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Bosch Greenstar vs Burnham K2 Combi Units

radarlove265 Member Posts: 1
Replacing a National Radiator Company 100 series boiler original to the 1940's house. It still runs almost flawlessly. But not wanting to push my luck. From reading posts by @Steamhead it has asbestos under the jacket. Trying to figure out the abatement and removal. One quote includes it the other I'd have to go through a 3rd party.

That being said, looking for any reviews of the Bosch Greenstar combi or the Burnham K2 combi.


  • Jamie Hall
    Jamie Hall Member Posts: 23,536
    Before you look at either combi, make sure -- very sure -- that a combi will fit your requirements.

    To do that, you will need a full Manual J heat loss calculation on the house and a solid evaluation of your actual hot water requirements (both average and instantaneous). You also need to consider what type of radiators are in your house, and what water temperatures from the boiler are required to allow them to actually heat the house.

    Then you can start thinking about what boiler might fit your needs. and what water heating requirements are.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Big Ed_4
    Big Ed_4 Member Posts: 2,818
    Bosch would be my choice being a serviceman. But agree what type of radiation .. Radiator or radiant , the condensing are design for low temperature heating, the savings is when the boiler condenses ... Baseboard or air handers which is high temperature radiation, those boilers are not designed for high temperature radiation . Best off proper size boiler ...

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  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542
    Use of ODR allows for condensing for the vast majority of heating season in most cases. Modulation and extremely low mass provide savings over conventional boilers all year around.

    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • radarlove265
    radarlove265 Member Posts: 1
    Thanks for the comments. We have cast iron radiators in a modestly sized home and 2 baths though only 1 is really used. There isn't much of any insulation in the walls of the house so I presume the water can cool plenty on return. 
    Agree have relied on Bosch quality with other appliances. Though the warranty is only 5 years versus Burnham is 10