Been using the o’l Takagi TK-3 tankless water heater for about 2 months now and have a new perspective on these little guys. As you know, they’re not cheap, expensive actually, coming in at around $800. Then you have the learning curve in that most plumbers haven’t put many of these things in. Then you also have the joy of needing to get any type of part off of the internet or trying to find a local alternative.
The delay factor
Maybe all tankless heaters are like this or maybe it’s because my plumbers ran home-runs to all of the faucets with pex tubing (or a combo of both), but the delivery of hot-water definitely takes awhile. For larger faucets like the bathtub or shower, it happens within 10-15 seconds. For sinks, it can take up to 35 seconds. This is discouraging as you’re watching all of this nice cold water go flowing down the sink. The only way I sleep at night is by thinking about our dual flush toilets, which I hope equal out the water wasted by the tankless.
Once the water has arrived however, it’s hot for as long as you’d like. We’ve even taken showers with the washing machine or dishwasher going and have no problem. The wife can fill up the bathtub w/ hot water (huge waste) and there’s still a constant supply of hotwater for something else.
And of course, the big benefit is that you’re not heating water the other 23hrs per day that you don’t need hot water.
The required category III venting is expensive stainless steel stuff that will really set you back. This is necessary because the btu’s giving off by these units is much more than a tanked water heater. Because of the extreme temperatures/BTU’s, you can’t have anything flammable anywhere in the room. So this makes it tough for a basement where you might want to do some spray painting or something.