Time / Distance tankless water heater

[Mar3232]

Is there a formula for determining time / distance to receive hot water form a tankless water heater using 1/2" copper pipe? Would really like to install one just to supply 2 sinks.

Thanks.

 

[Reach4]

100 ft of type L copper pipe holds 1.21 gallons (http://www.hotwaterproducts.com/service/pipevolumecalculator.html). If your faucet at the sink flows 1.21 gpm, it would take 60 seconds for the water to get from the water heater to the faucet. 10 feet would take about 6 seconds.

Add to that the reaction time for the tankless WH to recognize the flow and to get the output water hot.

There are recirculation systems available to keep the water in the pipe hot, but only a few tankless WHs work well with those.

 

[Sponsor]

 

[hj]

plus the heat loss to heat the pipe up as the water flows through it. And the time is independent of whether it is a tank type or tankless heater.

 

[Mar3232]

I'm debating whether to get a small tank or tankless. These came up on Woot this morning and the prices are unreal but still trying to make up my mind. A small 10 gallon tank I saw only needs 1400 watts which is a real plus.

http://tools.woot.com/offers/atmor-instant-tankless-electric-water-heaters-13?ref=tg_cnt_wp_0_1

 

[Reach4]

I followed your link. The smallest in the table said 3000 watts. If there is a 1400 watt unit, it would only give about a 15F temperature rise at low flow. They do look like interesting units.

If you are going to run wire anyway, running 240 makes sense to me.

 

[Mar3232]

240 is no problem -- just kind of leary about those -- good and bad reviews but hell of a deal, one day only.