Getting hot water to a distant outdoor shower

[southernmaine]

I would like to build an outdoor shower behind our attached garage, which is the only place I could realistically build one on the property.

There is an addition between the house and garage (addition has no DHW), so I would have to exit the basement, run PEX/pvc along the outside of the addition and ultimately to the shower area. I bet it’s a good 20-25’ pex run to exit the basement and get to behind the garage.

I imagine quite a bit of heat loss in this approach, not to mention waiting for the hot water to reach the shower. Would a point-of-use propane heater (Camplux style) and hose water make more sense? I’d rather not deal with another system and tank(s) if I could tie in to our existing hot water, it’s just not conveniently located!

Expectation is summer use late May-Sept, kids and adults rinsing after beach days, etc. Also need to design this to be easy to drain for frost and freezing.

The drainage and grade behind the garage is good, no concerns about runoff or harming any structures. DHW for our house is oil-fueled hot water tank.

Appreciate any thoughts or ideas!

 

[moresnow]

Run a line off your existing system. Pex. Wrapped with the foam insulation. Set it up to be easily drainable depending on the season. Your wait for hot water won't be a be deal. I have 20' of uninsulated pex in a 50 degree or colder basement (winter) feeding a basement shower.
Save the heartache and expense of adding another independent system. My thoughts

 

[southernmaine]

Run a line off your existing system. Pex. Wrapped with the foam insulation. Set it up to be easily drainable depending on the season. Your wait for hot water won't be a be deal. I have 20' of uninsulated pex in a 50 degree or colder basement (winter) feeding a basement shower.
Save the heartache and expense of adding another independent system. My thoughts

All good points, I’ve been way overestimating heat loss. Thanks for the input, will go with the tie-in with my existing hot water.

 

[zrock]

That's not to bad of a distance probably the same distance as in most homes. a few more things i would do if you have a chance of freezing. at the lowest point and im assuming this will be your water heater install a T with another valve for winter draining that you can drain off into a bucket. Along with wrapping the pipe with foam i would wrap it with foil tape this will help keep the critters out of it, if it was me i would get some pipe that i could slide the water lines into and cap both ends then this would look nice and clean and keep the rodents away.

 

[ABMax24]

You could always do a loop in the line and add a circulator to reduce the delay to get hot water.

My Tankless NG unit has one built in, it learns the times we use hot water so it's circulated the water prior to use.

 

[gthomas785]

If it's really only 25 feet then that's no problem. When you said distant shower I was picturing like 250' across the yard which would be a different story. For such a short distance you can use 1/2" pipe and you won't even notice the wait.

 

[begreen]

All good points, I’ve been way overestimating heat loss. Thanks for the input, will go with the tie-in with my existing hot water.

We have an upstairs bathroom and a run of about 35' of insulated 3/4" copper. All interior plumbing. It takes about 3 gallons of water (~ 1.5 minutes) of running the water to get hot water at the shower. A recirc pump on the system cuts this down to about 10 seconds. The recirc pump can be wired remotely to trigger on demand.

 

[gthomas785]

We have an upstairs bathroom and a run of about 35' of insulated 3/4" copper. All interior plumbing. It takes about 3 gallons of water (~ 1.5 minutes) of running the water to get hot water at the shower. A recirc pump on the system cuts this down to about 10 seconds. The recirc pump can be wired remotely to trigger on demand.

Hmm that's odd, 35' of 3/4" pipe holds around 0.8 gallons so even if you assume the pipes' thermal mass is equal to the water (it's not) it should still take at most around 1.5 gal to fet fully hot. Maybe the pipe takes a circuitous route and is really much longer than 35'?

Anyway, this is why I always advocate 1/2" for hot water unless you really need a lot of flow. The volume of 1/2" pipe is less than half per foot of what 3/4" is and at under 50' it can usually still flow plenty of water for a shower or even filling a bathtub. Depending on your water pressure, of course.

We have a hot water run of 3/4" PEX to our kitchen that I estimated is around 100 feet altogether. It supplies the laundry and another bathroom as well, so technically 3/4" is warranted although it's rare for us to be running hot water in all three places at once. That used to mean a 4-5 minute wait for hot water at the kitchen sink, but I added a dedicated return line that reaches most of the way, along with a recirc pump that is triggered by a motion sensing switch in the kitchen. It works beautifully and did not appreciably increase our energy use for hot water.

 

[all night moe]

Any links of plumbing diagrams to this circulation pump layout and trigger on system? I have the same layout that @gthomas785 described with laundry room and bathroom prior to the kitchen sink. All with 3/4 supply line. I'm at 100' plus though.

I am/was planning on doing a tube in tube heat exchanger at the kitchen sink, heated with an OWB. The boiler system would be heated with solar for the summer months with the same approximately 500 gallons of thermal storage. I may just stick with these plans.

 

[gthomas785]

The plumbing layout is pretty simple: the pump is tied in right at the outlet of the water heater. The return line tees off of the hot water line as far away from the water heater as I could access. Comes back and there's a (1) purge drain, (2) check valve, and (3) shutoff / regulating valve before it tees back into the cold water inlet of the water heater.

I throttled down the valve so that it takes the loop about 2 minutes to come back hot. Any more flow and I'd just be wasting electricity running the pump harder than necessary.

To control the pump, I actually just plugged it into one of those wifi smart plugs. Then I bought a wifi enabled motion light switch off Amazon and just wired up the power feed to it (no load going out). Programmed in smart life app so when the motion switch turns on, the smart plug turns on. And when the motion switch times out it turns the plug off again.

If I'd had access to pull a wire from the kitchen to the basement, I probably would've just hardwired the pump into the motion sensor, seems a little more robust. But my setup works.

 

[begreen]

Anyway, this is why I always advocate 1/2" for hot water unless you really need a lot of flow. The volume of 1/2" pipe is less than half per foot of what 3/4" is and at under 50' it can usually still flow plenty of water for a shower or even filling a bathtub. Depending on your water pressure, of course.

There is a loss of head pressure in the vertical run. I have a friend that did his 2nd fl bath all in 1/2" and the water pressure is quite poor compared to the 1st floor. In our bath like his, there is a shower, toilet and sink which all have 1/2" feeds off of this 3/4" line once it is upstairs. The pressure is lower than the first floor, but totally serviceable unlike my friend's setup.

 

[all night moe]

There is a loss of head pressure in the vertical run. I have a friend that did his 2nd fl bath in 1/2" and the water pressure is quite poor compared to the 1st floor. In our bath like his, there is a shower, toilet and sink which all have 1/2" feeds off of this 3/4" line once it is upstairs. The pressure is lower than the first floor, but totally serviceable unlike my friend's setup.

My run is the same 3/4'' supply with the legs to the "appliance" necked down to 1/2''. There is very little line in 1/2''. All is located close to the 3/4'' main supply. Pressure is the same throughout the house.

 

[begreen]

Yes, all our trunk lines in the house are 3/4" with 1/2" feeds to the local fixtures.

 

[xman23]

What time you wait for hot water depends on your pressure. That said keep it simple. It's a few months a year. I would work on a easy way to drain it for the winter.