Critique my plumbing plan

[kazetsukai]

Originally Posted by Tejon7

Quick follow-up: the test results are in, and the ShurFlo 4008 passes city water through.

I do the same thing when hooked up to city water, running it through the pump from the hose. Be careful- too much pressure from city will blow the head off the pump.

[Rucker]

Originally Posted by Tejon7

Quick follow-up: <snip>

Just as rffffffff said, the only difference is that the pump restricts the flow rate somewhat. My test was so inaccurate and sloppy that I'm hesitant to even post the results, but here they are anyway. Please don't rely on these numbers

At 10 PSI, the pump = 1.5 GPM, hose = 2.6 GPM
At 20 PSI, the pump = 2.6 GPM, hose = 5 GPM
At 40 PSI, the pump = 5 GPM, hose = 6.6 GPM

In retrospect, this wasn't a fair test, since the hose was 5/8" diameter but the pump has 1/2" inlet and outlet. *shrug* Oh well... The take-home message for me is that the ShurFlo 4008 passes a good amount of water when it's powered off, even at fairly low pressure. I don't know if I'll end up using this "feature" in my plumbing plan, but it's good to know.

Very timely research, thanks for this!

I still think I'll interlock the shurflo and the shore water with a couple of ball valves. Maybe a three way ball valve, which I just learned is a thing.

[Tejon7]

Originally Posted by kazetsukai

I do the same thing when hooked up to city water, running it through the pump from the hose. Be careful- too much pressure from city will blow the head off the pump.

Yuck, that doesn't sound fun. It looks like regulating down to 40 psi would still give plenty of flow. That ought to be a sustainable pressure without making the pump self destruct, right?

[Tejon7]

Originally Posted by Rucker

Very timely research, thanks for this!

I still think I'll interlock the shurflo and the shore water with a couple of ball valves. Maybe a three way ball valve, which I just learned is a thing.

Glad it's of interest!

Funny, a week or two ago I found myself thinking "why don't they make ball valves with multiple outlets?". Turns out they do! Not sure if I'll end up needing a three-way, but I really like the idea. Edit: haha, I just read this again - I'm just referring three-way valves, of course!

[Danjo]

Originally Posted by Tejon7

Yuck, that doesn't sound fun. It looks like regulating down to 40 psi would still give plenty of flow. That ought to be a sustainable pressure without making the pump self destruct, right?

I put a regulator on mine (I think it’s 40 psi). My pump is fine and that’s absolutely enough pressure to run a bus

[kazetsukai]

Originally Posted by Tejon7

Yuck, that doesn't sound fun. It looks like regulating down to 40 psi would still give plenty of flow. That ought to be a sustainable pressure without making the pump self destruct, right?

Yeah, I saw a regulator in your pic. Just make sure thats in place shortly after water hookup. It also helped in my case to place a check valve right after the pump.

I don't think RV pumps actually hit 40-60PSI normally with their built-in pressure sensors/switches... When I measured at the laundry water outlet, my "60PSI" pump was pressurizing the lines to 15PSI-20PSI. Only once I replaced the pressure switch with a Square-D well pump switch was I getting 60PSI out of the pump.

There were a number of things I had to do to our water setup to get the pump to perform well.

[Tejon7]

Originally Posted by Danjo

I put a regulator on mine (I think it’s 40 psi). My pump is fine and that’s absolutely enough pressure to run a bus

I'll leave my regulator at 40 then. Good to know it's worked for you

[Tejon7]

Originally Posted by kazetsukai

Yeah, I saw a regulator in your pic. Just make sure thats in place shortly after water hookup. It also helped in my case to place a check valve right after the pump.

I don't think RV pumps actually hit 40-60PSI normally with their built-in pressure sensors/switches... When I measured at the laundry water outlet, my "60PSI" pump was pressurizing the lines to 15PSI-20PSI. Only once I replaced the pressure switch with a Square-D well pump switch was I getting 60PSI out of the pump.

There were a number of things I had to do to our water setup to get the pump to perform well.

That's good advice and good info, thank you. I think I remember seeing some of your water troubleshooting on your build thread. I'll read back through it sometime to see your pump optimizations.

[Tejon7]

It's been a while, but I wanted to post my "final" plumbing plan on this thread. I haven't installed yet, but bought all the fittings and hope to start plumbing sometime in the next month.

As before, these are just schematic drawings of the most troublesome part. Vent, strainers, accumulator tank, etc. have been omitted to keep the drawing simple and because I'm lazy.

Tank supply mode:


City water mode:


Tank Fill/Drain mode:


Suction fill mode:


I wanted to simplify things further by using 3-way valves, but couldn't find any that met my needs for a reasonable price. It's not as confusing as it looks, since I don't plan on using "Suction" mode very often and the other configurations only require opening/closing two valves. Still, I'll probably laminate these drawings and keep them with the plumbing for reference.

[flattracker]

I had written a post but when I changed pages in your thread it went away.


Since we are both doing Crowns, a couple suggestions:


In both the "old Crown" and "new Crown" I put the shower over the batteries cause there is room for the drain plumbing inboard of the batteries. I put the toilet across from the shower because there is room for plumbing under the floor. There is enough room to the right of the transmission for the holding tank, and a Propane tank. I put the generator in the old spare tire well, as there is room there. You can place a spare tire in the trunk if you want. One of my design criterion's is to not make it more difficult to maintain/repair the bus. Crowns are somewhat unique because of the engine and transmission placement. By tomorrow I will have my drain plumbing finished and I will post pictures of it.

I put in the water plumbing for the shower yesterday and it runs overhead from the right side of the bus, using pex. The water heater will be mounted behind the water closet. It is an on-demand type.
Your outside water connection fitting should have a check valve in it so you can eliminate one valve. I used one pump in the "old Crown" and it worked fine. Recirculating water in your plumbing will use energy all the time.


Even with the water heater on the opposite side of the bus, you wouldn't have to run the water long to get a hot shower.

[Rucker]

Originally Posted by Tejon7

It's been a while, but I wanted to post my "final" plumbing plan on this thread. I haven't installed yet, but bought all the fittings and hope to start plumbing sometime in the next month.

As before, these are just schematic drawings of the most troublesome part. Vent, strainers, accumulator tank, etc. have been omitted to keep the drawing simple and because I'm lazy.

Tank supply mode:
Attachment 61777

City water mode:
Attachment 61774

Tank Fill/Drain mode:
Attachment 61776

Suction fill mode:
Attachment 61775

I wanted to simplify things further by using 3-way valves, but couldn't find any that met my needs for a reasonable price. It's not as confusing as it looks, since I don't plan on using "Suction" mode very often and the other configurations only require opening/closing two valves. Still, I'll probably laminate these drawings and keep them with the plumbing for reference.

Any reason you don't put city water on the pressure side of your pump? If it's a Shurflo it has a checkvalve, and I don't know if you'll have restricted flow through the pump.

Also, is the second pump for recirc only? I think I remember you saying that you were going to do that to avoid wasting water, correct? One of your hot water taps was a distance from the water heater.

How do you avoid bleeding off all the hot water back into the freshwater tank? Momentary switch on the second pump? I'd be inclined to just run a return back to the water heater input (put a checkvalve on the cold water inlet just upstream to prevent hot water from backfeeding hot water into any fixtures.

[Tejon7]

Originally Posted by flattracker

I had written a post but when I changed pages in your thread it went away.


Since we are both doing Crowns, a couple suggestions:


In both the "old Crown" and "new Crown" I put the shower over the batteries cause there is room for the drain plumbing inboard of the batteries. I put the toilet across from the shower because there is room for plumbing under the floor. There is enough room to the right of the transmission for the holding tank, and a Propane tank. I put the generator in the old spare tire well, as there is room there. You can place a spare tire in the trunk if you want. One of my design criterion's is to not make it more difficult to maintain/repair the bus. Crowns are somewhat unique because of the engine and transmission placement. By tomorrow I will have my drain plumbing finished and I will post pictures of it.

I put in the water plumbing for the shower yesterday and it runs overhead from the right side of the bus, using pex. The water heater will be mounted behind the water closet. It is an on-demand type.
Your outside water connection fitting should have a check valve in it so you can eliminate one valve. I used one pump in the "old Crown" and it worked fine. Recirculating water in your plumbing will use energy all the time.


Even with the water heater on the opposite side of the bus, you wouldn't have to run the water long to get a hot shower.

I appreciate the layout suggestions, but at this point I'm quite a ways past the point of making any floorplan changes. Things aren't set in stone yet, but they're set in welded steel which is nearly as permanent

I am actually purposefully not using a check valve on the water inlet so that I can use that same pathway to drain the tank if needed. It does add another ball valve and another step when filling the tank, but I'm happy with the trade off.

The double pumps is on the suggestion of somebody with a working hot water recirculation system and whose advice has been 100% accurate so far. Plus I was going to have a spare on board anyway, so I might as well have it hooked up and ready to go.

The recirculation system will have a solenoid valve connected to a switch, so it will only run when needed. Only for showers, really.

[Tejon7]

Originally Posted by Rucker

Any reason you don't put city water on the pressure side of your pump? If it's a Shurflo it has a checkvalve, and I don't know if you'll have restricted flow through the pump.

Also, is the second pump for recirc only? I think I remember you saying that you were going to do that to avoid wasting water, correct? One of your hot water taps was a distance from the water heater.

How do you avoid bleeding off all the hot water back into the freshwater tank? Momentary switch on the second pump? I'd be inclined to just run a return back to the water heater input (put a checkvalve on the cold water inlet just upstream to prevent hot water from backfeeding hot water into any fixtures.

The city water before the pumps was a choice to simplify the whole setup while keeping all the same functions. I had an iteration of the plan earlier in this thread where the city water entered after the pumps and it was awfully complicated. rfffffff says that he had no problem running City water through a Shurflo 4008 and my tests verified this.

The second pump is for hor water. One for hot, one for cold. Ol Trunt uses two in his system and I'm trying to mimic his recirculation plan as much as possible.

For some reason I'm not able to conceptualize the hot water bleeding off issue that you mentioned. But just to be clear, the recirculation is not to achieve hotter water temps, it's just meant to save water when boondocking. Instead of dumping the first 7-10 seconds of shower water while waiting for the good stuff, it'll instead be recirculating back into the 100gal tank. The solenoid will also have a thermocouple that will open the valve if temps get too low (as an additional freeze prevention measure)

[flattracker]

I got to thinking about your design where you are not using a check valve in your connection to outside water. Your design appears to, under certain conditions allow for siphoning of your internal water supply into an RV park or other public water system. This is a no no. Such things are frowned upon by operators of public water systems (and can be illegal). Where I used to live in Cali the water district had an ordinance prohibiting connections of storage tanks to the water systems unless they were connected through an anti-siphoning valve.

[ol trunt]

Your plan looks good to me. Add an anti siphon valve to the campground hose bib and you're good to go.
Jack

[Rucker]

Originally Posted by Tejon7

The city water before the pumps was a choice to simplify the whole setup while keeping all the same functions. I had an iteration of the plan earlier in this thread where the city water entered after the pumps and it was awfully complicated. rfffffff says that he had no problem running City water through a Shurflo 4008 and my tests verified this.

The second pump is for hor water. One for hot, one for cold. Ol Trunt uses two in his system and I'm trying to mimic his recirculation plan as much as possible.

For some reason I'm not able to conceptualize the hot water bleeding off issue that you mentioned. But just to be clear, the recirculation is not to achieve hotter water temps, it's just meant to save water when boondocking. Instead of dumping the first 7-10 seconds of shower water while waiting for the good stuff, it'll instead be recirculating back into the 100gal tank. The solenoid will also have a thermocouple that will open the valve if temps get too low (as an additional freeze prevention measure)

The hot water bleeding off issue: How do you plan to keep from draining all your hot water back into the freshwater tank? Something like a temporary opening of a valve before taking a shower?

This is all very timely for me since I spent the last two weekends plumbing the rig and setting up the water heater. Still very much a work in process and I'm not sure my original plan is going to work.

[Tejon7]

Originally Posted by flattracker

I got to thinking about your design where you are not using a check valve in your connection to outside water. Your design appears to, under certain conditions allow for siphoning of your internal water supply into an RV park or other public water system. This is a no no. Such things are frowned upon by operators of public water systems (and can be illegal). Where I used to live in Cali the water district had an ordinance prohibiting connections of storage tanks to the water systems unless they were connected through an anti-siphoning valve.

Originally Posted by ol trunt

Your plan looks good to me. Add an anti siphon valve to the campground hose bib and you're good to go.
Jack

Problem identified and solved, all while I was out at the bus working! Thanks guys. I'll get a backflow preventer to go on the city water connection along with the prefilter and pressure regulator I already have.

[Tejon7]

Originally Posted by Rucker

The hot water bleeding off issue: How do you plan to keep from draining all your hot water back into the freshwater tank? Something like a temporary opening of a valve before taking a shower?

This is all very timely for me since I spent the last two weekends plumbing the rig and setting up the water heater. Still very much a work in process and I'm not sure my original plan is going to work.

Thanks for the clarification. I hope the following answers your question, but to be honest I expect there to be some trial and error before things work the way I want. Maybe ask again in two years when I actually know what I'm talking about?

I went with the Suburban IW60 tankless on-demand water heater, so hot water should keep going until I run out of propane or water. Just before getting in the shower, the valve for the recirculation system will open (12v solenoid valve on a switch), causing the water heater to kick on. The solenoid valve will stay open for the remainder of the shower. I plan on restricting the flow going back to the water tank to 0.5 GPM, which is the minimum the water heater needs to keep running. The heater is capable of heating 1.5 gpm up to 120° F, so the hope is that there will still be plenty of hot water for our low-flow shower head. It'll basically be like two taps are open at the same time, sharing the hot water.

This whole scheme is just for Navy showers while boondocking. If hooked up to a water source, we'll be a little less frugal with water and won't use the recirculation thingy.

[Rucker]

Originally Posted by Tejon7

Thanks for the clarification. I hope the following answers your question, but to be honest I expect there to be some trial and error before things work the way I want. Maybe ask again in two years when I actually know what I'm talking about?

I went with the Suburban IW60 tankless on-demand water heater, so hot water should keep going until I run out of propane or water. Just before getting in the shower, the valve for the recirculation system will open (12v solenoid valve on a switch), causing the water heater to kick on. The solenoid valve will stay open for the remainder of the shower. I plan on restricting the flow going back to the water tank to 0.5 GPM, which is the minimum the water heater needs to keep running. The heater is capable of heating 1.5 gpm up to 120° F, so the hope is that there will still be plenty of hot water for our low-flow shower head. It'll basically be like two taps are open at the same time, sharing the hot water.

This whole scheme is just for Navy showers while boondocking. If hooked up to a water source, we'll be a little less frugal with water and won't use the recirculation thingy.

Thanks for clarifying. I might be slightly further along than you in implementation but I've hit a few walls.

First, my Camplux 2.64 seems to take more than .5 GPM to fire up. Still trying to determine the minimum flow that kicks off the heater but it looks to be more than that. Not sure what to do if there's no adjustment and I have to blast the water just to get it to turn on.

Second, I have a recirculating pump with a 1 gallon buffer tank for recirculating hot water to avoid the initial cold water blast these units deliver.
Problem is, the water temperature in the recirculation line quickly exceeds the input temp that the water heater inlet wants to see and the device errors out. I might need to throttle down the recirculation GPM, or control it with a thermostat.

Glorious complexity.

[Tejon7]

Originally Posted by Tejon7

It's been a while, but I wanted to post my "final" plumbing plan on this thread. I haven't installed yet, but bought all the fittings and hope to start plumbing sometime in the next month.

As before, these are just schematic drawings of the most troublesome part. Vent, strainers, accumulator tank, etc. have been omitted to keep the drawing simple and because I'm lazy.

Tank supply mode:
Attachment 61777

City water mode:
Attachment 61774

Tank Fill/Drain mode:
Attachment 61776

Suction fill mode:
Attachment 61775

I wanted to simplify things further by using 3-way valves, but couldn't find any that met my needs for a reasonable price. It's not as confusing as it looks, since I don't plan on using "Suction" mode very often and the other configurations only require opening/closing two valves. Still, I'll probably laminate these drawings and keep them with the plumbing for reference.

Quoting myself here... seems a bit odd, but whatever.

Just wanted to point out a small update for anyone who finds this thread years from now. I bought all the parts for this and it was immediately clear that the triple ball valve monstrosity right next to my water tank was going to take up way too much space, leaving no room for the pumps. I did some more searching and found a Valworks brand full-port 3-way T-port valve for $80, which was much less than any I had seen before. It looks like it will fit the space much better.

If I remember, I'll do another update in 6 months or a year to report on which parts of this scheme work and which don't.