Ben Langhinrinchs posted recently about his efforts at conservation. I'm a huge proponent of being as green as I can be. I have been using compact fluorescent bulbs, we replaced all the windows in our house and installed ridge vents, and we installed a high efficiency dishwasher and gas dryer.
A few years ago our aging electric water heater was dying and we needed to replace it. I was shocked to learn that it was under the house. I'm not sure why, but that's where it is. Since we live in a hurricane zone we wanted to convert to gas, and to improve efficiency we wanted to bring the water heater inside. Bringing the water heater inside meant sacrificing much-needed closet space, and we would have to run a new gas line.
In looking around for an efficient solution we came across tankless water heaters and decided they matched our lifestyle and conservation goals the best. The idea is that since they don't maintain a tank of water they are more efficient. With a tankless gas hot water heater you have a few options as far as ignition. One is to use a pilot light, which burns gas constantly. If you want a sparked ignition you have three options: electricity, battery and hydro-generated.
Since the idea was that we wanted hot water even when the power was out, which could be days or weeks in a hurricane, electric was out. We also didn't want to be dealing with changing batteries, so we opted for the hydro-generated ignition. Here's what happens: water flows through a turbine, which spins and strikes a sparker. The sparker ignites the gas, which heats the water. It's efficient, requires no maintenance, and as long as you have water and gas, you have hot water.
Installation wasn't that big a deal. It has to be vented outside and we have an old chimney from the boiler that used to be the heating system, so we tapped into that. It's in our panty, beside the dryer, which was perfect. We installed the water heater on the wall directly behind the clothes dryer, vented it out the chimney and spliced into the dryer's gas line. It's a cramped space, but since we would never have to touch it, we didn't mind.
We bought the Bosch Aquastar 1600H with an automatic ignition, and it's awful. First, if it's windy, it simply won't light. Even with a damper on the vent and a cap on the chimney there's too much wind coming down the chimney. When it's not windy it can still sometimes take 10 - 15 minutes to get the striker to finally catch. If you've had the hot water on for a while, such as when washing clothes or someone else taking a shower, the water heater stays warm enough that it won't turn back on immediately. Since it's directly behind the dryer we have the same problem if the dryer has been on, too. Finally, because the ignition is hydro-generated it shuts off the hot water if the water flow is too low. You can't have just a trickle of hot water, it has to be pretty much full force and you have to add cold water to temper it.
A tankless hot water heater is a great idea, and I love the concept. This implementation totally sucks, though. I wish we had purchased the model with the battery ignition instead, and I've contacted someone about retrofitting ours or giving us a trade in for a battery ignited unit. We paid over $500 for the heater and for that kind of money we shouldn't have to deal with this frustration. After five years of this insanity, I've had enough.