02-03-2008, 07:00 AM
There is more to consider when deciding on a water heater than brand. I hate to make life more complicated than it already is but here are some things to think about.
You need to factor in if you already have solar hot water heating or are considering it in the future. A solar water heating system still has a water heater that is typically configured to boost the temperature of the water in the solar storage tank for those cloudy periods. That water heater has to have a modulating burner that can be adjusted to provide just the heat necessary to bring the temperature up to snuff. A non-modulating burner firing at full power could burn up the heat exchanger if the incoming water is already hot. Some manufacturers will consider the warranty void if used improperly in such an application.
The thermal efficiency of water heaters can vary greatly depending on the efficiency of the heat exchanger and whether ignition is by pilot or electronic. A unit with 10% lower efficiency burns 10% more fuel for the same heat. The price of fuel is only going in one direction in the future. It may fluctuate but the trend will only be up. Higher efficiency units cost more but what is the savings in fuel going to be over the 5-10 year (?) life expectancy of the heater? That is on top of the green aspect of burning more fuel and producing more CO2 to get your water hot.
Two of the combustion products are CO2 and H2O. Most heaters will vent the water as water vapor in the flue gas. High efficiency units capture so much of the heat that the water condenses in the lower temperature flue gas and a line must be provided to discharge the water. This water can also be slightly acidic because of NOx and SOx burn products also found in the flue gas (same reason why we have acid rain) so where/how to discharge the water could be an issue.
Bosch seems to be a company that wants to satisfy as many people as they can. They make units with modulating burners and those without. They make lower efficiency units and higher efficiency units although not as efficient as you might find with Takagi or Rinnai. Another way of saying they are middle of the road products (mediocre?).
One problem with high efficiency units is that some will not operate without electricity. Bummer not to be able to take a hot shower when the power is out. One possible solution might be to put the unit on a UPS (uninterruptable power supply) like that sold for use with computers.
Larry
You need to factor in if you already have solar hot water heating or are considering it in the future. A solar water heating system still has a water heater that is typically configured to boost the temperature of the water in the solar storage tank for those cloudy periods. That water heater has to have a modulating burner that can be adjusted to provide just the heat necessary to bring the temperature up to snuff. A non-modulating burner firing at full power could burn up the heat exchanger if the incoming water is already hot. Some manufacturers will consider the warranty void if used improperly in such an application.
The thermal efficiency of water heaters can vary greatly depending on the efficiency of the heat exchanger and whether ignition is by pilot or electronic. A unit with 10% lower efficiency burns 10% more fuel for the same heat. The price of fuel is only going in one direction in the future. It may fluctuate but the trend will only be up. Higher efficiency units cost more but what is the savings in fuel going to be over the 5-10 year (?) life expectancy of the heater? That is on top of the green aspect of burning more fuel and producing more CO2 to get your water hot.
Two of the combustion products are CO2 and H2O. Most heaters will vent the water as water vapor in the flue gas. High efficiency units capture so much of the heat that the water condenses in the lower temperature flue gas and a line must be provided to discharge the water. This water can also be slightly acidic because of NOx and SOx burn products also found in the flue gas (same reason why we have acid rain) so where/how to discharge the water could be an issue.
Bosch seems to be a company that wants to satisfy as many people as they can. They make units with modulating burners and those without. They make lower efficiency units and higher efficiency units although not as efficient as you might find with Takagi or Rinnai. Another way of saying they are middle of the road products (mediocre?).
One problem with high efficiency units is that some will not operate without electricity. Bummer not to be able to take a hot shower when the power is out. One possible solution might be to put the unit on a UPS (uninterruptable power supply) like that sold for use with computers.
Larry
Larry