How do I get hot water to shower faster?
3220
| Posted in Energy Efficiency and Durability on
Just installed an LP tankless hot water heater. It is about 40 feet to the shower. I have 3/4″ pipe, on a well that delivers about 40PSI. Thinking about going to 1/2″ pipe for hot water supply to reduce volume that has to be heated up. I have insulated all the runs.
thanks for help.
Bruce
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Replies
Bruce,
Reducing the diameter of the tubing will help.
Moving the water heater closer will help.
Installing a second water heater -- one that just serves the shower, and is close to the shower -- will help.
Installing a tiny electric-resistance water heater -- one with a 5-gallon tank -- close to the shower, inline with the existing water heater, is another option.
Circulating pumps are sometimes used as well, but many builders report glitches when circulating pumps are used with a tankless water heater.
The following is a general comment, and not necessarily applicable to your case Bruce: tankless water heaters have been shamelessly marketed as providing 'instant' hot water and sadly many purchasers have been misled into thinking that the laws of physics do not apply in the length of time it takes for hot water to travel from source to point of use. Homeowners have often found that the delay is actually increased as the heater has needed to be moved further from point of use than a previously installed tank heater. And insulation will make little difference if there is any significant time lapse between draw instances. Water held in the pipe will cool to ambient remarkably quickly with standard levels of pipe insulation.
40' is perfect amount of water to refill modern toilet. Plumb hot to toilet, it will never sweat. use it before shower and you are getting a three fir; instant hot shower, never sweat toilet, and no wasted water, and even less water to septic or sewer, so four benefits!
think out if the box, remember the law of opposites.
(you are filling the toilet with the gallon of cold water sitting in your water line.)
AJ's solution is perfect for germ phobic people who always shower after they use the toilet. And it also works great for the opposite category--people who only flush the toilet once a day, and can schedule that in advance of a shower. The law of opposites in action! (People between those extremes may find it wastes hot water.)
I have no problem with "wasting" hot water occasionally in the toilet tank, but i would be concerned the toilet internals are not designed for water @ 140F or hotter and will degrade far more quickly leading to leaks and repairs.
1- Alan, no qualified plumber sends 140 degree water down the pipes. Tempering valves are code mandated and good practice.
2- the toilet would at max receive 100 degree water if flushed twice right away. Then the toilet itself will drop the water temperature down as it is warmed by the hot water, that is if flushed twice in a row. The hot water supply in question holds about one toilet tsnk of cold water in it's lemgth.
You're thinking "in the box" , get out sometime, tap the edge, try things,
"no qualified plumber sends 140 degree water down the pipes."
Really? Every house built here does just that.
Malcolm, read up on proper plumbing, sorry to hear you have plumbers that don't keep current with plumbing codes and best practices.
140 degree water delivered is not allowed. scalding and third degree burns in five seconds.
AJ,
That's what I get for making flip relies: You are quite right, I should keep up. The recent amendments to our plumbing code mean no fixture can release water above 49 degrees C (120.2 °F).
Unfortunately i live in a much older house where the water come out of the faucet at full temperature.
The point still holds, are toilet internals designed for 49C water. Also if it leaks someday thats a lot of wasted heat energy which i understand is eclipsing heating energy in new efficient houses
where I live heat from water and lights and tvs is heating my home much of the year, not wasted.
As far as temperature, a mixing valve could be installed that automatically keeps toilet from receiving too hot water. I install them in radiant floor systems.
At my own house I like my non water saver shower, so hot water arrives in no time. There is no need to save water here, we have too much!
"As far as temperature, a mixing valve could be installed that automatically keeps toilet from receiving too hot water. I install them in radiant floor systems."
Works for me, can you link to some good ones?
Alan, type "mixing valve" in your browser search, or call a good plumber, or fly me out to your home and I can consult for a fee. Good luck.
Honeywell thermostatic mixing valves can be set as low as 70 F. If you set it to 75 or 80 F, that would mean it would draw from the hot water pipe when both supply lines were at room temperature, and then throttle the hot water flow back to a trickle once the hot water arrived at the valve. That would minimize the heat wasted on the toilet, although it would still waste some.
In our recent whole-house remodel, I plumbed all hot water fixtures except the bath tub with 3/8" PEX to minimize the amount of hot water and time wasted waiting for heat to arrive.
Before committing to this decision I confirmed that a 100' coil of 3/8" PEX flows c. 3 GPM: shower heads and faucets will be the limiting factor in water volume, not the piping. (None of our runs are anywhere near 100' long, but once I found adequate flow at that length I didn't need to test further. In practice the flow rate in this smaller pipe will not exceed 7fps.)
3/8" PEX holds about 50% as much water per linear foot as 1/2" PEX, so I'm using about 50% less hot water each time I turn on a tap or shower & wait for heat to arrive.
I had a hard time finding manifolds and stub-out fittings for 3/8, though, so in places I used 1/2" fittings with 1/2" > 3/8" transitions between them and the pipe. A bit of extra labor and a bit of extra parts expense (and admittedly a greater number of potential leak points), but so far I'm enjoying much quicker arrival of hot water when I turn on a fixture.