I agree with you, the point of use idea seems like it would work in this situation. It seems like the most logical answer and cost effective. Stay tuned, lets see what others reccommend. Maybe there's a better way. Thanks.

 

Wrong. Any time, material, money or thing you install to alleviate this "problem" of 3 wasted minutes of cold water will NEVER payback. 3 minutes of "wasted" water costs what, 1/2 a penny?

 

I am a big fan of circulating systems.

Crawlspace, Basement, or slab ?

 

So we run the shower for 3-5 minutes every morning till we get our hot water.

How many feet of pipe between the WH and the shower?
Is the pipe insulated?

Do you KNOW the incoming cold water temp? psi?
Do you KNOW the hot water temp?

 

To supply 1.5 GPM of 120° water with an incoming water temp of 40°, you would need an 18KW heater. That would be 75 AMPs at 240 volts. For 1 GPM you would need a 12 KW, which would be 49 amps at 240 volts.

You would be spending a lot of money just to get hot water 3 minutes quicker.

 

I would run a return line form heater....

 

A recirculating pump would be a better option. It would actually cut wasted water in entire house if done correctly.

 

I'm not sure why you would want to put a circ pump on a timer? I understand the objective would be to save money, but a 1/6 horse pump (which is all you would need) would cost about 50 or 60 bucks a year to run full time. That's not a lot of money.

 

Correct. And the other option to a timer or letting it run 24/7 is to install a thermostat (aquastat) on the recirc line so that when the pipe falls below the temp that you've set it at, the pump will kick on and then cut off when it reaches the desired temp.

 

I get a kick out of these posts about "payback" for what the OP is asking about. Who cares if the cost of whatever he does is ever paid back? It's a matter of personal comfort. Is there ever a "payback" for air conditioning a house? I think not. I put a gas tankless water heater in my house because I wanted an endless supply of hot water. At my age (65) it will never pay for itself in my lifetime. Do I care? No.

 

I get a kick out of these posts about "payback" for what the OP is asking about. Who cares if the cost of whatever he does is ever paid back?

I beg to differ. The OP referenced "3 minutes of WASTED water. Indicating to me the idea was about not wasting 3 minutes of a cold water slug until the hot water got there.

It's a matter of personal comfort.

Same here. My modis operendi for every home I've lived in is turn on the shower hot - wait for it to get hot, then add the cold to comfort level and get in. Any time or money spent on "alleviating" that "unlivable tragedy" is a waste of time and money compared to facing reality and letting sleeping dogs lie. All that could possibly be accomplished by attempting ANY of the measures available to provide instantaneous hot water at the fixture would represent far more waste. Either through heat losses in the plumbing system by recirculating, or the cost of electricity with a supplemental heater, plus installation costs and incidentals.

Is there ever a "payback" for air conditioning a house? I think not. I put a gas tankless water heater in my house because I wanted an endless supply of hot water. At my age (65) it will never pay for itself in my lifetime. Do I care? No.

 

Thanks for the info everyone. I'll try to answer some comments in the time I have.
Currently our water is cheap. So yes, we're only talking a few cents a day of wasted water. Our main issue is time. 5 minutes just feels like an eternity before coffee.
"A" frame house. We have an insulated basement/garage under the house. First floor with a cathedral ceiling and then a second floor master bedroom/bathroom balcony area. From water heater to shower is probably 50' of 3/4" and 10' of 1/2" pex. Hot water tube is only insulated for about 8' from the water heater to the garage ceiling.
As I mentioned, there seems to be a substantial heat loss from the tubing in between showers. If I wait just 5 minutes after the first shower is finished, you can feel a significant temperature drop in the water. Although it does come back up to temp on less then a minute.
To run a recirc pump full time, I think I would be doing nothing more then heating the rafters in the basement and causing our water heater to run more.
Our water pressure is 55-60 psi. Typical shower head at 2 or 2.2 gpm. So I figure a 70/30 hot/cold split, so ~1.5 gpm hot at 120 needed. Hot water probably 120 and cold around 60 (sitting in the line running through the subfloor). Temp increase required 60 deg.

To note, this issue is not solely just our showers. Our dishwasher does a horrible job. And again I think this has to do with the fact it's running cold water for 3-4 minutes while washing.

 

To note, this issue is not solely just our showers. Our dishwasher does a horrible job. And again I think this has to do with the fact it's running cold water for 3-4 minutes while washing.

So just run the hot water for a couple of minutes before starting the dishwasher, just like you'd do a shower. If the unit is due for replacement, most new ones (except maybe contractor-grade cheapos) have their own heater to get the water to 140 degrees.

 

You can install a recirc loop, that works by timer switches at the water locations.

Are you going to insulate your pipes when you move the water heater. it can help a lot.