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Gas Boiler Options

polo735polo735 Member Posts: 9
Hi all,

I am a new homeowner looking to replace a 20 y/o slant/fin oil boiler. I live in new england and my home is a 1930's cape with living space of about 2500 sqft.

The house has baseboard copper fin units on the first floor and cast iron radiators on the second floor. My current hot water heater is a gas fueled unit installed in 2009. My home has had some insulation done. A blower door envelope procedure was done to improve heat loss, however the basement and attic have minimal insulation.

Over the course of the last 2 weeks I've been receiving estimates for direct venting, high efficiency condensing boiler (95+afue)with an indirect hot water heater. I have also received quotes for traditional boilers with afue of 83%.

I have yet to decide between the lower or higher efficiency options. It will be necessary to reline our chimney if we opt for the less efficient option. I am attracted to this option for the low initial cost and the ability to use heat and hot water during power outages.

As I understand the benefits of the high efficiency models are $ savings through less fuel usage and the ability to avoid the cost of lining my chimney.

I have been given prices for Weil-McLain and Utica boilers with around 83% afue.

The high efficiency models I've received quotes for are a Weil-McLain WM97+, a Burnham Alpine and Buderus GB142.

I am leaning toward the high efficiency option but not ruling out other.

Unless someone has a good argument to stay with a conventional ~83% afue boiler... Which of the three condensing boiler models would you recommend?

Thanks very much for any input.


  • IronmanIronman Member Posts: 5,564
    Boiler Options

    Well, someone's given you some bad info: no modern boiler will operate without power, neither will the controls or circulator(s). Eliminate that guy from your contractor choices.

    That brings me to the most important boiler choice: the installer. A knucklehead installer wiil mess up the best boiler made and a good installer can take any boiler and make it work like a champ. Concentrate on getting a good, competent hydronics man. Ask questions. Ask for references with photos of his work. Check the contractor locator on this site. Return here with what's proposed and ask for input. This is probably the best resource for educating yourself available.

    As far as boiler preferences, look at the Dunkirk VLT at the bottom of the page; it's the same boiler as the Utica CSS.

    The Knight wall hung or the Triangle Tube would be my other recommendations for a mod/con. The Buderus GB142 is very easy to service and reliable, but has a cast aluminum heat exchanger.

    I'd be a little wary of any mod/con that employ's a Giannoni heat exchanger: unless you do good maintenance on both the fire and water side, it could fail prematurely.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Paul48Paul48 Member Posts: 4,492
    Heat Loss

    I'm assuming someone removed cast-iron from the first floor. The question is, did they match the amount of baseboard to the heat loss of each room?
  • polo735polo735 Member Posts: 9
    edited January 2013


    The notion that I could run a low efficiency boiler with no electricity was my own misconception. I was given that bad advice from a friend, not a contractor. Thanks for the clarification.

    Of the contractors I've met with the gentleman pitching the Buderus left me with the best impression. His company also has the best reputation.

    We are restricted because were are financing this project through a program offered by our state. We must choose a contractor from their approved list.

    The only contractor in my state shown using the feature in this website is over an hour from my home. I'll contact them but I'm not sure if they'll be willing to travel.

    What are the disadvantages of an aluminum heat exchanger?


    The cast iron radiators were removed in the 1970's when an addition was built. There is an ~1000 sqft 2 floor addition built on a slab on the back of the home. The baseboard heating was described as "old school" by some of the contractors I've had through. The heaters run the length of the exterior walls in each room. This is a 3 zone system. the original section of the house is split upstairs and downstairs. The third zone is the addition both upstairs and downstairs on one zone.
  • Paul48Paul48 Member Posts: 4,492

    How comfortable do you think running the main house as a single zone would be?
  • polo735polo735 Member Posts: 9

    I don't see a single zone in the main house being any less comfortable. I'd just prefer to separate the levels to heat only the areas being occupied.

    Truthfully most of our time will be spend in the addition which includes our master bedroom and family room. We wouldn't need to regularly heat the upstairs of the main house until we have some kids to fill up those bedrooms.
  • Paul48Paul48 Member Posts: 4,492
    High Efficiency

    Mod/cons work best, when they see a large load. The more you chop the home up into zones, the more likely you are going to have trouble keeping the boiler condensing, and that's when it's most efficient. The best way is to use an outdoor reset and let the boiler handle the whole structure.It is a totally different type of heat than conventional heat.The days of standing by a piping hot radiator to chase away a chill, after coming inside, would be gone. But the house would be warm and comfortable.Mod/cons in general do not work well with night setbacks. Keep in mind, they are attempting to provide just enough heat to offset what is being lost. If you turn the temp down to 62* at night and let the whole structure get that cold, it will take a long time to recover.These are my opinions, and some will disagree.Some will say that a boiler that they use provides answers for these situations. Just discuss your habits with the contractor, if you choose to go with a mod/con. Sizing of a mod/con is absolutely critical.
  • polo735polo735 Member Posts: 9

    I see your point about the way a mod/con boiler operates. The home has already been divided into 3 zones. This was the original homeowner's doing.

    I wouldn't have any problem heating the whole structure around the clock(in fact my wife would love this) but would this negate the cost savings?

    I assume that the load from the indirect domestic water would not be sufficient to keep the mod/con condensing?

    Thanks again for the responses
  • Paul48Paul48 Member Posts: 4,492

    I'd conservatively estimate your savings at 10-30%, over your current strategy of rotating different temps to different areas of the home. I know there's a big swing in there, but it would depend on uncontrollable variables. The indirect would not play any part in keeping the boiler condensing.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,662
    I assume that the load from the indirect domestic water would not be sufficient to keep the mod/con condensing?

    It sure would not with my setup. My house has two zones: downstairs is radiant slab at grade. Upstairs fin-tube baseboard. These zones require different temperatures and often run at different times. Boiler also runs an indirect hot water heater.

    The controller has three priorities, and the indirect runs at the highest priority. So when it is operating, the two heating zones are cut off. The boiler condenses most of the time, but not much when the indirect is running the show. The slab zone always condenses. The baseboard does as long as the house (outdoor reset) is above design temperature, but I need to run 135F water up there when it is below design temperature, and condensing is less then. If running the upstairs zone alone, the cycling is rather faster than I would prefer. Like 5 or 6 cycles per hour, bouncing off the limits.
  • polo735polo735 Member Posts: 9

    Wow I never figured that keeping my home warmer could still result in savings. That is great news.

    At this point its down to selecting the boiler. In my mind the buderus is the frontrunner. I really like, however, what I've heard/read about the triangle tube prestige. If a contractor doesn't specifically sell a brand, is it common to ask for an estimate for a specific model? Shouldn't I generally go with the boiler that the installer has the most experience with?

    From what I read, the aluminum heat exchanger can be problematic when water has less than ideal ph levels. My home has municipal water. Would this still be a issue?

    I am located in central Connecticut. Can someone recommend a hydronics guy in this area?
  • SWEISWEI Member Posts: 7,356

    while a tremendously important industrial metal, presents certain challenges when employed as heat exchanging surface.

    Triangle Tube employs 439 stainless in a very low restriction HX design.  I like it a lot.  Good company to deal with as well.

  • polo735polo735 Member Posts: 9
    Triangle Tube

    Should I feel comfortable asking a contractor for a quote on a triangle tube unit or would it be better to find someone who specializes in them? If I can't find someone in my area who will install one, is the buderus still a good option? Is there any cost difference between the two?
  • SWEISWEI Member Posts: 7,356
    Unless someone from CT jumps in here

    I'd call the rep and ask who is certified in your area.

    TT website says

    Heat Tech Associates, Inc.


    In addition to being properly trained, they get better pricing on extended warranties for residential installs.
  • Paul48Paul48 Member Posts: 4,492
    Heat Loss

    If someone tries to sell you a mod/con without doing a heat loss, show them the door. They simply do not know what they are doing.
  • polo735polo735 Member Posts: 9
    Heat Loss

    What does the heat loss calculation consist of? I want to be sure this is done by my contractor.
  • SWEISWEI Member Posts: 7,356
    they will measure

    walls, windows, doors etc.  That goes into a bit of software (often a spreadsheet) and out comes a number, hopefully room-by-room.  It's really basic math, but it works -- and a shocking number of so-called professionals still don't do them.
  • CMadatMeCMadatMe Member Posts: 3,066
    edited January 2013
    I think

    You cannot put the cart (boiler choice) before the horse (heat loss) as well as measurement of emitters for capable btu/hr output at various water temps. Experience say's you most likely will be able to run the cast iron board on a different curve then the fin tube baseboard. If that is the case I would be looking at a Viessmann Vitodens 200 with adding in the Viessmann 3-way mixing valve package. Boiler control can run two independent outdoor reset heating curves. Also carries a limited lifetime heat exchanger warranty which no other mod/con mfg offers.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
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