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Old 03-08-2018, 04:40 PM   #1
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Plumbing Plan, Comments Appreciated

I've finished my first cut at a plumbing plan, would appreciate comments / feedback. Bus is a 40' Blue Bird All American RE being converted for full time living, family of 5.

Thanks,
Rob



Some of the components I'm looking at using:

Bladder / tanks:
http://www.skoolie.net/forums/f50/bl...nks-19652.html

Marine Water Heater (Electric / Heat Exchanger):
https://www.amazon.com/Kuuma-Water-H...ater+exchanger

Shurflo Marine Pump / Acumulator Tank:
http://shurflo.com/images/files/Mari...-4902-4212.pdf

City / Fill Inlet
https://www.amazon.com/dp/B00HTWP59S...v_ov_lig_dp_it

Drain / Grey Outlet
https://www.amazon.com/dp/B00HRX14E4...v_ov_lig_dp_it

Check Valve / Back Flow
https://www.amazon.com/dp/B000EDUTN6...v_ov_lig_dp_it

Pressure Regulator
https://www.amazon.com/dp/B003BZD08U...v_ov_lig_dp_it
https://www.amazon.com/dp/B01N7JZTYX...v_ov_lig_dp_it

Thermostatic Mixing Valve
https://www.amazon.com/dp/B01MS3X57O...v_ov_lig_dp_it

Recirculation Pump
https://www.amazon.com/dp/B0196WL6GY...v_ov_lig_dp_it

Strainer
https://www.amazon.com/Female-Strain...water+strainer
https://www.amazon.com/dp/B000F898B4...&pd_rd_w=ZZp5l
https://www.amazon.com/dp/B075PPLT3V..._t2_B0171GKS1Q
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Old 03-08-2018, 05:09 PM   #2
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Don't forget vents.
The fixture can be vented with an island/(studor) vent sized for the fixture it is serving or if you an run vent pipes for each and tie them together you can go to a bigger studor rated for the total fixture units if you can't or don't want to run a vent out the roof or sidewall up high.
The tanks also need vents.
If you don't vent the tanks then the air in the tanks can't escape as the waste is dumping in which will end up starting to show up as a slow drain because of the trapped air back pressure and will only allow you about half of the capacity of your tanks.
Then at dump time without a vent once the bakpressure is gone then you will end up with the tanks slow draining/chugging kind of like trying to pour milk,soda, or fuel out of a container to fast.
The tanks need to breath in and out.
In theory the studor vents should work for draining the tanks because there real specification name is AAV air admittance valve which allows air in but they won't help on the filling issue of trapped air because they won't allow air out.
Didn't really study your plan yet?
Just breezed through to look for vents?
The tank vents I never even thought about until someone else here 3-4 years ago brought it up when I was talking about my plumbing.
Good luck
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Old 03-08-2018, 06:03 PM   #3
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Quote:
Originally Posted by Jolly Roger bus 223 View Post
Don't forget vents.
The fixture can be vented with an island/(studor) vent sized for the fixture it is serving or if you an run vent pipes for each and tie them together you can go to a bigger studor rated for the total fixture units if you can't or don't want to run a vent out the roof or sidewall up high.
The tanks also need vents.
If you don't vent the tanks then the air in the tanks can't escape as the waste is dumping in which will end up starting to show up as a slow drain because of the trapped air back pressure and will only allow you about half of the capacity of your tanks.
Then at dump time without a vent once the bakpressure is gone then you will end up with the tanks slow draining/chugging kind of like trying to pour milk,soda, or fuel out of a container to fast.
The tanks need to breath in and out.
In theory the studor vents should work for draining the tanks because there real specification name is AAV air admittance valve which allows air in but they won't help on the filling issue of trapped air because they won't allow air out.
Didn't really study your plan yet?
Just breezed through to look for vents?
The tank vents I never even thought about until someone else here 3-4 years ago brought it up when I was talking about my plumbing.
Good luck
Vents are very important...I add that the AAVs need to be as close to ceiling as possible...above the highest water outlet



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Old 03-08-2018, 06:54 PM   #4
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Thanks guys, appreciate the comments. Plumbing is definitely not my strong suit.

I'm excited to hear about the AAVs, I was really hoping not to have to run a roof vent. There is currently one drain vent shown at the top right of the grey water line, but wasn't really sure where to put it.

This is kind of interesting:
https://www.studor.net/trap-vent

The way we've laid things out, all 3 fixtures will be within 6' or so with the drain sloping down from the sink, to the washer standpipe, to the tub drain below the floor. So you think it's necessary to put an AAV on each, or just at the top end by the sink? Otherwise we could probably extend a vent pipe up past the washer standpipe and put a normal AAV on the top, and/or another trap vent below the tub?

Tank vents is an interesting one. We are going to try using bladders contained in a non-sealed tank. In theory the bladders don't need to be vented as they expand and contract with the water and so have very little air in them once the system is bled. I'm still waiting to see how that works out. My plan is to add vents on the right side by the gravity fill / grey flush connections if we seem to have issues? The bladders only have two connections, one toward the top and one toward the bottom. Pressurized fill can be from either, drain from bottom, gravity fill from top. The bladders are not pressurized unless overfilled, more like an air mattress than a balloon I suppose.

Thanks,
Rob
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Old 03-08-2018, 07:15 PM   #5
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RV water systems are pressurized and don't need a vent beyond the pump.

Freshwater tanks (behind the pump) are usually vented with a small-bore tube right back to the fill point. Grey water tanks are simply vented under the unit.

The only time you need a roof vent is if you have a black tank, to get the smell up and away. The reason the black tank needs venting it that if it gets warm, and pressurizes, you could have a nasty experience when you open the toilet valve.
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Old 03-08-2018, 09:31 PM   #6
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Look at the Hepvo trap for your sink drain. It's a waterless trap so you don't need the studor vent and it also makes winterizing easier.

When using a wet P trap the studor vent is necessary to keep the drain line from siphoning the trap. Another way to avoid AAV's is to make your drain line a larger diameter so drain water never fills the drain pipe and creates a suction in the pipe. As long as air can move around in the drain your traps won't get sucked dry.
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Old 03-15-2018, 05:48 AM   #7
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Are you planning on adding a water filtration system?

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Old 03-25-2018, 05:31 PM   #8
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We’ll probably use an inline filter on the hose when filling the tank. Drinking and cooking water will be filtered in a Berkey.



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Old 03-25-2018, 05:46 PM   #9
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Quote:
Originally Posted by roach711 View Post
Look at the Hepvo trap for your sink drain. It's a waterless trap so you don't need the studor vent and it also makes winterizing easier.

When using a wet P trap the studor vent is necessary to keep the drain line from siphoning the trap. Another way to avoid AAV's is to make your drain line a larger diameter so drain water never fills the drain pipe and creates a suction in the pipe. As long as air can move around in the drain your traps won't get sucked dry.
The problem with vents is that they are always open, and will sometimes smell. The only way to deal with that is to raise them high, and that's way too much trouble.

So yeah, the traps will siphon when you drain the grey tank. Deal with it by pouring a glass of water into the sink and shower when the job is done.
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Old 04-01-2018, 10:29 PM   #10
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nice drawing! It would be a good idea to have identical pumps, If one fails it won't leave you totally stranded. I would pick the most common pump that Homedepot or Lowes sells. Those bladder bags makes me nervous.
Best of luck.~Dilly
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Old 04-01-2018, 10:56 PM   #11
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The problem with vents is that they are always open, and will sometimes smell. The only way to deal with that is to raise them high, and that's way too much trouble.

So yeah, the traps will siphon when you drain the grey tank. Deal with it by pouring a glass of water into the sink and shower when the job is done.
A traditional vent stack is always open but the studor and hepvo vents seal after the water drains. No stink with those two.

If you put a small diameter vent on the grey tank your P traps won't be siphoned. My tank vent is a piece of 3/8" tubing with some screening over the end to keep bugs out.
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Old 04-02-2018, 09:34 PM   #12
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Thanks for making this diagram. It's very helpful.

I am completely inexperienced with plumbing, so I'm going to ask some dumb questions:
1. To go from fresh water tanks to city direct water, you'd close valve 3, open valve 2, and flip the breaker to turn off the recirculating pump, correct? Then, do the opposite when you unhook from city water, right?

2. How do you turn on/off recirculation? Is it flipping a circuit breaker to turn that pump on/off and crawling under the bus to open/close valve 7?

3. If the recirculating pump is on, wouldn't the "cold" side of the faucets also get some hot water?

4. The kuuma water heater only needs electricity (1500 watts) when the webasto is off, right? Otherwise it just works as a heat exchanger from the hot coolant off the webasto? So, the circuit breaker for this is somethibg else you need to turn on/off when connecting to shore power so you dont drain your batteries?

Thanks for bearing with me. I'm excited to hear how the install goes.
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Old 04-02-2018, 10:09 PM   #13
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1) In the drawing you'll see a one way check valve between the tank and the fixtures. The city water inlet comes in downstream of the check valve so when the system is hooked up to city water the tank doesn't get backfilled. No need to close/open valves.

2) The Shurflo pumps typically have a pressure sensor that switches the pump on when water pressure drops when a faucet opens. So no need to switch the pump off.

3) Not sure what the recirc pump is for, but as drawn it would feed hot water back into the cold water line. A house with a long run from the hot water heater to the faucets may use a recirc pump to avoid long waits for hot water to the faucet. A bus doesn't have a long hot water run and shouldn't need a recirc pump.

4) There is typically a wall switch to turn the water heater on/off, but using the breaker would work.
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Old 04-02-2018, 10:59 PM   #14
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1) In the drawing you'll see a one way check valve between the tank and the fixtures. The city water inlet comes in downstream of the check valve so when the system is hooked up to city water the tank doesn't get backfilled. No need to close/open valves.
Thanks for helping me understand.
If both valves 2 and 3 are open and the circulating pump is running, wouldn't some water run the wrong way through valve 2? It looks to me like it needs one more check valve.
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Old 04-03-2018, 05:17 AM   #15
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Looking good Rob!

I have no experience with a bladder for a grey holding tank but I'm not so sure that is going to work very well (it certainly DOES work for fresh water). The "pressure" aspect is what bothers me. Hope I'm wrong. I have no idea how that will affect the venting but I'm a big fan of TWO roof mounted vents for each "bad" holding tank. This allows air to circulate. When using one of the vents that generates a tiny bit of vacuum (like the Cyclone), this prevents bad air from entering the home when the toilet is flushed (which you don't have). Grey tank air can stink every bit as much as black tank air.

Not sure it was answered but a single AAV somewhere in the line should be sufficient as you have described it.
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Old 04-03-2018, 02:24 PM   #16
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Thanks for helping me understand.
If both valves 2 and 3 are open and the circulating pump is running, wouldn't some water run the wrong way through valve 2? It looks to me like it needs one more check valve.
The city water inlet typically has a check valve built in. Good catch!
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Old 04-03-2018, 02:44 PM   #17
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The city water inlet typically has a check valve built in. Good catch!
thanks, but I'm asking about a different area. It looks like there needs to be a check valve right next to Ball Valve 2. Otherwise, when the pump turns on, some portion of the water will make a circle over and over again going the "wrong way" through valve 2 back the "right way" through the pump, "wrong way" through valve 2, etc.

This will result in less water pressure at the sink, etc.
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Old 04-03-2018, 03:46 PM   #18
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thanks, but I'm asking about a different area. It looks like there needs to be a check valve right next to Ball Valve 2. Otherwise, when the pump turns on, some portion of the water will make a circle over and over again going the "wrong way" through valve 2 back the "right way" through the pump, "wrong way" through valve 2, etc.

This will result in less water pressure at the sink, etc.
You're right about that, but to keep it simple the city water wouldn't normally be plumbed in like it is in the drawing. My clean water tank has three threaded holes in the end of the tank; one up at the top and two down at the bottom. I use the top as my gravity feed/vent. One of the bottom holes goes to the inlet of the pump and the other goes to a drain. The city water hose goes directly from the inlet fitting on the body directly to the pressure side of the water pump with no shutoff valve necessary. There's no reason to have the city water line and the pump inlet line connected except for filling the tank and the gravity fill works fine for that.

Of course it all depends on what your plan is for your bus. We weekend warriors are happy with basic creature comforts while the full timers want a house on wheels. No wrong answer here. Just a matter of how much money you want to throw at it.
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Old 04-03-2018, 04:40 PM   #19
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I thought I had put this in there somewhere, but it doesn't look like it. Sorry.

My intention is to set the manifold valves manually when connecting/disconnecting to city water. Filling the bladder is a little different as it doesn't have a true gravity feed port like a normal tank. Just two hose connections on the end; one toward the bottom, one toward the top.

- When running self contained valves 3 and 4 would be open, 2 would be closed.

- When running on city water valves 3 and 4 would be closed, 2 would be open.

- When filling the tank from city water 2 and 3 would be closed, 4 and 5 would be open (5 functioning as overflow protection for the bladder).

- When gravity filling the tank 2, 3 and 4 would all be closed, with only 5 open. We don't normally plan to fill this way, but want to have it as a backup option.

The main pump will be on a switch and only turned on when needed (when using water off grid). The circulation pump is to keep from wasting water while waiting for the hot to get from the tank to the tap. It's not strictly necessary, but even if we only have 10' of line that's about 1/4 gallon wasted every time you turn the tap on. For a cheap $20 pump and an extra bit of PEX it seemed worth doing. Generally the requirements for the recirculation pump are much less than that of the main pump, it just needs to be able to move water around the loop at pressure, not create the primary pressure / flow.

In home installs the circulation pump is often on a timer so it's always ready. That would end up wasting power in a bus. I'm just going to put it on a manual switch so you run it for a minute or two before using the hot water. I have a dual pressure / temperature gauge I was thinking of putting at the end of the line near the circulation pump so you can flip the switch and just watch the temperature gauge to know when the hot water gets there. Yes this does feed some warm water back into the cold side. Ideally this just gets sucked back into the hot water heater, but not really a big deal if not all of it does.

Valves 6 and 7 are just there so we can isolate the hot water loop or the recirculating loop in case there is a problem. From that perspective it might be smart to add another valve (or check valve) on the outlet end of the recirculating loop so it can be completely isolated. Ideally the recirculation outlet will probably tap into the cold supply between the accumulator and the water heater. That way it will hopefully satisfy the demand of the water heater directly without the main pump turning on. The accumulator should help buffer it a bit against mismatch.

Probably overkill but I'm running 3/4" brass for the manifold, 3/4" PEX for the mainlines, and 1/2" PEX for the branches. The water tanks, pump, accumulator, water heater and manifold (valves 1-4) will all be located in the storage bins under the bus. The fresh water inlet, and grey water outlet will be plumbed out to the side of the bus. The overflow, gravity fill, and grey water flush will all just be garden hose connections inside the storage bin.
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Old 04-03-2018, 05:35 PM   #20
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Quote:
Originally Posted by Biscuitsjam View Post
Thanks for making this diagram. It's very helpful.

I am completely inexperienced with plumbing, so I'm going to ask some dumb questions:
1. To go from fresh water tanks to city direct water, you'd close valve 3, open valve 2, and flip the breaker to turn off the recirculating pump, correct? Then, do the opposite when you unhook from city water, right?

2. How do you turn on/off recirculation? Is it flipping a circuit breaker to turn that pump on/off and crawling under the bus to open/close valve 7?

3. If the recirculating pump is on, wouldn't the "cold" side of the faucets also get some hot water?

4. The kuuma water heater only needs electricity (1500 watts) when the webasto is off, right? Otherwise it just works as a heat exchanger from the hot coolant off the webasto? So, the circuit breaker for this is somethibg else you need to turn on/off when connecting to shore power so you dont drain your batteries?

Thanks for bearing with me. I'm excited to hear how the install goes.
Hopefully my last comment clears some of these up.

1. That's basically right, see the post above for details. Only additional detail is also needing to open / close valve 4 to isolate the water tank when on city water but not filling the tank. The main pump (following valve 3) turns on automatically when the pressure at it's outlet falls below a preset minimum. The accumulator uses a pressurized air bladder to maintain water pressure for a bit so the pump doesn't have to turn on every time a tap is opened even briefly. There will also be a switch inside the bus to cut power to the main pump when it's not needed, like when on city water.

2. Valve 7 is inside the bus and stays open all the time, unless there's a leak or some other problem with the recirculation loop. The recirculation pump (following valve 7) is only run when you want to flush cold water out of the hot water lines without wasting any water. The recirculation pump will be inside the bus and powered by a conveniently located switch. Ideally there will be a temperature gauge so you know when the cold water has been flushed out of the line.

3. Yes, that can happen. Ideally most of the warm water being pumped back into the cold side will be taken up by the water heater drawing in cold water to replace the hot being drawn out. And if the lengths of the hot water line and recirculation return are about the same then most of it may just stay in the recirculation return line. But depending on what else is going on, some of that warm water can end up in the cold supply line.

4. Correct. We ended up going with the Whale Seaward model linked below, but same idea. We will only turn on power to the electric heating element when we want to spend electricity to heat water. Ideally we'll do that after the battery is topped up and we have surplus solar power available, making the hot water tank another storage mechanism for the solar. But sometimes we may decide to use battery power to heat it up.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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