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How to use a water vapour fireplace

Updated: October 2026

The bottle is still empty and the first evening is the one that usually goes wrong. How to use a water vapour fireplace starts with which appliance you bought. A Dimplex Optimyst stove takes filtered water in a bottle and can run the mist with the heater off. A generic insert may claim a hose, a humidifier, or no heat at all. This page is the first fill and the first checks. Products Compared used Dimplex’s UK care sheet and amazon.co.uk review themes from 15 October 2026. A qualifying purchase can earn a commission at no extra cost to you. The rows are on the [water vapour fireplace comparison](/hub/fireplaces-and-stoves/water-vapour-fireplace).

The bottle is still empty and the first evening is the one that usually goes wrong. How to use a water vapour fireplace starts with which appliance you bought.

Our top picks

Generic 3D water-vapour insert 500 mm

Best overall

Generic 3D water-vapour insert 500 mm
3.2/10about £266.80
View offer
Dimplex Dimplex Gosford Optimyst

Rank 2

Dimplex Dimplex Gosford Optimyst
8.1/10about £639
View offer
Dimplex Dimplex Bayport Optimyst

Best value

Dimplex Dimplex Bayport Optimyst
7.9/10about £419
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On this page
  1. 1.Fill the right product
  2. 2.Water and how long it lasts
  3. 3.Flame without heat, and the door
  4. 4.Light on, no mist

Fill the right product

On an Optimyst stove the water sits in a bottle that feeds a sump under the fuel bed. The Gosford, Fortrose, Willowbrook, Evandale, and Bayport listings name that bottle, and the bullets say a fill lasts up to 8 hours. Seat the bottle so it seals, and seat the transducer so it sits flat with its lead connected. If the transducer is proud of the socket, you get light and no mist. An insert is a different fill. Several bullets claim an automatic inlet and filtered water. B0FYFSJ9MT mentions a hose. B0GH7BK73V says the unit must be wired. Do not paste the Optimyst bottle steps onto a hose. If the text says the insert must be wired, stop and use an electrician. A new circuit or any bathroom work is already that job under Approved Document P.

Water and how long it lasts

Use filtered water in an Optimyst stove. The UK care sheet says that, and it tells you not to use de-ionised water. The brand’s shop FAQ also mentions de-ionised water, so the two pages conflict. Prefer the care sheet, then the manual in the box. Hard tap water leaves scale on the transducer and the mist thins. Clean about every two weeks, and do not leave water standing for more than two weeks. Empty the sump if the stove will sit unused. The hour figure is a ceiling. The care sheet says about 8 to 10 hours a fill for Optimyst as a class. The bullets say up to 8 hours. Stored reviews are often shorter than that ceiling. Keep a jug of filtered water nearby so the transducer is not running dry.
Generic 3D water-vapour insert 500 mm

Testsieger

Generic 3D water-vapour insert 500 mm
3.2/10about £266.80
View offer

Flame without heat, and the door

The mist and the heater are two switches on the five Dimplex stoves. You can run the flame with the 1 kW and 2 kW fan off, which suits a room the radiators already warm. With the fan on, 2 kW for an hour is 2 kWh, times your unit rate. The care sheet’s figure of about 200 W for flame-only is a class note. It is not the Bayport’s 80 W field, the Evandale’s 90 W field, or the Fortrose’s 130 W field. Dimplex describes the flame as cool. The glass still wets on start-up, and owners report doors that stay wet. Wipe it once the stove has settled, and read the manual before you prop a door. Keep the heater clear of curtains. Electrical Safety First says a portable heater should have a UK 3-pin plug and is a poor overnight habit.

Light on, no mist

When the lamp is lit and the bed stays dry, unplug the stove before your hands go in the sump. Confirm the bottle is feeding the sump, seat the transducer flat with its lead connected, and clear scale if the stove has been run on hard water. If the sump is full and you still see an empty-tank error, reseat the nozzle. That fault is already in the Bayport reviews. A missing remote, on the Willowbrook and the Bayport, is a separate fault. Stop if the mains lead is damaged, if you smell burning, or if the breaker trips. Do not open the heater. For a wired insert, those bottle checks are the wrong next step.

Common questions

What water goes in the bottle?
Filtered water, for a Dimplex Optimyst stove. The UK care sheet says not to use de-ionised water, even though a shop FAQ mentions it. Follow the sheet and the manual in your box. Hard tap water is the usual reason the transducer scales and the mist fades.
How long should a fill last?
The listing ceiling is up to 8 hours, and the care sheet says about 8 to 10 hours for Optimyst as a class. Stored reviews are often shorter: every 3 to 4 hours on a Bayport in constant use, and about 3 hours in one Willowbrook report. Judge the first evenings in your own water, and top up before the sump runs dry.
Can the flame run with the heater off?
Yes on the five Dimplex stoves in this set. The listings state a flame-only mode as well as 1 kW and 2 kW. Two inserts state that they have no heat, so there is no heater switch to leave off. Where a listing never states a wattage, do not assume a hidden fan.
Does this humidify the room?
Dimplex says the humidity from an Optimyst effect is not significant. Treat these stoves as a flame effect plus an optional heater. Some insert bullets promise dry-air relief. No review stored for those listings measures the room.
What must I not do myself?
Do not open the heater, keep using a damaged plug, or ignore a burning smell or a tripping breaker. Do not wire an insert whose text says it must be wired, and do not add a new circuit or work in a bathroom yourself. A US note about adding salt appears in North American Dimplex material and is not the UK care sheet.

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Sources

Public UK sources and the Dimplex care sheet, read with the amazon.co.uk listings on 15 October 2026.

  1. Dimplex Optimyst collection (retrieved 15 October 2026)
  2. Dimplex Fortrose Optimyst electric stove (retrieved 15 October 2026)
  3. Dimplex Optimyst maintenance guide (retrieved 15 October 2026)
  4. Approved Document J: combustion appliances and fuel storage (retrieved 15 October 2026)
  5. Smoke control area rules (retrieved 15 October 2026)
  6. Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 15 October 2026)
  7. Approved Document P: electrical safety in dwellings (retrieved 15 October 2026)
  8. Electrical Safety First: portable heaters (retrieved 15 October 2026)