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Setting up a hot tub while boondocking in the forest


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We own a piece of rural property in the mountains, which is completely off grid. We have a new trailer on the property with solar panels, 500-amps of lithium batteries as well as a large generator. The trailer is permanently set in its location.

We're thinking about putting a hot tub close to the trailer but have some considerations to contend with. Hopefully some experienced folks can help shed some light on what's doable and what's not.

1. We're looking at a 3-4 person hot tub that would run at 20-amp / 110-volts. It would be plugged into our generator, which has 20-amp outlets. I understand these types of hot tubs come with roughly a 12' power cable, but our generator is about 35' away from where we'd setup the hot tub. From what I gather you're not supposed to use an extension cord, however we'd have to anyway. I can get a 25' 12-awg/3 extension cord, would that work for that long of a run?

2. Since the hot tub would be off when we're not there, which is every couple of weeks I'm concerned about water filtration. I could add a pond pump to the hot tub and connect that to the trailer to run 24/7 as those are low wattage. Would that circulation prevent the water from being stagnant? Obviously I can run the hot tub's filter when we're there.

3. Based on our situation and you can even say limited use, what would be realistic water change intervals?

4. How long should we expect a hot tub based one what I've described here to heat up?

Thanks in advance for any input I can get.

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1. Extension cords are discouraged because they are usually not 12awg, but 16 or 18, and can't carry the load. A #12 cord will be fine, but it would be cheaper to run a little conduit and put in a plug nearer the location.

2. Technically, spa water is stagnant in fresh water terms. You want circulation for filtration and chemical dispersion, and a pond pump will only move around the tub water, leaving the pipes free to grow nasties. It's better than nothing, but not a replacement for running the spa.

3. Since it will be off when you aren't there, I'd say often. 

4. 0-3 degrees per hour, depending on ambient temp.

What mountains? Freezing is a big concern in your situation.

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We're at around 2,100' in elevation, we rarely get freezing temps for more that 12 hours, but it is something to consider.

How do you think people with wood burning hot tubs contend with the water when not in use? I think they need to be kept filled to prevent the wood from drying and cracking. Obviously there's no circulation and I don't even know if you can use chemicals in those.

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43 minutes ago, Cusser said:

I guess I've read that 110V spas need to heat quite a few hours per day.  If so, won't that generator be running a lot?

You're right and I think that might be one of the drawbacks to doing this. Even if I did turn it off it would take too long to heat up. I think my only possible option is like the AquaRest 300 that is a 2-person 160 gals. Still have more research to do.

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There are wood hot tubs, and there are wood burning heaters. I've worked on a few wood tubs, some were still slats, and they leak if they dry out but seal up once the wood swells, and one with a liner. I've only seen wood burning heaters on tv and in ads.

You must use chemicals in any hot tub. Which you use can vary, but they all need sanitizer and ph adjusters. I have no idea how they maintain a wood burning spa.

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5 minutes ago, Brad204 said:

Would getting a propane heater and a big tank be something to think about?

1) Would heat up much faster

2) silent compared to running the generator

3) I assume would burn less fuel.

We have a 300-gal propane tank but it might be a little too far of a run (50') from where the hot tub would be setup. I didn't know they made propane hot tubs.

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@Floating Away What about a propane on demand tankless water heater. Recirculate the water from the spa back into the spa. It will get the water hot quicker than waiting for the 1KW element that is normally used in 110V spas (36+ hours from fill) and then when the water is hot let the spa take over. Run both heaters at same time and save even more time. When away run the small battery pump shown off the solar and plumb a filter inline apart from the spa or even plumb it into the spa plumbing and circulate like a circ pump through the spas filters. Won't solve all the problems but might get you close.

Model shown Runs on 2 D batteries

Camplux, Eccoflo, Tankless Water Heater

You might also consider a "salt cell" Like a Saltron mini (never used one) might help keep water sanitized while away.  6' power cord; 120 VAC, 0.2A. 12' cell cable; output: 5 VDC.

https://www.spadepot.com/Saltron-Mini-Spa-Salt-Water-System-Chlorine-Generator-P2457

 

@RDspaguy Thoughts?

 

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Yesterday I was watching an episode of Homestead Rescue (Season 7 Episode 3 I believe) - and they were actually setting up an old off-the-grid Alaskan hot tub using a teakwood round tub, with a wall divider and a "snorkel" fire burning stove (basically a metal box with a tall chimney stack and an air inlet to regulate fire).

You can watch the full episode but from what I gather, they leave the teakwood tub empty and dry most of the year, then clean it thoroughly when ready for use, and fill with water (the wood swells up and becomes water tight again after filled with water).   The stove box sits in the water and there's a divider wall between it and the sitting area of the tub.   The fire box has an air intake and a tall chimney stove to heat up the water.  

They didn't use jets, but I'm sure you could easily add a cheap/simple 110V spa-pack with a low power pump and some jets if you really wanted to go that route. 

 

Also, my brother-in-law in europe also has a hybrid hot tub which plugs into an outlet to run the jets, but uses a wood burning stove on the side to heat the water - but I don't know what brand they are or if they're sold in the USA.

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First off, I appreciate everyone's input, it's been very helpful.

Since filtration is one of my primary concerns I wondered how wood burning hot tubs deal with filtration. So I called a manufacturer this morning and talked to them about it. What I was told with the wood burning hot tubs you'd want to drain them and refill them weekly. Since we don't have easy access to water that rules out those types of hot tubs.

I think my only realistic option would have been an Aquarest 300. I spoke to an owner of one and he said it runs for about 3 hours a day during the summer and 12 hours a day during the winter. I don't think my solar system would be able to run that during the winter. The other consideration is the long heat up time, which is 15-hours plus.

So for our limited use and resource this just isn't going to work. But it was totally worth investigating and I learned a lot on the way.

 

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On 6/27/2022 at 4:07 PM, CanadianSpaTech said:

Thoughts

Those heaters don't have thermostats, and will heat anytime water is flowing. Using a thermostat controlled pump would cause boil-out from residual heat in the heat exchanger when flow stopped. I used one just like that on my smoker trailer and had to wire in a switch to turn it off and let the water run for a few minutes to cool the exchanger. I melted my pvc on the first set-up and ran copper with a pressure relief valve next.

They are also impossible to winterize. I had my first one freeze in spite of being blown out. Now I bring it inside for winter.

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