Are these little gas heaters any good?

No good in your boat fella. They will burn up all the oxygen, you need some of it, create carbon monoxide, not a good replacement for oxygen, and what is worst, they will create condensation. Mind you if you have been breathing carbon monoxide instead of oxygen for a while, condensation wont matter too much.
 
The catalytic ones are great, so much so that I use one to heat my house over the Highland winter when the Storage heaters can't keep up.

No naked flame makes them safer than a standard calor heater. Give a very good heat output and can be economical.

They do create a lot of condensation, i've noticed. And, as Galadriel just mentioned while I was typing, like all bottle gas heaters, you will need decent ventilation for the Co they produce.

Main downside is good luck in getting hold of one, it seems that manufacture of them has been scaled back to a massive degree and they're becoming very rare in the UK. Expect to wait at least a few months from ordering to delivery, unless you're lucky enough to find a retailer who has existing stock.
 
I've just re-visited my physics brain and wondered why my carbon monoxide detector in the house hasn't gone off when I have this heater on, sometimes 5 hours a day.

The term Catalytic heater, means it is a catalytic process that generates the heat, therefore these SHOULD be clean burn heaters not generating CO. There's a wealth of discussion on the web available about this though if you want to research.

They do sap oxygen, however....
 
The catalytic heaters don't produce CO (presuming it to be working correctly) but do produce condensation. I have one on board my boat in addition to the blown air heater (1.6kW Propex) so it will warm up the cabin quite quickly (28ft boat) which is good for me as I use my boat year-round.

I then turn it off before retiring/when warm enough and leave the propex to run on the thermostat overnight.

The older ones can be found for sale on eBay and are stainless, which look better and should last a bit longer than the newer ones.
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I had one of those little ones on a motorboat back in the 70s. Yes, it needs ventillation and needs to burn blue NOT yellow, not ANY yellow. On that 18ft boat it sat on the back of a louvred cabin door opposite two mushroom vents and it kept us as warm as toast. The windows soon got wet through the condensation but as they got warmed it cleared.

Use with care.

Chas
 
I have had catalytic heaters on three boats and when I took one out of my current boat I installed it in a camper van. They are very safe, as anything that might fall on them will not ignite. Yes, they produce some condensation but barely more than your breathing does. The heat output is a little directional so they need to be installed with this in mind. Despite these minor disadvantages they offer just about the best and certainly the cheapest heating method without going down the warm air route. Except maybe a Tilley lamp, but that has a whole range of other disadvantages on a boat. I wouldn't sleep with one alight but for evening comfort they are excellent.
 
I had one, no real problem from condensation once I had changed to (red) Propane gas?

If a belief that propane combustion doesn't produce water makes you feel happy then good for you. The chemistry of the reaction indicates otherwise, however.

The reality is that to a first approximation each litre of fuel burnt (methane, propane, butane, paraffin, whatever) produces a litre of water. If you've no flue then that litre of water is released into the heated space. This is likely to result in condensation, most noticeably after turning the heater off as surfaces cool. This effect can be reduced by increasing ventilation, but this increases the heat loss since air you've paid to heat is replaced by cold incoming air.

Properly flued fuel fired heaters, or electric heaters, add no water to the heated space.
 
The heaters don't produce condensation, it comes from the now warmer inside of the boat which compared to the colder outside of the boat, condenses the moisture already in the air. Like a gin & tonic glass on a hot summer day. It's very much like the difference between warm air heating systems and using hot water into radiators: only warm air heating systems will wring the moisture out of the air. It's a simple trade off: catalytic heaters or radiators and ventilation which just brings in more cold air (!), or a hot air system. And if it's really cold outside, you'll need to insulate your hull and deck.

We have one, it works great, but mostly because of ur two dorade vents, cracking the forward hatch and leaving the hatchboards either out or the main hatch cracked open. Not very good for really cold weather, then you need much more heat output than these things can give you, but with a big trawler lamps and the C heater, they take the edge off, even down to about 35 degrees F.
 
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The humidity inside a boat is often approaching 100% anyway, so the extra moisture given off by a these heaters doesnt make a lot of difference. On a cold night, you will get condensation, period, unless you have a blown air system which dries the air.

Because the catalytic process is different to conventional combustion, these heaters do not give off CO, but they do consume oxygen, so as has been pointed out good ventilation is necessary although rather counterproductive on a cold night.

I have used a Catalytic type heater for many years both afloat and ashore, and reckon they are the safest source of portable heating. Bear in mind though that 1kw output will not do much to heat a cold cabin, giving little more than enough heat to warm your hands or feet!

And like others, I never sleep with them running. The risk of never waking up again due to oxygen depletion just is not worth it.
 
The heaters don't produce condensation, it comes from the now warmer inside of the boat which compared to the colder outside of the boat, condenses the moisture already in the air. Like a gin & tonic glass on a hot summer day. It's very much like the difference between warm air heating systems and using hot water into radiators: only warm air heating systems will wring the moisture out of the air. It's a simple trade off: catalytic heaters or radiators and ventilation which just brings in more cold air (!), or a hot air system. And if it's really cold outside, you'll need to insulate your hull and deck.

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its a bit of luck this isnt an exam, you get 0 out of 10 for that
 
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