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Thermx Caravan heaters?


Mel Good

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Just bought a boat today - I am totally new to the boating world! It's a Broom Commander 35 apparently - my question is around the gas heaters onboard - are they safe? What could I replace them with? They look pretty old and dangerous but I am worried about removing them as they are hooked up to gas. Any support is much appreciated 

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It doesn't appear to have a flue to the outside, so even if it works correctly and produces no harmful combustion products like carbon monoxide, it will produce much water which may give you a problem with condensation.

 

The Boat Safety Scheme inspector may also have a thing or two to say about it!

 

There are lots of alternatives from cheap Chinese ducted hot air diesel heaters for less than £100 to Eberspachers and others for more than £1000.

 

I have used one of the Chinese ones bought through eBay and it's been great for 4 years now with zero maintenance. I also use a Taylor's drip feed heater which uses no 12 volt at all which can be useful.

 

It all depends on what you want to spend and what space and layout you have for installation.

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Those things are called catalytic heaters and were popular in the 70s. I never quite understood how they worked, other than by taking gas and converting it into CO2, water vapour and heat by a means other than combustion. Being flueless the CO2 and and water vapour all ends up inside the boat so by today's standards, they are considered unsafe. I dunno if they would be a BSS fail. I've an idea the only flueless appliances BSS allows are cooking appliances.

 

 

 

 

 

 

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I'd be happy to have gas on board for cooking, but nothing else.

 

You've probably got gas pipes snaking throughout your new boat servicing different heaters, so you might be best to have just a single correctly sized  pipe to your cooker from your gas locker. You'll need a shut off valve, a pressure testing point and for safety's sake a bubble leak detector. If you're not confident with gas plumbing, best get a certified marine gas plumber to do it to make sure it conforms to the boat safety scheme requirements.

 

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Thanks so much - I was told that they were deemed safe in the 70's when the boat was made, were then unsafe due to open flame but were ok again. They do not look safe to me at all so thanks for confirming. @Bargebuilder what Chinese alternatives have you used? Would be good to have an idea of what's out there. 

 

My plan was to have them taken out safely and use the space well. 

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FWIW. They have a fibre blanket thing with metal threads in it (the catalyst). Gas passes through the fibre and is ignited on the surface. The blanket heats up and from what I can see, combustion then takes place inside the blanket, which just glows with no visible flame. There is a pilot flame right at the bottom centre of the blanket with a  small open flame that plays against a flame failure probe. In theory, when the oxygen in the boat starts to deplete, the pilot flame rises off its burner causing the flame failure get cold and shuts the heater down. I saw a manufacturer's demo on a short course, and it seemed to work in the early 70s. It should not produce much CO, spiders and dust in the jets willing, because it should have shut itself down.

 

It will fill the boat with water vapour and thus condensation. Personally, I would not use such things today, but I doubt the BSS etc. has any opinion on their use save for signs of charring around it.

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7 hours ago, Mel Good said:

Thanks so much - I was told that they were deemed safe in the 70's when the boat was made, were then unsafe due to open flame but were ok again. They do not look safe to me at all so thanks for confirming. @Bargebuilder what Chinese alternatives have you used? Would be good to have an idea of what's out there. 

 

My plan was to have them taken out safely and use the space well. 

The Chinese heater I installed was one of these: 

https://ebay.us/JLgutv

Not from that supplier and with a rotary output controller, off/on switch, but they've obviously gone digital in the last few years. In all other respects the heater and package look identical.

 

Everything you need is included, but depending on where your outlet is going to be relative to the heater, you might need to pick up a bit more ducting.

 

They are an easy enough DIY installation if you're handy.

 

Mine has worked brilliantly and reliably. I don't even visit my boat for the six winter months and it always starts first time in the spring.

 

They run on diesel, but even better domestic heating oil as it burns much more cleanly meaning it should go for many years without the need for any servicing at all: that's what I have done. Plus, it's cheaper to buy if you can get it.

 

The unit (yes I dismantled it) is pretty much identical to an Eberspacher in its mode of operation and indeed appearance. They are much less fussy about the fuel one uses and far less prone to failure, if you believe all the internet complaints about Eberspachers. 

 

The Chinese heater is cheaper to buy than the service kit for an Eberspacher of which it is a copy. 

 

I have a live-aboard friend who uses one and keeps a spare in his locker just in case it breaks down, because they are so cheap to buy!

 

 

 

 

 

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26 minutes ago, Bargebuilder said:

The Chinese heater I installed was one of these: 

https://ebay.us/JLgutv

Not from that supplier and with a rotary output controller, off/on switch, but they've obviously gone digital in the last few years. In all other respects the heater and package look identical.

 

Everything you need is included, but depending on where your outlet is going to be relative to the heater, you might need to pick up a bit more ducting.

 

They are an easy enough DIY installation if you're handy.

 

Mine has worked brilliantly and reliably. I don't even visit my boat for the six winter months and it always starts first time in the spring.

 

They run on diesel, but even better domestic heating oil as it burns much more cleanly meaning it should go for many years without the need for any servicing at all: that's what I have done. Plus, it's cheaper to buy if you can get it.

 

The unit (yes I dismantled it) is pretty much identical to an Eberspacher in its mode of operation and indeed appearance. They are much less fussy about the fuel one uses and far less prone to failure, if you believe all the internet complaints about Eberspachers. 

 

The Chinese heater is cheaper to buy than the service kit for an Eberspacher of which it is a copy. 

 

I have a live-aboard friend who uses one and keeps a spare in his locker just in case it breaks down, because they are so cheap to buy!

 

 

 

 

 

Thanks - I am pretty handy and do all the DIY around the house however I have no experience with a boat and am somewhat intimidated. YouTube will be my friend aided by this forum I hope. 

53 minutes ago, Tony Brooks said:

FWIW. They have a fibre blanket thing with metal threads in it (the catalyst). Gas passes through the fibre and is ignited on the surface. The blanket heats up and from what I can see, combustion then takes place inside the blanket, which just glows with no visible flame. There is a pilot flame right at the bottom centre of the blanket with a  small open flame that plays against a flame failure probe. In theory, when the oxygen in the boat starts to deplete, the pilot flame rises off its burner causing the flame failure get cold and shuts the heater down. I saw a manufacturer's demo on a short course, and it seemed to work in the early 70s. It should not produce much CO, spiders and dust in the jets willing, because it should have shut itself down.

 

It will fill the boat with water vapour and thus condensation. Personally, I would not use such things today, but I doubt the BSS etc. has any opinion on their use save for signs of charring around it.

Thanks - I think that backs up what I was thinking. I do love reusing things and upcycling if possible however this seems like a red flag in terms of safety. As you can see from the picture they are not in great condition and I would guess have not been serviced in a very long time. 

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When I was a student a group of us hired a 12 berth 70 footer. It was the last week in March, before the start of the school holidays, and so just about the cheapest week of the year. The boat's only heating was one of those catalytic gas heaters. It snowed on the first day. We all got wet through. The heater was absolutely useless! We had to resort to a pub to dry off!

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1 hour ago, Tony Brooks said:

FWIW. They have a fibre blanket thing with metal threads in it (the catalyst). Gas passes through the fibre and is ignited on the surface. The blanket heats up and from what I can see, combustion then takes place inside the blanket, which just glows with no visible flame. There is a pilot flame right at the bottom centre of the blanket with a  small open flame that plays against a flame failure probe. In theory, when the oxygen in the boat starts to deplete, the pilot flame rises off its burner causing the flame failure get cold and shuts the heater down. I saw a manufacturer's demo on a short course, and it seemed to work in the early 70s. It should not produce much CO, spiders and dust in the jets willing, because it should have shut itself down.

 

It will fill the boat with water vapour and thus condensation. Personally, I would not use such things today, but I doubt the BSS etc. has any opinion on their use save for signs of charring around it.

 

Tony

 

Presumably then it works in a similar way to portable gas lamps that use a cloth mantle?

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1 minute ago, buccaneer66 said:

 

Tony

 

Presumably then it works in a similar way to portable gas lamps that use a cloth mantle?

 

I don't think so because they seem to operate at a lower temperature and the mantle has a void in the middle while the "blanket" has not. I agree, the gas/air mixture must percolate through the blanket. I think it is some kind of chemical reaction using a catalyst (apart from the pilot flame) but we need  a chemist to explain the ins and outs.

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1 hour ago, Tony Brooks said:

FWIW. They have a fibre blanket thing with metal threads in it (the catalyst). Gas passes through the fibre and is ignited on the surface. The blanket heats up and from what I can see, combustion then takes place inside the blanket, which just glows with no visible flame. There is a pilot flame right at the bottom centre of the blanket with a  small open flame that plays against a flame failure probe. In theory, when the oxygen in the boat starts to deplete, the pilot flame rises off its burner causing the flame failure get cold and shuts the heater down. I saw a manufacturer's demo on a short course, and it seemed to work in the early 70s. It should not produce much CO, spiders and dust in the jets willing, because it should have shut itself down.

 

It will fill the boat with water vapour and thus condensation. Personally, I would not use such things today, but I doubt the BSS etc. has any opinion on their use save for signs of charring around it.

We had one on the first hire boat we had a long time ago. I understand that are one of the things that if its always been on the boat from pre BSS days then you can keep it. There was a chap on our moorings with one and thats what he told me.

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20 minutes ago, ditchcrawler said:

We had one on the first hire boat we had a long time ago. I understand that are one of the things that if its always been on the boat from pre BSS days then you can keep it. There was a chap on our moorings with one and thats what he told me.

 

We had one on an '80s NB and the BSS gives 'grand father' rights - apparently laws and rules cannot be backdated.

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I suppose safe is relative, as they were thought to be safe in the 70s. They were actually extremely common and so long as they are operating correctly may well be okay. Having said that, they give out a pathetic amount of heat and use gas to do so which is a very expensive heating fuel. 

 

You will be much better off and warmer if you switch to a diesel/heating oil heater.

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My boat had one when I bought it, only heating on it. Worked well for a while, but condensation was huge. Then it kept going out but still leaked gas and I decided it was a death trap and got rid. I think any still in place are going to be pretty ancient and unsafe.

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I used to use quite a few of these in various buildings but they had balanced flues. I think the make was drughazer. The smaller units seemed to be a sod to light and the flame failure thermocouples were a regular maintenance item...

 

we had some bigger units which were linked to a time clock to heat a large room and they seemed quite good but we scrapped them in the early 2000s. 

 

Wouldn't want one in a boat though.

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