculations are all over the place and very confusing. No one can help you without the right information.

    1. Download the Slant Fin app and do an accurate heat loss.
    2. then see if the baseboard you have will heat the house and what water temp it will take.
    3. If you have areas of the house with baseboard and you don't live in them why heat them other than to keep piping from freezing
    4. Do all the insulating window and door upgrades you can to reduce fuel cost.

    I doubt the heating guys are driving Masareti's try doing the work yourself and you will see/
  • Hot_water_fan
    Hot_water_fan Member Posts: 730
    edited September 16
    1. Download the Slant Fin app and do an accurate heat loss.
    2. then see if the baseboard you have will heat the house and what water temp it will take.

    @EBEBRATT-Ed respectfully, I think @TerrS is done here. She has determined what her radiation can output and since she lives at the house, she knows the baseboard is sufficient. How can we use slant-fin to more accurately know her heat loss than what the usage tells? And even if it’s more accurate, is it meaningfully so? We’ve established 120kbtu is too big. 100kbtu exceeds the radiation too. So she can get a 80kBtu mod con and call it a day or if she wants cast iron she can go down a little to fit the load better. Not much else to do here. 


    TerrS
  • TerrS
    TerrS Member Posts: 49
    @ebebratt-ed so @hot_water_fan helped tremendously and yes a few of my calculations of baseboard feet were off originally. But this women can do more than to think. I have already helped put in 1 boiler with a friend, and will probably do mine with a friend. My biggest issues were calculating boiler sizes, because of what the HVAC people were telling me didn't seem right. They were over sizing it. It really seems to upset them when a woman starts questioning why!!!  But I have all my answers. Thank you.
    KC_Jones
  • hot_rod
    hot_rod Member Posts: 16,875
    It’s your home, the building structure that dictates the heat loss. No boiler or emitter can change that.
    Have you ever done a blower door test? It could point out some very inexpensive places to lower the heat load. The best money you can spend is lowering the liad

     I’d suspect the gas fireplace could be sucking heat out, even the sealed type leak heat out.  Sit in front of it on a windy day, do you feel drafts around the bottom or sides?  They run about 32,000 btu/ hr. I wonder if even 50% of that get into the heated space?

    A steep setback doesn’t always work out, a few degrees maybe, as long as it catches up before you get up🥳

    Go to www.dsireusa.org, click on your state to see what incentives are available to upgrade your system. In some areas the utilities will do free blower door test. They need to lower consumption also to have adequate supplies. You might find $$ for insulation or weatherstrip upgrades.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Larry Weingarten
  • TerrS
    TerrS Member Posts: 49
    @hot_rod as I stated above my house is 1903 vintage. The fireplace I converted, totally sealed the old flue, put slate and concrete on the sides and top, then put an 18k vent-free logset in. I can make my living like the Bahamas for pennies, because it's only using an ovens worth of natural gas. So it was the best investment I made to supplement heating my house and a backup source if I had boiler issues.

    Over the years I have updated the windows and blown in insulation into the walls as much as I could, new doors, etc. Is it as efficient as I would like NO, but the price I pay for living here I guess.  I also can't control where and how many of all the fin tubes they ran. I have made a few changes but just don't have the wall space.

    The conversation with @Hot_water_fan was really helpful because I am still learning the basics as to what goes into sizing a boiler. Understanding the limitations of the other components.

    If I was really ambitious, I would run 4 thermostats, and add zone valves/pumps to only really heat the areas needed, as to now sending water throughout the whole house.

    But everything has a cost and return on investment. And given our countries fuel cost have been traditionally low, it's never been a real issue, until the last 18months.

    As I also stated, but have been told, why replace a perfectly working boiler, and the answer is better technology.  I am leaning towards a 92k btu input 84% cast iron boiler. First because the tank only heats 2.3 gallons of water, instead of 6 gallons in my old dunkirk pw51, improved jacket insulation and technically a smaller burner size to heat enough water but not overkill.

    The cost involved in a modulation/condensing boiler, I would have to run new cpvc vents outside my house, replumb as the water connections majorly change. As well as running a condensate pump across my house as I have no drains besides my boiler. Work/costs of POSSIBLY saving that extra 10% if full modulation is achieved doesn't work out in savings unless you are at year 9. Every HVAC person says it's the best thing since sliced bread but when you start asking questions they can't quantify, because weather changes. In an ideal world. I would condense 4 out of 5 heating months and possibly taking my 200 therms to 100 or 150 a month, but again those saving are not realized until year 9.

    For example, $1 now, a therm times let's say I actually save 100 terms a month. Is around $175mo savings because gas/delivery charges x 5 months = $875yr possibly. Now multiple by 10+ and that will be my cost to install/recoup money invested.

    Thanks for everyone's helps.
  • hot_rod
    hot_rod Member Posts: 16,875
    You can regulate heat output at every fin tube section by closing down the damper, or covering some of the fins with aluminum foil. So those areas where you want less heat you can regulate to save some fuel. A poor man, or womans thermostat :)

    It's not realistic to keep rooms next to oner another 10° or more different, unless the walls between are insulated.

    Hot goes towards cold, so the colder the unheated space the faster the heat transfer from the warmer room. 5-8 degrees maybe?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TerrS
    TerrS Member Posts: 49
    @hot_rod I can tell you most of my house is consistent in temperature. And when I said about my fin tubes, I ment quantity or maybe quality in today's technology to give off more radiant heat/water temperature. I really can't or need to cover them.

    For example My attic is finished but Ciera 1950's vintage, it has 30ft of fin tubes, let's call it a waste because not an actual living space, but I have to send some water up there or the pipes would freeze. So I have a ball valve on my return zone and I only open it 1/4 of the way for the attic.
  • pecmsg
    pecmsg Member Posts: 3,063
    edited September 16
    TerrS said:

    @hot_rod I can tell you most of my house is consistent in temperature. And when I said about my fin tubes, I ment quantity or maybe quality in today's technology to give off more radiant heat/water temperature. I really can't or need to cover them.

    For example My attic is finished but Ciera 1950's vintage, it has 30ft of fin tubes, let's call it a waste because not an actual living space, but I have to send some water up there or the pipes would freeze. So I have a ball valve on my return zone and I only open it 1/4 of the way for the attic.
    Ball valves should be 100% opened or closed.

    Why are you heating an unconditioned space? That heater was probably installed for future renovation but hasten happened. If you're not going to finish the attic, I suggest your heating contractor cut the supply and return somewhere accessible and IF you decide down the road it can be reconnected.