viessmann outdoor reset

Ron Schroeder_3

Consider modulating your home warming system in order to maximize your fuel economy. A mechanical engineer that I know informed me that for every 3 degrees F that a given supply temperature is lowered, 1% of fuel consumption is also lowered. It makes no economic sense to run your boiler so as to produce a fixed high heating system supply temperature throughout the year because the heat loss of your home is not constant throughout the year. Clearly, a New England Winter will require higher boiler water temperatures to maintain desired comfort levels. Spring Summer and Fall however incur much smaller heat losses. It would be advantageous to be able to take advantage of these changing seasonal differences. Our goal is to only replace the minimum amount of heat possible while maintianing those comfort levels that you have determined. The Vitorond 200 is a sectional cast iron boiler triple pass boiler that can be modulated over a narrow range with a Vitotronic 200 or 300 control. Please take care to avoid return water tempuratures that can set up a condensing environment in the combustion chamber or in the vent itself. A motorized mixing valve strategy would be helpful to continually expand the operating band width of the supply water temperature and to provide tempered return water temperature to the boiler. The Vitotronic 200 and 300 controls can provide the necessary supervision for both valve and boiler.

david_22

viessmann outdoor reset

I'm considering a proposal to upgrade my homes heating system. Nothing fancy just an old ~2400 sq ft home in New England (no radiant floors etc etc). I'll be having the Vitorond 2000 installed and I'm debating the merits of the KW10 control. I'm not opposed to spending the extra $ but I want to be confident that the return on the investment is realized in years not decades. Is there any estimates out there as to percent decline in fuel utilization when using this system?
thanks

Paul Pollets

Outdoor reset

Install the Outdoor reset control for max. energy savings. The control will lower the fuel costs and extend the life of the boiler. The Vitotronic 200 control will also manage an indirect DHW tank temperature. Systems using the indirect DHW tank have the lowest yearly fuel costs. If you're using an electric water heater or an oil-fired water heater, consider upgrading to the Indirect.

I've seen 15% to 40% reduction in fuel costs depending upon: insulation values, type of radiation, use of indirect DHW tank, etc.

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Constantin

I'd go for it..

... Outdoor reset with modulating boiler temperatures has been shown to save 9-24% in fuel per annum, IIRC, so I'd go for it. The greater the thermal mass of your system and the greater the impact of solar gain, the bigger the net benefit. So, it's less compelling in a low-mass home with baseboard and hydro-air than a concrete structure with RFH and a south-facing window-wall.

Steve Ebels_3

The Vitorond

Is an excellent medium to high temp boiler. It's able to safely digest operating temps down to the low 130-high 120* range without condensation problems. When you get the water temp down to those levels, the Vitorond will usually hit 86%+ efficiency on a combustion test. We have a 50 running that routinely hits 87% at 140* or less operating temp. No condensation in the boiler and the flue is all insulated stainless so I don't worry about that. (Speaking of flues you'll want to check out lining your chimney due to the low stack temps with this boiler.)

The point is this; with any boiler the simple physics involved dictate that the lower the water temp the boiler is firing into, the greater the efficiency. If your radiation is sized correctly, you'll find that 180+ water temps are needed very few days of any winter. Probably less than 15. The rest of the time your home will heat very nicely with water temps that allow you to take advantage of what almost any Viessmann product is designed to do. That is, operating at reduced water temps.

You are making an investment in a boiler that will last for decades given even nominal care. The return on your investment will come back two to three times or more over the life of the boiler. Even faster than that if fuel prices continue to rise the way they have in the last few years.

It wouldn't even be a question in my mind.