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Author Topic: What pipe type should I use for hot tub?  (Read 3095 times)
Kevin Warnock
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« on: July 13, 2009, 12:29:38 PM »

So my jetted tub is installed, but not hooked up. I was going to use PEX for the rest of the bus, but this jetted tub is a special situation, and I can't use PEX, to my knowledge.

The tub is just for soaking, not washing. I have a separate shower stall for that. So the tub will reuse the water, which will be stored in a dedicated 50 gallon tank under the bed. There will be a separate propane on demand water heater just for this tub. This is not a hot tub water heater, but a drinking water water heater, the same kind I have for the rest of the bus.

To take a soak, I will turn on the water faucet on the tub and hot water will flow in. The tub holds about 40 gallons with a person in it. To keep the tub warm, the water can just be turned on again, and the overflow will drain into the same tank that feeds the tub, where it will be pumped again through the on demand water heater. The user will have to manually warm up the tub on occasion, as the spout can't be left on full time or the user would get too hot.

I plan to treat the water with hot tub chemicals so it will last and be safe to use. As I understand it, I can't use PEX because PEX can't be used with treated water.

I was thinking about using conventional PVC, but that has a max temp rating of 130 degrees F. I haven't measured it, but the water heater might go over that when the system is up to temp, and 100 degree water is the input temp for the heater.

So now I am thinking about using CPVC. Does that sound like the best choice?

Separately, what hot tub chemicals should I use? I don't have a hot tub, so I'm new to this.

Finally, my water pump for this application is rated up to 250 degrees F.

Thanks
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luvrbus
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« Reply #1 on: July 13, 2009, 12:38:12 PM »

Cpvc pipe is your best  it is rated at 180 degrees at 100 psi and you will never have that, make sure to use the right cleaner and glue probably will need to go to a plumbing supply for that not a HD or Lowes    

  good luck
« Last Edit: July 13, 2009, 12:44:14 PM by luvrbus » Logged

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Nusa
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« Reply #2 on: July 13, 2009, 06:51:33 PM »

Since you're recycling water, make sure there's some kind of basic trap or filter in the drain system. Starting out clean is good, but there's no way to avoid losing human hair and dander in the water, once you get properly softened up from soaking. You don't want that stuff in your tank or lines if you can avoid it.
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RJ
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« Reply #3 on: July 13, 2009, 08:18:49 PM »

Don't have time for a full response right now, but:

Hot Tub = Spa.  Go to any pool supply store and get the necessary chemicals and test strips for a spa.  Also, do a Google search for "spa water chemistry" and/or "spa maintenance" and do your homework on how to keep the water crystal clear.  You can also get the proper glue for CPVC and PVC at the pool supply store, too.

Yes, you will need some type of filtration system (circulation pump & filter) for the HT if you plan to recycle the water.  No Excuses.  Only exception is if you drain the spa completely - not into another holding tank, but into the grey or black or sewer system.  Period.

PVC is fine for all the plumbing except coming out of the hot side of the water heater, where CPVC is better suited.  You'll only need a foot or so of CPVC.  Most spas are completely plumbed with PVC nowadays, btw.  Sweep "ells" and double 45 ells are far more energy efficient than straight 90 ells, especially in the circulation system.

Maximum water temp in a spa/HT is 104o.  You should not set your HT's water heater for more than that - it gets real dangerous to one's body real quick if you exceed 104.

That's the Cliff's Notes version, FWIW & HTH. . .

 Wink
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Kevin Warnock
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« Reply #4 on: July 13, 2009, 09:57:20 PM »

Thanks for the reminder to install a filtration system. Should I get that at a hot tub store? I looked on EBay, but didn't really know what to buy, as there are a lot of options. Does anyone here know what to buy?

Thanks for the note that spas are plumbed with PVC. The jetted tub I have is done with PVC, and the PVC is bent so there are no sharp turns. Did they heat the PVC to bend it, and then it held its shape when it cooled? That's what I would guess.

Why must I limit the temp to 104F? When I use my jetted tub in my house, I always start out much hotter than that, probably 115 or so, and then it cools down, and I put in more pure hot water. What are the health problems I might encounter from too hot water? This frankly is the first I have ever heard there is a bath temperature that is too hot. I always thought the only limit was what you could stand.

Thanks
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Nusa
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« Reply #5 on: July 13, 2009, 11:46:56 PM »

Hot tubs in this country are no longer allowed to be manufactured to be set above 104 degrees, if they want a UL listing. That doesn't mean slightly higher temperatures are going to kill you, but the risk levels increase, particularly if you couple it with booze/drugs or have health issues. Over 100 is considered dangerous for the fetus in pregnant women.

As for parts, I found this with a "hot tub filter" google. Just the first place I came across that showed a good selection to give you an idea what's out there. I have no opinion about them as a supplier: http://www.spadepot.com/shop/Filters-Filter-Parts-C187.aspx.

There are multiple choices on chemical treatments, and they aren't compatible. Chlorine and Bromine are the ones I'm familiar with, but I admit to being at least 10 years out of date on this subject. I preferred Bromine. Perhaps there is something new now?
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NewbeeMC9
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« Reply #6 on: July 14, 2009, 05:10:29 AM »

So my jetted tub is installed, but not hooked up. I was going to use PEX for the rest of the bus, but this jetted tub is a special situation, and I can't use PEX, to my knowledge.

....

so why can't PEX be used?  I've not heard such and find this interesting.  A quik google and i didn't see anything right off hand.  Would you please elaborate?


The new salt type systems are easy to use and the salt is cheap.  They are just power hogs when running.


Good luck and keep us posted with how this works out.
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luvrbus
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« Reply #7 on: July 14, 2009, 05:24:15 AM »

Newbee, the diameter of the pipe is his problem with PEX I have never seen 2 inch Pex    good luck
« Last Edit: July 14, 2009, 05:29:12 AM by luvrbus » Logged

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boogiethecat
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« Reply #8 on: July 14, 2009, 09:21:40 AM »

I took waaaay off from standard thinking and did a giant hot tub "my own way" 15 years ago, and it's been amazing. The big thing is that I use hydrogen peroxide to sterilize it (byproducts are water and oxygen) and it works astoundingly well.  All you need is 12-20 parts per million H202 in the water and you'll find it to be very wonderful.  Also, instead of using tap water, I start with distilled water and add three chemicals to make the water chemically identical to a very wonderful hotspring I know (I had the water analyzed and then paid a chemist to replicate it for me)- a dash of epsom salts, a bit of baking soda, and some calcium chloride.   I'll be happy to share the formula if you'd like.

The result? I've only had to change the water 3 times in 15 years, it stays crystal clear sky blue, there's never been even a slight hint of algae or bacteria even though it's stayed at 101 for most of those years, basically it's wonderful.  No bromine or chlorine means silky soft skin when you're done tubbing, and you can sit it it for hours on end without getting pruned.

The ONLY problem I've had with it is that I used standard PVC pipe to plumb it, and over the years with the temperature, the pipe and fittings have expanded a few thousanths to the point that they no longer stick into new fittings if I need to do a repair.  So I have to machine a few thou off of standard couplings to make things work if I have to add a fitting here or there.  But that's been the only downside of it. Otherwise, what a dream!!!

Cheers
G
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kyle4501
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« Reply #9 on: July 14, 2009, 09:56:49 AM »

The dangers of excessive temperatures in a hot tub should be common knowledge. How can your body get rid of excess heat if you are submerged in water that is at a higher temperature than your core body temp?

Immersion in water above 104-degrees Fahrenheit , especially for prolonged amounts of time, can lead to a variety of heat-related illnesses such as stroke, heart attack, nausea and brain damage. Worst case scenario, these temperatures can result in death.


. . . . . 102 is generally acceptable for almost everyone - except for infants or those who are pregnant, then the limit is 100 F for less than 10 minutes, but they should consult their doctor  Wink. . . . .


Everyone is different & YMMV.
 
« Last Edit: July 14, 2009, 09:58:24 AM by kyle4501 » Logged

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Kevin Warnock
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« Reply #10 on: July 14, 2009, 11:19:39 AM »

The reason I thought I cannot use PEX is that I've read PEX can't stand chlorine. I have assumed that there is chlorine in hot tub chemicals. I will be running just 1/2" pipe from the water heater to the tub, as my on demand water heater runs at just 1.6 gpm. Yes, I know it will take a while to fill, but I am in no hurry. Remember, this is a standard jetted bathtub, not a full size hot tub. My tub holds about 50 gallons with a person in it.

But now I hear maybe I don't need chlorine at all, so maybe PEX would work. Sure would be easier to install. Is Hydrogen Peroxide OK to use with PEX?

Boogiethecat, where did you get so much distilled water to fill a hot tub? Did you just load up half a dozen shopping carts at WalMart with gallon jugs? Since I only need 50 gallons, I would be willing to do that if it might allow me to go years between water changes. Most of the time my water will be at room temperature, though when in storage, the 'room' might well hit 100 F in the sun.



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« Reply #11 on: July 14, 2009, 11:35:18 AM »

I recommend the Swim Spa products.   It is a hydrogen peroxide based just like Boogiecat mentioned.   You also need to account for evaporation. 
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boogiethecat
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« Reply #12 on: July 14, 2009, 04:59:12 PM »

I called the local culligan man and had them deliver a tanker truck of 1000 gallons distilled water to a tank I stuck on my property.  But I've had three friends recreate my system and just buy it from the grocery store a few gallons at a time 'till they had enough.  It's pretty much a 1 time thing, all you have to replace is what evaporates and what comes out on your body (which is surprisingly a lot) as long as your filter works daily and you keep the H202 up to correct levels.  Starting with distilled is so nice because it has no guck and minerals in it and it feels SO good as compared to tap water!! (our local tap water comes with 600ppm minerals... ick... swimming pool companies recommend changing the water at 400ppm!!!)

Pex is fine with hydrogen peroxide.

  I have a metering pump and I meter 35% H202 in  as needed. But with only 50 gallons you can acheive 10-20 parts per million with H202 from the drug store with ease.
You'd want to put some in every day or two just to keep the levels right. If it's not hot it will require less.  There's a testing kit you can get to figure out what's there, but after a month it's not necessary because you will get the hang of it easily.  And if there's too much it won't hurt a thing unless you get to maybe 1000 parts per million, which would be a lot of screwing up to acheive! Then it might start to slightly bleach things but even then not much.  Remember you can gargle with 2% which is 20,000ppm...

Water formula:

to  2500 gallons distilled water add:
3780 grams baking soda (Sodium bicarbonate, NaHCO3)
225 grams  epsom salts (Magnesium Sulfate, MgSO4)
225 grams calcium chloride (CaCL2)

You can do the math to scale this to your volume...

This formula basically replicates the water (including the sterilization method) found at Harbin Hot Springs in Middletown, up by Napa Valley.  Their water is some of the best I've ever plunged my body into, and this formula feels exactly the same.
So there you go... have fun...
« Last Edit: July 14, 2009, 05:46:22 PM by boogiethecat » Logged

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Sean
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« Reply #13 on: July 14, 2009, 05:03:59 PM »

Thanks for the reminder to install a filtration system. Should I get that at a hot tub store? I looked on EBay, but didn't really know what to buy, as there are a lot of options. Does anyone here know what to buy?


In our portable hot tub setup, we have a standard household filter cartridge holder installed -- the type you would use for drinking water filtration.

I buy standard 10-micron spun paper filters for it.  Because we fill the tub with whatever water we can find, normally pumped from a lake or river, I use a fresh filter every time we fill the tub.  Filling with natural water also means treating with chemicals; we've been using sodium hypochlorite (household bleach) but are in the process of switching to standard spa-size bromine tablets in a floating brominator.

FWIW, the last time we had a "problem" with the hot tub water, wherein we both came down with "hot tub rash" (Pseudomonas Folliculitis), we had filled the darned thing with tap water (this was at the Gillette, WY fairgrounds), and we've vowed to treat with chemicals now every time, regardless of source.

I recommend you get a spa test kit as well, and test your water regularly.

-Sean
http://OurOdyssey.BlogSpot.com
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« Reply #14 on: July 15, 2009, 02:42:30 PM »

OK, so besides 1967_MCI5a and Sean, how many have or are considering hot tubs in your bus?

Just curious,

Len
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