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Viessmann Vitodens 200 Combi Boiler?

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  • Viessmann Vitodens 200 Combi Boiler?

    I have yet to install a Viessmann boiler in the field, but there is a local Viessmann plant that offers Academy sessions which I plan to take this fall, however I've installed a few other brands of Mod-Cons - mostly IBC's, which are made in Vancouver, as well a a few electrics, and other gas boilers.

    I might be buying my mom's house potentially which is a 3 bed/1 bath rancher, about 1100-1200 square feet potentially, with a crawl space and I'd like to retrofit radiant floors into it in the joist spaces (coined as "staple ups," but I'd use the Radaint Heat Transfer Plates by Rehau more than likely). The house currently has about a one year old Bradford White 40 gallon electric lowboy, but I'm sure I could find a new home for it.

    I had an earlier idea to go with a simple Thermolec electric boiler for this application. But one night recently I decided to crunch the numbers with eletricity versus gas and suffice to say even with the 3rd lowest electricity rates in North America where I live, it's still pricey to heat with electricity.

    Currently where I live it's $9.78 per gigajoule (950,000 BTU's) for gas, about $16.43 per gigajoule of electricity, and if you use over 1350 kilowatts every 2 monthes, you are charged $23.00 per gigajoule for every KW over that amount (one Gigajoule = 278 kilowatts roughly). So it's 1.6 to 2.3 times as much to heat with electricity if you assume 100% efficiency with both appliances, which is not the case, as most electrics are 100% but most mod-cons are 92-95% AFUE - with even higher efficiencies in low temps. But in a nutshell it almost makes some heat pumps not seem worth it, at least a air to water version, on colder days.

    So I've dreamt up another solution - Viessmann makes a combi boiler which has a plate heat exchaner built in that modulates from 25,000 to 90,000-ish BTU's. The Boiler acts as both a boiler with a boiler supply/return, and a tankless (sort of) with the cold in/hot out through the brazed plate heat exchanger. According to the Viessmann specs, it will produce 2.1 GPM's at 128 degrees and that's with a 50 degree cold water inlet temp, which is reasonable for a 3 bed/1 bath rancher, but I have dreamt up another idea:

    What if I did a Solar Domestic preheat tank upstream of the boiler, which would bring up the inlet temp of the domestic water fed to be heated by the boiler? This would in effect increase it's output and save $$$ obviously.

    So I'm curious of a few things

    1) What can you tell me about this particular Viessmann model if you've installed it?

    2) Any thoughts about the set up I described?

    3) Any Input on the Viessmann Vitodens 100, which is about half the price, which I could use with an indirect tank?

  • #2
    Re: Viessmann Vitodens 200 Combi Boiler?

    I installed a Vitoden 100 a couple years ago with a plate exchanger built in. Very nice setup. The general contractoir supplied the unit so I have no idea what it cost. No complaint from the customer since we fired it up.

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