schweizer
Gold Member
I can address a lot of the questions from experience in our house:
We have a Bosch propane on-demand water heater in our new house, 1.5 years old. It works great! We love it. In the first 6 months our propane use was only about 60 gallons, but we are off-the-grid and have a large propane stove/oven, gas clothes dryer, and backup propane forced-air heat, too. That seems to be great efficiency, with a 2700 sq ft house, 2 adults, 2 kids.
( One thing that probably helped our efficiency a lot is that I preheat the water first with the water coils in the woodstove which go to a heat exchanger in a 500 gallon holding tank under the house. The water in that 500 gallon tank then acts as a heat reserve to preheat water coming from the well (maybe 45 deg in winter). My goal is to feed the on-demand heater with nearly 100 deg preheated water so it only has to heat the last 20 degrees. Our experience shows that if we use water that is preheated close to the 120 deg set point of the water heater, it may cycle on/off or not start up at all. )
I haven't done the vinegar treatment to the Bosch yet, but it will be fairly easy because of the valves under the heater that the OP mentioned. We do have very hard water, and have a salt-free water softener which seems to work great for mineral deposits on the faucets.
On our heater, the air intake and exhaust are the same metal pipe -- it's a pipe within a pipe. The inner pipe is exhaust and outer is intake. The exhaust gas is quite cool because of the counter-current heat exchange principle.
Marcus
Edit: Also, we have not experienced much of the hot-cold-hot sandwich that many people worry about. All the pipes in our house are copper, so it takes a little longer to get the hot water to the right temp, but the heat stored in the metal pipes tempers the cold water that comes in-between from turning the hot water back on again.
We have a Bosch propane on-demand water heater in our new house, 1.5 years old. It works great! We love it. In the first 6 months our propane use was only about 60 gallons, but we are off-the-grid and have a large propane stove/oven, gas clothes dryer, and backup propane forced-air heat, too. That seems to be great efficiency, with a 2700 sq ft house, 2 adults, 2 kids.
( One thing that probably helped our efficiency a lot is that I preheat the water first with the water coils in the woodstove which go to a heat exchanger in a 500 gallon holding tank under the house. The water in that 500 gallon tank then acts as a heat reserve to preheat water coming from the well (maybe 45 deg in winter). My goal is to feed the on-demand heater with nearly 100 deg preheated water so it only has to heat the last 20 degrees. Our experience shows that if we use water that is preheated close to the 120 deg set point of the water heater, it may cycle on/off or not start up at all. )
I haven't done the vinegar treatment to the Bosch yet, but it will be fairly easy because of the valves under the heater that the OP mentioned. We do have very hard water, and have a salt-free water softener which seems to work great for mineral deposits on the faucets.
On our heater, the air intake and exhaust are the same metal pipe -- it's a pipe within a pipe. The inner pipe is exhaust and outer is intake. The exhaust gas is quite cool because of the counter-current heat exchange principle.
Marcus
Edit: Also, we have not experienced much of the hot-cold-hot sandwich that many people worry about. All the pipes in our house are copper, so it takes a little longer to get the hot water to the right temp, but the heat stored in the metal pipes tempers the cold water that comes in-between from turning the hot water back on again.
