tankless water heater questions
brad7945
| Posted in Energy, Heating & Insulation on
I have a kitchen sink with a hot water line nearly 50 ft from the basement water heater. Takes about 3 gallons to get hot. I am researching ‘point of use’ heaters to place in the floor joist below the sink. Wondering if anyone has experience in this area to make an informal recommendation.
I have looked at the Insinkerator W152/154, and the Stiebel Eltron tank and tankless units. In any of these models, do I assume that I am connecting to a cold water line? Or can they be used to supplement the hot water line?
Thanks in advance.
Replies
If you make a 1/2" pex home run directly to your hot water heater my quick math comes up with 1/2 gal of water over 50'. 6x faster response time and you don't have to run a new 10-2 wire to the undercab heater.
edit: math is 3.14 x .25" x .25" x 50' x 12"/1' =116 cubic inches Plugged into an online converter to get .502 gallons
Beer was created so carpenters wouldn't rule the world.
Edited 12/1/2009 3:05 pm ET by IdahoDon
What about running a 1/2" return line back to the WH with a small pump and turn it into a continous circulating loop? The net result is instant hot water at that sink.
"What about running a 1/2" return line back to the WH with a small pump and turn it into a continous circulating loop? The net result is instant hot water at that sink"
And a water heater that cycles on more often and electric used by the pump and additional heat to overcome in the summer as it disapates from the line between the wh and sink
There are recirc systems that will only recirc when you turn on the tap and won't give you water until it trips the temp sensor in the unit. Saves all of the above.
Edited 12/2/2009 12:37 pm ET by cussnu2
I have a Stiebel Eltron DHC-E10 under my kitchen sink. I replaced a Eemax, which had a loud relay and too high a flow requirement. It was hard to control the temperature. The Stiebel Eltron is far superior and worth the extra $100. I have well water that is cold in the winter (60°F) and hot in the summer (80°F). It can't make much hot water when the input water is cold. I have to set it to just a trickle to fill up the bathtub. It can't self regulate to maintain a minimum temperature. High flow is necessarily going to be heated less. But it does have a thermostat for maximum temperature. If you hooked it to your hot water supply I'm pretty sure it will turn off the heater element when the input water is hot already.
The 50 amp breaker and the 8 gauge wire you have to run to it may be non-trivial. Mine is only about 6 feet from the breaker panel and I planned for it from the start. Even so the voltage in the house drops whenever the water heater comes on. I can tell by listening to appliances that are running, like the refrigerator fan or the microwave. I keep my important computers on voltage conditioners.
Grundfos Comfort System. A retrofit recirculating system, works great, no return line needed.
wookie
Thanks for the tip. I remember reading about this about a year ago. Do you happen to know if its possible to use PEX as that return line from the furthest tap?
You do not need a return line. Go to the Grundfos website and check the Comfort System out. It works and is very reliable.
If you chose a system that requires a return line, Uponor would be my choice as far as Pex.
wookie
The Grundfos Comfort System gets my vote, too.
I don't have facts to back this, but I believe it would probably be the cheapest to operate since it circulates only at the times you set and only when the temperature drops low enough.
The first time I saw one was on a final plumbing inspection, and I wrote the plumber up for having failed to install a recirc lne. Embarrassing, but he accepted my apology graciously after he explained how it works.