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Boiler advice

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Jman_3
Jman_3 Member Posts: 1
in Gas Heating
Thinking of converting from oil to gas. We have gotten estimates from several contractors, and seemed to have narrowed in down to 2 boilers. The burnham alpine, with an actual efficiency of 92.2 is much cheaper due to rebates and discounts, but our contractor is pushing us towards veissmann vitodens 200 mostly I think because of increased efficiency of 95.2. That does not seem like much of an efficiency difference. Any opinion on these boilers/companies?

Thank you

Comments

  • Tim McElwain
    Tim McElwain Member Posts: 4,621
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    Both are good choices

    each offering some different approaches to Modulating/Condensing boilers. More important is the contractor you are dealing with. Make sure he has done a heat loss on your house, has evaluated the type of emitters you have (baseboard, convectors, or radiators), can you side wall vent the boiler, how are you going to get domestic hot water and the list goes on???
  • DanLC
    DanLC Member Posts: 5
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    VP Sales & Marketing

    I'm the sales leader for US Boiler - we make the Alpine boiler. Tim is obviously correct --- first steps are application and heat load. Condensing boilers are not great for every application and your contractor should be able to advise you whether it is the best fit. Just to clear up a mis-conception, the Alpine is rated at 95% and not 92%. The industry listings are found at the AHRI website  -- look at the certification section for all listed efficiencies.
  • WoNHUSA
    WoNHUSA Member Posts: 34
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    Why not condensing?

    I have also been looking at high efficiency condensing boilers. I have spoken to several installers and gotten a few quotes for the job. One of them mentioned that a condensing boiler may not be right for my house...something about the return water not being cool enough when it gets back to the boiler, which would decrease or eliminate the condensation. But, I have only heard this from one of the contractors. How "long" of a loop does the water need to run for the temp to drop enough? Is this a problem that a homeowner even needs to consider? I know there a multiple variables for the water temp to drop, but is there a suggest loop length...in other words it sounds like I would not be able to put just the master bathroom on a loop since it is the coldest room in the house when we are burning wood.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
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    return water not being cool enough when it gets back to the boiler,

    I do not know about all systems, but in my system (mod-con boiler with radiant slab zone and a baseboard zone),  I do try for as low a return temperature I can get.



    The radiant zone is easy to get condensation because the SUPPLY temperature never exceeds 120F, so I will always get condensation. When it is over 50F outside, the supply temperature to the zone is only 76F, so I get LOTS of condensation. Even though the temperature drop through the loop seems to be less than 1F.



    For the baseboard zone, the supply temperature varies between 110F and 135F, so I always get some condensation, though not a lot when supply is 135F. Because even though this zone has LOTS of baseboard (14 feet in each of two rooms), I can use only a maximum of 6500 BTU/hour up there. So I do not get much temperature drop through that zone either.



    I think condensation is a good idea, and may get you 10% more efficiency than if you do not condense. But it seems to me that the modulation in the boiler is the big money saver. Most of the time, the outside temperature around here is above freezing. Design temperature here is 14F. So the saving is that I never fire at full rate except when running the indirect domestic hot water heater, and that is at most 1/2 hour a day. The low firing rate is what saves the most money.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,541
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    JDB

    I agree,the mod portion of mod/con is more important than condensing all the time. That being said.most fin tube applications can condense a vast majority of the time



    http://www.fcxalaska.com/PDFs/BrookhavenBaseBoard.pdf
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
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    most fin tube applications can condense a vast majority of the time

    I did not want to claim that, because I am not a heating professional and I have experience with only one heating system, the one in my house.



    My experience agrees with your claim, however. Since my supply temperature to the fin-tubed baseboard is in the range of 110F to 135F, my return temperatures must be less than these. If at the high end, when it is below design temperature outside, I get at least 5F temperature drop (and that may be the case, but I do not know because it never gets low enough to supply water that hot in normal use) my system will always condense except when it is heating the indirect water heater.



    On the other hand, if the return water temperature is 130F, while it will condense, it will not condense very much. I get best results when heating the slab, when return temperatures are always below 120F and sometimes as low as 75F. And for me, the radiant zone is the one that consumes 4x more heat than the small baseboard zone.
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