Buying a hot tub is a significant investment. When browsing online, you will find hundreds of listings for “Wood-Fired Hot Tub for Sale,” often with very different price tags for what looks like the same product. Why does one tub cost £3,000 and another £6,000? The difference usually lies in the materials you can’t see in a thumbnail image.
Before you hand over your credit card details, you need to interrogate the specifications. A cheap tub made with poor-quality steel or uninsulated liners will end up costing you double in the long run. Use this checklist to ensure you are buying a product that will last.
1. The Steel Grade (Crucial)
The stove is the most expensive component.
AISI 304 (V2A): This is “standard” stainless steel. It is fine for fresh tap water. BUT, if you plan to use chlorine or bromine (which most people do for hygiene), this steel will corrode over time.
AISI 316 (V4A): This is the gold standard. It contains molybdenum, making it resistant to chemicals and salt. Always ask: “Is the stove 304 or 316?” If you live near the coast or want to use chemicals, Grade 316 is mandatory.
Marine Aluminium: Excellent heat conductivity (heats faster) but requires an anode to prevent corrosion.
2. The Wood Type
The cladding protects the liner and provides insulation.
Spruce: The cheapest option. It is light and knotty. It requires annual treatment (painting/oiling) to stop it rotting or turning grey.
Larch: Naturally rot-resistant due to high resin content. Very durable but heavy.
Thermowood: The best option. Heat-treated to be dimensionally stable (won’t shrink/warp) and rot-proof. It costs more but requires almost zero maintenance.
3. The Liner and Insulation
Never buy a tub without asking about insulation.
Uninsulated: Just a plastic shell in a wood box. The air gap between them sucks heat away. These cool down incredibly fast.
Insulated: Look for “closed-cell polyurethane foam” sprayed onto the shell. This acts like a thermos flask. It keeps water warm overnight and reduces wood consumption by 30-50%.
Material: Polypropylene (PP) or LDPE liners are superior to cheap fiberglass because they are flexible (won’t crack) and immune to osmosis.
4. The Included Extras
Check the “bundle.” A seemingly cheap tub might just be the shell.
The Lid: An insulated leather/vinyl cover typically costs £300-£400. Is it included? Without it, the tub is useless in winter.
The Steps: You cannot climb over a 1m high wall safely. You need wide, sturdy steps (not a ladder).
The Flue: Does it come with a rain cap and heat guard? These are safety essentials.
5. Warranty and Origin
Where is it made?
Many cheap tubs are imported from countries with lower manufacturing standards.
Check the Warranty: A 2-year warranty on the stove and liner is the minimum you should accept. Does the seller have a UK phone number? If the stove leaks in January, you want a replacement part sent from a UK warehouse, not a 6-week wait for a shipment from overseas.
Häufig gestellte Fragen (FAQ)
Is a fiberglass liner better than plastic?
Fiberglass looks glossier and more luxurious initially, but Polypropylene (plastic) is technically superior for longevity as it cannot suffer from osmosis (blistering) and is more resistant to impact.
Can I use salt water?
Only if you have an AISI 316 stove. Standard 304 steel will rust rapidly in salt water. Check the spec sheet carefully before adding salt.
How do I know if it’s insulated?
Ask for a photo of the underside or inside the cladding. You should see a thick layer of foam (usually yellow or grey). If you just see the back of the white plastic shell, it’s uninsulated.
Conclusion
When looking for a family hot tub, look beyond the price. A Thermowood tub with a 316-grade stove and foam insulation represents the best value over a 10-year lifespan. It will heat faster, look better, and survive the British weather without constant maintenance.