Welcome!

WELCOME

Welcome to the blog for our trailer hot tub build.

This project began at the beginning of April 2020, just after 'lockdown' was announced in the UK due to COVID-19. We were supposed to be touring Europe in our campervan but this obviously wasn't going to be possible... We were not allowed out to socialise or travel, so figured we needed a pretty ambitious project to keep us occupied during however many weeks we would be stuck at home.

We tried to build this for as little as possible, recycling and utilising materials left over from other projects, things hoarded in garages, donations from friends, other people's trash, innovating home-made solutions and hard work! The basic materials were an IBC tank, an old fence, a surplus trailer and some leftover decking. It was difficult to acquire materials via delivery/collection due to the lockdown, so we had to improvise a lot!

The whole project took us about 6 weeks in total, and we were working on this most days. We're fortunate in that Elliot has his own fully-equipped workshop with many many useful tools and bits and pieces so it meant we could work on the project while adhering to government rules regarding social distancing.

It is completely portable on its trailer and runs independently off a 32kw gas boiler and a 12v battery, so it can be used anywhere there is water. It is complete with water pump, seating for 2-4 people, 12v and USB chargers, LED lights and bubbles. Most importantly it has successfully kept us amused for 8 full weeks!

None of it was very planned, we had a basic idea and just ran with it. Lots of things went wrong or didn't work, and we've had SO much fun building this. (And I've learned a lot of useful DIY skills!)

This is a blog of the full build, complete with a million photos and videos. I make no apologies that this blog is very haphazard, photo and video heavy, and might not make a huge amount of sense. The primary purpose of this blog is to document this build both for our own records, and for anyone else who's interested.

We plan on towing it around Scotland when travel restrictions are relaxed enough to allow this (in our new campervan conversion... which is the next project... I'll blog about that here too) and enjoying a home-made hot tub in the most beautiful locations we can find.

Disclaimer: This is NOT meant as a tutorial. Do not try this at home. Always seek professional expert advice. Hot tub not inspected by gas-safe engineer. Appropriate PPE pretty much never worn.

Nobody died :)

FAQ!
Didn't quite anticipate this being so popular so here's some FAQ!

How long did this take to build?
About 6 weeks.

How much did it cost to build?
About £500. See here for a breakdown of costs. But bear in mind we had so much materials already, and were very fortunate in being donated a lot of materials too. We also already had a fully equipped workshop with the right tools and consumables.

Can you make me one?
Yes, we can make you one. But it will cost significantly more than this original one which as we'd have to buy all the materials we fortunately already had and of course cover our time.

How long does it take to fill/heat?

It takes about an hour to fill up 750L of water. The water is pumped into the tank via the boiler so it is 'hot filled' and ready to use at 40+ degrees as soon as it's filled. There's no waiting for it to heat up.

Where do you get the water from?

The hot tub has a hose connector so can be filled from any hose, but also comes with a built in water pump, so water can be pumped from any natural water source.

How much does it cost to run?
About £3 to initially hot-fill, and about 10p to reheat when it starts to loose temperature (after about 2 hours)

A tank of propane gas costs about £30 and we can hot-fill 750L of water about 10 times with one cylinder.

How can you tow it when full of water?!

It's not designed to be towed full of water! The idea is that we park up close to a natural water source, pump water from this, use it and drain the water back where it came from. We will only use it for a day or two at a time so there's no need for chemicals and it'll be safe to drain back to the environment.

How long does it stay warm for?

A long time! It's fully insulated but even we were surprised at how well it holds heat. When initially hot-filled at 40 degrees it will maintain hot-tub temperature for about 2 hours without the boiler. When the temperature starts to drop, the boiler can be fired up for about a minute to return it to 40+ degrees. It also retains temperature well overnight, dropping about 2 degrees.

Can I share this??

Of course, just make sure you credit back to us :) Maybe include a link back to this blog trailerhottub.blogspot.com

How are you going to keep busy now?!

We've decided to sell our campervan (eBay advert here by the way) and convert a new one. I will blog about that here

Find us on Facebook
Find us on Instagram

Monday, 20 April 2020

Trailer accessories

We made a trailer board using a bit of decking, screwing on tail lights, reflectors and number plate that we already had from another trailer directly onto this.

We also installed our new shiny chrome prop stands...

And new shiny wheels...

And the mudguards we already had hoarded...

Looking much more like a mobile hot tub now!!

Saturday, 18 April 2020

Mounting the water heater and doing some plumbing!

Cold-water-in and hot-water-out pipes were made by soldering connections onto copper pipe. The water-in pipe also got a filter installed to keep debris out of the pump/heater system.

Holes were drilled in the IBC tank and the in and out pipes were installed.

The purpose of the underside stick out valve-y bit in the plumbing system is to facilitate filling the tub using either a hose directly attached, or via the pump from any water source.

Next we made a board to mount the heater, pumps and electrics onto. We installed a galvanised steel panel behind for heat protection and to create a flue. The pipes were all connected up to the boiler and water pump.

The input for the water is connected with a hose-lock tap, so if we are near a tap or hose point it can be directly connected to this. If we're at a fresh water source, we will use the pump to pump water from the source into the tub. There is a level system to shut off this inlet when the tub is in use so the water circulates from within the tub.

Thursday, 16 April 2020

Installing the LED lights

The LED lights conveniently come with a sticky surface so these were just stuck just inside the frame onto the insulation where the hot tub will sit.

We then tested the bubbler and the lights... and WOOO they work! Disco hot tub!

Making the bubblers

The bubblers were made from copper pipe, with connections soldered onto them. We will use the air pump we've bought to pump air into these pipes and will drill tiny holes in the bubbler bars for the air to escape and produce bubbles. The copper piping is bent up into a loop to create an air lock and stop water from going into the tube and backing up into the air pump.

Aaaaand we're back in the workshop!!

Wednesday, 15 April 2020

Gas Water Heater

We had initially planned to have this hot tub wood fired via a heat exchanger coil we already had. But the option of gas-fired was also there...

Pros of wood fired:
- Free fuel as long as there's wood available
- Already have a heat exchanger
- ?More eco-friendly

Cons of wood fired
- Unable to alter the temperature of the hot water being produced
- If we run out of wood, we have to chop down a tree
- Not entirely sure how we utilise the heat exchanger to produce enough heat
- Takes hours to heat up

Pros of gas fired:
- Can easily alter the temperature
- Almost-instant hot water
- Gas easily available at most petrol stations

Cons of gas fired
- Cost of gas-fired boiler
- If we run out of gas we have to go to a petrol station

So overall it seemed more sensible and convenient to heat the water using gas, with a gas heater/boiler system.

We bought a 32kw gas-fired heater in the end.

We tested the water heater today and it successfully heats water straight from the hose to 40 odd degrees instantly!

Monday, 6 April 2020

Spending money and unboxing

We took a short pause while we ordered some materials to finish the project...

I will post a full list of the costs of the materials we used here.

We ordered a gas boiler (more info on that later...) some trailer wheels, LED lights and water and air pumps.

Attaching the cladding

Once processed, the cladding was screwed to the hot tub in alternating shades (we had some lighter wood and some darker wood).

We plan on varnishing the whole thing once it's finished to give a more 'professional' look.

At this point in the project we had to take a small break to order some materials (and spend some money!)

Processing Cladding

After much thought about what to use to clad the outside of the hot tub, and thinking about how we could do this at minimal cost... We had an old fence and lots of other leftover fence slats from other projects so figured we'd spend the time processing these.

All the screws were removed from the slats, they were planed to remove the grime and old paint, cut to size, bevel edged using a router, and sanded by hand. This made all the cladding totally free (apart from hours of labour!)

We didn't totally sand them as we quite liked the sort of 'rustic' look, and we're not worried about the screw holes being visible.

Insulating

We had some leftover insulation from another project, so this was cut to size for around the walls of the hottub. A layer of damp-proof membrane (also had some leftover from another project) was also installed to keep any moisture away from the insulation.

Affix hot tub to trailer

More wooden batons were screwed down to the decking on the trailer, and the hot tub frame was dropped into these and screwed into place to secure

And of course it had to have curvy corners...

And a bit cut out to accommodate the drain pipe..

The final screwing-down of the frame...