Critique my plumbing plan

[Tejon7]

I'm still a long way out from installing plumbing, but I'd like to get feedback early in case my plan has major flaws.

I'll only have a kitchen sink and shower - no additional bathroom sink or plumbed toilet. Sink needs to have hot and cold water, but I don't plan on any cold showers. Water heater will be LPG tankless, probably Girard or Precision Temp 550. I'd like a hot water recirculation system on a switch so that the shower is actually instant hot (I've been reading ol trunt posts).

Here's what I'm picturing:

That image started out really simple, then got kinda busy. I should have stuck with 2D layout, but I think you get the idea.

Any and all feedback is welcome, but I do have some specific questions.

Is it ok to have the shower plumbed with only hot water? I've never used a propane tankless water heater, but my understanding is that it's best to regulate temperature by changing flow rate instead of trying to mix hot and cold. If that's the case, do you really need a cold water line to the shower?

I don't have a gravity fill option because my floorplan has all plumbing on the passenger side. Routing the incoming water line underneath the bus from the driver's side makes my life a bit easier in the short term. Will I miss having a gravity fill option in the long term?

I wanted to put hot and cold water on separate pumps, but I don't see an easy way to switch from city to tank and back with a two-pump system. A single pump makes the change-over very straightforward - just turn off the pump. How have all of you double-pumpers out there solved this problem?

Lastly, I'm sure I've missed some valves. Where else should I have a ball valve for maintenance/winterizing/ etc.?

Thanks in advance for your (constructive) criticism!

[Iceni John]

Typical RV water pumps are intended for cold water only, and if you want to move hot water you'll need an appropriately-rated all-metal pump. The hydronic folk here probably know all about them.

[Tejon7]

Ideally, hot water will only be running back into the fresh tank for short periods. My idea of hot water recirculation is not to get the water "double hot" by running it though the heater twice. I'd just like to be able to prime the lines with hot water so that when you turn on the tap you don't get a brief surge of cold water.

My fresh tank is 100 gallons, so unless it's nearly empty, the overall temperature going through the pump shouldn't change too drastically.

[Danjo]

I’d plan on hot water to the shower since you’re already doing all the work. Your idea of what you need may change and you may sell one day and it would be in the plus column that there’s a hot water shower

[ol trunt]

I chose to set the on demand water heater at the shower temp I prefer (via a thermocouple switch at the outlet side of the heater) so I know I won't be unexpectedly blasted with scalding water. Therefore I don't use the cold water mixer when showering although I could. The water temp is sufficiently hot for washing dishes.

Here is a quote from my "Operators Manual" regarding plumbing for shore water and tank water with a two pump system.
"The bus is equipped with both shore and self- contained water systems. Two approximately 30 gallon fresh water tanks are located inside the bus over the left rear wheel. They are filled through a combined gravity fill/city
hose connect located under the slide out on the left hand side of the bus. A single ball valve located under the floor just in front of the left rear wheel drains both. A two valve manifold determines the source of the water to be supplied to the two, 12 volt water pumps which service the entire water needs of the bus. The valves are located inside at floor level behind the left rear wheel well on the side of the bus. The lower valve controls tank water and the upper valve controls shore water. Their “on” position is reflected by a horizontal positioning of either valve. Only one (or the other) water source may be used at a time. Therefore, only one valve should be in the horizontal position at any given time. INTERIOR FLOODING WILL OCCUR IF THE TANK VALVE IS LEFT OPEN WHILE SHORE WATER IS HOOKED UP AND PRESSURIZED."

.

Unfortunately the picture shows both shore and tank valves in the open position. I'll need to correct that picture. Hard to get good help when you do it yourself!

In answer to your question about double pumpers, both pumps "T" off the same line be it tank or city depending.

As far as winterizing, I have a ball cock drain for the fresh water tank under the bus and if I thought it was a real problem for me I'd add R/V antifreeze to the tank and circulate it through the system.
Jack

[Tejon7]

Originally Posted by Danjo

I’d plan on hot water to the shower since you’re already doing all the work. Your idea of what you need may change and you may sell one day and it would be in the plus column that there’s a hot water shower

I didn't explain my plan very well - I was talking about plumbing ONLY hot water to the shower. I'd set the water heater to "comfortable" temp or a bit cooler, then make slight adjustments by reducing flow rate. I don't know how well this would work - I'm kinda guessing based on what I've read about tankless heaters.

You make a valid point, though. I'm already doing 90% of the work. I might as well add a cold water line now while it's easy. So what if I rarely/never use cold water in the shower? I'm convinced - shower will now have both hot and cold water lines. Thanks for throwing cold water on my hot-headed idea

[Tejon7]

Originally Posted by ol trunt

I chose to set the on demand water heater at the shower temp I prefer (via a thermocouple switch at the outlet side of the heater) so I know I won't be unexpectedly blasted with scalding water. Therefore I don't use the cold water mixer when showering although I could. The water temp is sufficiently hot for washing dishes.

Here is a quote from my "Operators Manual" regarding plumbing for shore water and tank water with a two pump system.
"The bus is equipped with both shore and self- contained water systems. Two approximately 30 gallon fresh water tanks are located inside the bus over the left rear wheel. They are filled through a combined gravity fill/city
hose connect located under the slide out on the left hand side of the bus. A single ball valve located under the floor just in front of the left rear wheel drains both. A two valve manifold determines the source of the water to be supplied to the two, 12 volt water pumps which service the entire water needs of the bus. The valves are located inside at floor level behind the left rear wheel well on the side of the bus. The lower valve controls tank water and the upper valve controls shore water. Their “on” position is reflected by a horizontal positioning of either valve. Only one (or the other) water source may be used at a time. Therefore, only one valve should be in the horizontal position at any given time. INTERIOR FLOODING WILL OCCUR IF THE TANK VALVE IS LEFT OPEN WHILE SHORE WATER IS HOOKED UP AND PRESSURIZED."

.

Unfortunately the picture shows both shore and tank valves in the open position. I'll need to correct that picture. Hard to get good help when you do it yourself!

In answer to your question about double pumpers, both pumps "T" off the same line be it tank or city depending.

As far as winterizing, I have a ball cock drain for the fresh water tank under the bus and if I thought it was a real problem for me I'd add R/V antifreeze to the tank and circulate it through the system.
Jack

Thanks Jack. I love that you have an operators manual, and if I ever get organized I'm definitely going to do the same. Someone's going to really appreciate having that in 100 years when your bus is still on the road!

The pic and explanation are very helpful, but now I'm confused in a new way... Does city water flow through your water pumps? If so, do you just turn them off and everything works ok?

[Drew Bru]

I don't know what your intended use is (short camping trips? full time living?), but for us we used the gravity fill all the time. When our fresh water would start to run low, we'd fill some collapsible 5gal jugs with water at a public spigot and bring it back to the bus to keep the tank from running dry. Before we discovered this trick we'd have to break camp and move the bus every time we needed water.

[Tejon7]

Originally Posted by Drew Bru

I don't know what your intended use is (short camping trips? full time living?), but for us we used the gravity fill all the time. When our fresh water would start to run low, we'd fill some collapsible 5gal jugs with water at a public spigot and bring it back to the bus to keep the tank from running dry. Before we discovered this trick we'd have to break camp and move the bus every time we needed water.

Mmmmm... Yes, I can see that scenario playing out a lot for us. We'll be full timing. I know you've got a few years full-time experience, so your insight is much appreciated.

Alright, making good progress with this thread! I will amend the plan to have passenger side gravity fill and still keep the driver's-side city water connection. That complicates the build a little, but I think two different fill options on different sides of the bus will give us a lot more flexibility in the long run.

[rffffffff]

I’d have to draw a picture to explain, but if gravity fill is a problem to incorporate I made a pump loop with three valves so I can pump water into my tank from my city water line… it takes the output of the pump and redirects it into the tank from the fill line, and the pump is self priming so it’ll suck a 5 gallon jug through a 75’ hose with no issue. It’s a nice way to put water in the bus.

Also, I would recommend plumbing the vent parallel to the city water input and putting a valve on it with a screen over it. It’s good for back flushing the tank when you want to clean it so the ability to hook up a hose is nice. Having it above tank level seems like a good idea too… not sure if a below water level vent is a bad idea but I can see it siphoning or causing an issue so I would look at that.

[Tejon7]

I don't understand how this site works... I just spent 10 minutes trying to find my own thread with no luck. Finally I dug through my email junk folder to find the link.

Originally Posted by rffffffff

I’d have to draw a picture to explain, but if gravity fill is a problem to incorporate I made a pump loop with three valves so I can pump water into my tank from my city water line… it takes the output of the pump and redirects it into the tank from the fill line, and the pump is self priming so it’ll suck a 5 gallon jug through a 75’ hose with no issue. It’s a nice way to put water in the bus.

Also, I would recommend plumbing the vent parallel to the city water input and putting a valve on it with a screen over it. It’s good for back flushing the tank when you want to clean it so the ability to hook up a hose is nice. Having it above tank level seems like a good idea too… not sure if a below water level vent is a bad idea but I can see it siphoning or causing an issue so I would look at that.

I like the sound of that. Your pump must really suck - is it just a standard 12v diaphragm pump, or is that something with a little more oomph?

I think I can picture how the valve arrangement would work in my updated plan. I hope to post another draft tomorrow and get more feedback. Until then keep the suggestions coming - I'm getting a lot of good ideas here!

[rffffffff]

Yeah, shurflo 4008 I think. They can run dry and self prime. A little noisy but hard to beat.

[Tejon7]

That's fantastic. If I don't even need a special pump, then I'm definitely incorporating that idea into version 2. Do you have or wish you had a gravity fill, or does your suction technique work well enough to negate the gravity dish altogether?

I'm now convinced that I'll want a second fill option (thanks Drew Bru), but installing a gravity fill would sure be a pain, and the only place I could put it would result in a very shallow downhill angle from the fill dish to the tank top.

[rffffffff]

Originally Posted by Tejon7

That's fantastic. If I don't even need a special pump, then I'm definitely incorporating that idea into version 2. Do you have or wish you had a gravity fill, or does your suction technique work well enough to negate the gravity dish altogether?

I'm now convinced that I'll want a second fill option (thanks Drew Bru), but installing a gravity fill would sure be a pain, and the only place I could put it would result in a very shallow downhill angle from the fill dish to the tank top.

Gravity fill would be annoying, frankly. It’s way easier to leave 5 gallons on the ground with a hose in it rather than holding it up in the air. I wouldn’t do much differently if I were to do it again. I can draw my plumbing setup if it’s helpful, it’s not super complicated.

[musigenesis]

Originally Posted by Tejon7

I don't understand how this site works... I just spent 10 minutes trying to find my own thread with no luck. Finally I dug through my email junk folder to find the link.

Click on your own username to the left of any of your posts, then click "Find more posts by Tejon7" and you'll see all of your recent posts on the site, including ones on this thread.

[Tejon7]

Originally Posted by rffffffff

Gravity fill would be annoying, frankly. It’s way easier to leave 5 gallons on the ground with a hose in it rather than holding it up in the air. I wouldn’t do much differently if I were to do it again. I can draw my plumbing setup if it’s helpful, it’s not super complicated.

I'd appreciate that very much if you're willing. A sketch of a system that's been tested and works might save me from a few pitfalls.

[Tejon7]

Originally Posted by musigenesis

Click on your own username to the left of any of your posts, then click "Find more posts by Tejon7" and you'll see all of your recent posts on the site, including ones on this thread.

Got it now, thanks! I bet you never imagined that you'd end up as the unofficial skoolie.net tech advisor. "PNGs, dammit! Make your pictures PNGs!!"

[Kentucky Dreaming]

Originally Posted by Tejon7

Mmmmm... Yes, I can see that scenario playing out a lot for us. We'll be full timing. I know you've got a few years full-time experience, so your insight is much appreciated.

Alright, making good progress with this thread! I will amend the plan to have passenger side gravity fill and still keep the driver's-side city water connection. That complicates the build a little, but I think two different fill options on different sides of the bus will give us a lot more flexibility in the long run.

Not sure why you would want the gravity fill port on the passenger side. Most campsites (and RV's) are laid out with utilities on the driver side.

[Tejon7]

It's a matter of necessity - if I put in a gravity fill, it has to be on the passenger side because of my quirky layout. Reading back through this thread, I see that I didn't explain this very well. Because of a few factors, I have only one possible location to put a gravity fill that would be above the top of my fresh tank, and even then it would only be about 1" above the tank. I would have preferred to just slap a combined gravity/city inlet on the driver's side and be done, but such is life....

I'm leaning towards the driver's side combined city water/suction feed option at the moment, but if I do go with a passenger gravity dish I would still leave the city water on the driver's side.

[Kentucky Dreaming]

My truck camper is plumbed so that the fresh tank can ONLY be filled through the gravity fill port. City water port is separated from the fresh water tank and pump by a check valve. I use a Water Bandit:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

and a female to female garden hose adapter:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

to rapidly fill the tank before boondocking.