I wrapped up the installation of a tankless (“on-demand”) electric hot water system for the house over the weekend. It was rather demanding of skills and time. Over a month ago i had received the first heater using a buy-it-now link on eBay. The Titan SCR4 (their beefiest model) was new so the only savings to me was the shipping was free. I spent the better part of a day removing the old electric hot water heater (which needed to be replaced) and plumbing in the connections for the unit. I also did the wiring and tried to be cheap about it and didn’t buy any additional wire (the unit comes with about 18 inches of wire for each connection) so mounted the heater very close to the electrical panel. The heater requires two double pole 40 amp breakers so a single heater will take up 4 slots of a breaker panel. Unfortunately the instructions that i followed online indicated that the heater needed only one double pole sixty amp breaker. We let water flow through for a while and then kicked on the breaker. The water only warmed a little. Despite the manufacturer’s claims that the unit was designed for “colder climates” and “large homes” we found the temperature increase inadequate for even washing dishes. We do live in Alaska and it was winter. I found instructions on installing two heaters and bought another one. I am certain that if we had used two 40 amp breakers that the heat output would have been greater.
The illustration above shows my installation. I used ample valves because i wanted the ability to remove either unit for service or warranty repair and still be able to use the remaining heater. There was quite a few hours invested in cutting pipe, soldering, and wiring. The water temperature is very nice now and i have actually turned the temperature dials on both heaters to about the middle of the range of settings. Hot water seems to arrive at the faucets and shower head faster than on the hot water tank system. The only drawback we have is that all the lights in the house have a slight flicker to them when hot water is being used. Unfortunately that includes when the toilet is flushed (which is going to have to be a future plumbing project – we don’t need warm toilet water). Seisco claims to have a system that does not cause lights to flicker.
Material list and prices:
2 Titan SCR4 heaters @ $450 each =$900
4 40 amp double pole breakers @ $21 each (only $10 each at Lowe’s) = $84
9 feet of 8/2 wire and wire nuts = $20
6 1/2 inch gate valves with compression fittings @ $10 each = $60
Copper pipe and fittings ~ $80
Over $1,140 total
A standard electric hot water heater with a tank would have cost about half that. With a life expectancy of up to 20 years (according to energystar.gov) the tankless electric heaters should last almost twice as long as the tank system. Carrying the assumption that this system will last twice as long as a tank system means that any savings in electric cost will be money in our pocket. If 15% of our electricity bill is spent on heating water and we see a 45% improvement in efficiency (see this Energy Star document) and our electric bill is $120 a month then we should see a savings of about $8 per month with this setup. If the system lasts 20 years the total savings would exceed $1,920 making the entire system more than pay for itself in our case. On top of all that it looks like the on-demand system system will qualify for a substantial tax credit for energy efficiency.
[Edit: Our additional electrical load actually caused the failure of a transformer out on the power pole outside of our house. It is advisable to contact your power company before adding service like this. They replaced the transformer and the lights didn't flicker as much when we used water. Then they increased the size of the line feeding the house from that transformer and now the lights just dim a little when you first turn the water on. We're happy with the setup for the most part now!]