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condensing boilers (for old cast radiators)?

Andrew Hagen_2
Andrew Hagen_2 Member Posts: 236
The Munchkin, Knight, and Trinity share similar French made stainless steel heat exchangers. The Munchkin and Trinity are built with price as a primary concern.

The Ultra, Utica, and Buderus have aluminum heat exchangers, which worries me a little in the presence of low-pH flue gas condensate. To be fair, I have seen few failures.

The Triangle Tube Prestige has a unique stainless steel low-head-loss heat exchanger. 110MBH is the smallest size, if that is a consideration in your case.

The Viessmann Vitodens 200 and Vitodens 100 are excellent boilers. The Vitodens 100 has a different burner and control than the 200, but it has the same Viessmann-made heat exchanger. If the budget will allow, the Vitodens 200 is the best on the market. The Vitodens 100 still has the high quality Viessmann is known for, but the design has been simplified to lower the price.

The top three in my book are:

1) Vitodens 200

2) Vitodens 100 or Triangle Tube Prestige

3) Lochinvar Knight

Are you using a constant circulation control strategy and retrofitting to thermostatic radiator valves at the same time?


  • Boiling Point
    Boiling Point Member Posts: 9
    condensing boilers (for old cast radiators)?

    What should one look for in gas condensing boilers there are are alot out there, are there ones to avoid:

    some look like they might share burners or heat exchangers? price, reliability


    2.Lochinvar Knight

    3.nti trinity

    4.WM ultra


    6.Buderus gb142


    8.Triangle tube
  • Unknown
    viessmann & triangle

    I have experience with the NTI, Triangle & Viessmann.

    NTI Trinity: I wasn't very impressed with the NTI to say the least, appears like some basement inventors pet project, build quality is the pits.

    Triangle Tube Prestige: A nice solid boiler with a very unique, durable heat exchanger. someone mentioned that it was the new cast iron boiler, i'd believe it. would probably be a good choice for cast rads.

    Viessmann Vitodens: If you can afford it, its hands down the best on the market: proven high titanium stainless heat exchanger, and the most versatile and advanced control on the market. I have one it my own home for 10 months now, it does its job without fail in complete silence. it feels like one of those little robots where you can put an object in its path and it will just crawl over top or go around. it will stop at nothing to get to its goal while expending the least amount of energy doing it.

    but definitely install a sidestream filter or at the very least a strainer on the return to the boiler on a system with old rads.
  • Rick Yaun
    Rick Yaun Member Posts: 1
    CI Baseboard and Condensing Boilers.

    To answer this specific question we have designed many jobs with this application. You don't get any better than this as an application for a condensing boiler and you wind up the hero. As long as you have a full reset just set the boiler curve to match the heat loss of the structure and let it go. Dont worry about the return water temperature. Just recalculate the heatloss and make sure that the boiler can handle it at the design temperature and you are all set. The boiler can reset down and you eliminate all thermostat overshoot and undershoot. Just let the onboard computer do its job. You can wind up with 30 to 40 percent energy savings and a very comfortable evenly heated house.
    All this is predicated on the fact that the radiation was calculated correctly for the house when it was built and that you have 2pipe radiators. If not you might try an oventrop 1 port access valve. We have them available.
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