Boaters warned of dehumidifier fire risk

Laura Hodgetts

Following a blaze on a Sadler 29, boaters are being warned of the risks of a dehumidifier fire risk and are being urged to make regular checks

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Boat owners attempting to battle winter damp aboard their yachts are urged to use desiccant rather than compressor dehumidifiers and to maintain and monitor units to minimise fire risks.

Yacht Havens marina group has issued safety guidance to its berth and mooring holders following a blaze at one of its sites, which destroyed the interior and damaged decking on a Sadler 29.

A spokesman said: “A recent investigation into a boat fire at one of our Yacht Havens discovered that a domestic compressor dehumidifier had been set up to drain permanently into the bilge. The coils within the dehumidifier froze and subsequently overheated.

“A Sadler 29 was written off. It was predominantly internal damage, rather than structural, but the fire damaged large parts of the decking too.”

Insurers often require dehumidifiers to be rated for marine use as a condition of cover.

Matt Elliott, the chief engineer at Meaco, an international seller of both desiccant and compressor dehumidifiers for ‘domestic use’ – the type primarily used on boats – urged boaters to invest in ‘overengineered’ appliances.

He told PBO: “If I was lucky enough to have a yacht worth thousands of pounds, I wouldn’t risk its keeping in the winter to something I’d bought on Amazon or eBay for £50. I would want to buy something over-engineered with fireproof casings for any component with a slight chance of igniting.”

Dehumidifier

Even dehumidifiers set up to drain continuously should not be left unattended for extended periods

Meaco founder Chris Michael explained that compressor dehumidifiers “don’t freeze as standard in lower temperatures, they all have a form of defrost cycle to prevent this. The freezing water issue on the coils happens when they lose refrigerant due to an internal error, usually this means less water collected, it does not automatically mean you have a serious fault.”

Maintenance to avoid a dehumidifier fire

He advised against blindly trusting in CE-certified desiccant dehumidifiers that promised to run unattended 24/7 and at low temperatures, adding: “Everything requires maintenance, you can’t leave even the best dehumidifier on a boat for the winter and come back at Easter. For any dehumidifier to work, it needs to pull air in with a fan running continuously. When are you going to clean or replace the filter? If you don’t, you’re creating a problem because the airflow is not getting in and lint and dirt build-up will fall off.”

And this could, should a series of unfortunate events occur, form the fuel part of the ‘fire triangle’ that also includes the ingredients of oxygen and heat.

Matt Elliott, who has been called upon by local authorities in the past to report on domestic appliance fires all over Europe, added that it was not unheard of for mice to curl up inside warm dehumidifiers, the subsequent nibbling of wires and insulation internally can cause the source of ignition that manufacturers look to avoid by design, only to then become a source of fuel themselves. He warned of the false economy of buying cheap units from unknown brands:

“A CE sticker doesn’t mean it’s safe, it means it’s been created to a minimum standard.”

The need for users to secure dehumidifiers in case winds cause boats to heel and units to fall over, creating a fire risk, can be negated by a model with a ‘tilt switch’, that automatically switches off if the unit topples.

Desiccant dehumidifiers, which work using the absorption material like silica called zeolite, combined with a heater to remove moisture from the air, are recommended for boats in settings where temperatures regularly drop below 10°C, rather than compressor dehumidifiers, which perform best in warmer climates or within sheltered storage.

Compressor technology creates water and can freeze in low temperatures, as it works by creating a cold surface and when the warm, damp air from within the room comes into contact with this, condensation forms, and the water is removed from the air.

Asked to comment on dehumidifier fire risk, an underwriter at Haven Knox-Johnston told PBO: “While we do not stipulate what type of dehumidifier should be used within our policy, our stance is that the owner should follow professional advice; that it should be designed for the intended use on board the vessel and used/maintained in accordance with manufacturers guidelines.”

Safety tips for avoiding a dehumidifier fire

  • Follow the manufacturer’s instructions.
  • Keep on a level, flat surface in a well-ventilated space.
  • Before connecting to a pontoon electricity supply, check that the unit is upright.
  • Clean any filters regularly.
  • Don’t leave unattended for long periods
  • Choose a tilt switch model

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