Chimney - How Hot?

[Mac of Cygnet]

I have fabricated my own chimney, (which probably won't work), and I was considering using a Dektite thingy to seal it which has a maximum temp of 200 - 250 deg C.

 

Don't quite see what you mean by 'sealing' it. Don't you have a conventional collar over which the chimney is a push fit? I looked at 'Dektite', but couldn't see anything which would be compatible with a normal collar/chimney arrangement. Or perhaps we're not talking about a metal boat? A photo, perhaps?

[Higgs]

I have fabricated my own chimney, (which probably won't work), and I was considering using a Dektite thingy to seal it which has a maximum temp of 200 - 250 deg C.

 

There's only one thing I worry about with the stove, and heat; that's - going to bed and forgetting to shut the draft door. It's happened twice.

 

I also use the black heat resistant silicone. It stays flexible and stands the heat at the base, where the flue fits the top of the stove. My old flue also use to leave at an angle through the collar. The new flue, made to go straight through and leaves equal space between it and the collar, for packing.

 

The heat in the saloon is usually around 23c +/-, and I've never really noticed the flue getting excessively hot. May be because I've a backboiler and two rads and it's a narrow boat.

 

Good luck with your set up.

[system 4-50]

Don't quite see what you mean by 'sealing' it. Don't you have a conventional collar over which the chimney is a push fit? I looked at 'Dektite', but couldn't see anything which would be compatible with a normal collar/chimney arrangement. Or perhaps we're not talking about a metal boat? A photo, perhaps?

I am too embarrassed to admit to what this folly looks like until I've given it a serious field trial. If that works I'll come back with a pic, otherwise I'll quietly forget about it....

[Mac of Cygnet]

I am too embarrassed to admit to what this folly looks like until I've given it a serious field trial. If that works I'll come back with a pic, otherwise I'll quietly forget about it....

 

C'mon, give us all a laugh! Seriously, though, you could save yoourself a lot of hassle if you told us what you propose (and then go ahead and do it anyway... ......

[blackrose]

I note that everyone is talking about flues, while the OP asked about a chimney - not the same thing!

 

I think the measured temperature at the top of the flue that I posted will probably be a reasonable guide to the temperature at the bottom of the chimney a few inches away on the other side of the roof.

Edited September 23, 2012 by blackrose

[ditchcrawler]

I think the measured temperature at the top of the flue that I posted will probably be a reasonable guide to the temperature at the bottom of the chimney a few inches away on the other side of the roof.

I was on a friends boat last week and their stove has an insulated flue to the new RCD requirements and he said you could just hold your hand on it. So if its a new installation surly this is what the OP should be using, O I think he said the flue was £600 insulated stainless steel

[steven wilkinson]

no idea - but my son has a thermometer on the outside of his house stove flue, and that goes up to 350C - and it has done a couple of times!

[blackrose]

I was on a friends boat last week and their stove has an insulated flue to the new RCD requirements and he said you could just hold your hand on it. So if its a new installation surly this is what the OP should be using, O I think he said the flue was £600 insulated stainless steel

 

If the OP has an insulated flue then he should have an insulated chimney too. There's not much point using one without the other.

[ditchcrawler]

If the OP has an insulated flue then he should have an insulated chimney too. There's not much point using one without the other.

I thought the flue was to reduce the fire risk inside the boat against the internal cabin lining, the Chimney is outside and not exposed to the cabin lining

[Keeping Up]

Again, on a boat much of the heat radiation comes from the flue. I believe the recommendation (rather than requirement) of the BSS is now only that it be insulated near the collar. I can see the logic in ensuring that it is cool where it passes through the roof, but the next logical stage after all-insulated flues is to insist that entire body of the stove itself must also be double-insulated to ensure that it doesn't get hot.

 

Thankfully over the years they have retreated from the requirement for a foot-square hole in each of the front doors (as the first draft of the ventilation requirements called for) and the recommendations that all parts of the stove must be further than one metre from the sides of the boat (as was mooted at one point!). We shouldn't lose sight of the fact that stoves are there to heat the boat and that if the regulations are not sensible, they will be by-passed, as for example by those idiots who block up their door vents in the winter because it gets cold.

[John V]

I use enam. single wall 5" below deck, above deck it continues inside a 7" dia. 3/8" walled steel pipe welded to the deck (no collar needed as deck is 8mm) the top of the inner is level with the outer and the gap is packed with glass rope topped with a sealing layer of high temp. silicon sealant. The deckhead in the cabin is made of "Hardibacker" cement based board (sold in tiling shops) for an area around the flue, incidentally this takes paint readily.

The single wall section can get very close to glowing when the stove is blazing but as the bulkhead behind it is tile/hardibacker/steel its not a prob.

Edited September 24, 2012 by John V

[rjasmith]

I was on a friends boat last week and their stove has an insulated flue to the new RCD requirements and he said you could just hold your hand on it. So if its a new installation surly this is what the OP should be using, O I think he said the flue was £600 insulated stainless steel

 

As a very small point of information (I love being pedantic!!) - the new "requirements" are nothing to do with the RCD (nor really to do with the BSS either, although BSS do recommend them on their website rather than in the BSS Guide).

 

Interestingly the RCD standards do not specifically mention solid fuel stoves anywhere!

 

The new requirements are a British Standard Code of Practice written at the behest of MAIB following the Lindy Lou incident.

 

Richard

[blackrose]

I thought the flue was to reduce the fire risk inside the boat against the internal cabin lining, the Chimney is outside and not exposed to the cabin lining

 

The other function of an insulated flue and chimney is to ensure flue gasses do not cool and maintain draw from the stove. However, this is only really an issue on much longer flue & chimney arrangements than we have on our boats.

 

If flammable foam and cabin linings are properly cut back or covered with fire-retardant board prior to flue installation there should be no fire risk with a single-wall flue. Unfortunately the obvious charring of linings that you see when you walk onto some people's boats shows that this isn't always done.

Edited September 24, 2012 by blackrose

[snigsnig]

Recommendations for stove and flue installations are there for a reason - safety. I really don't get some of the reactionary whining from certain members on this board, and consistently pointing out that the recommendations are ONLY recommendations and not a requirement, as though they are wrong to be published at all.

 

When installing my stove I started from what I considered to be the most important factor - that my boat could potentially catch fire and I could die a very horrible death. Hence I followed recommendations as best I could, did a little research, used a little of my own judgement according to the exact specs and fitout of my boat, and am left with an installation that I consider safe.

 

God help anyone who buys into the dismissive and irresponsible attitude of some members here, slaps in a new stove to any old spec, and ends up toast.

[luctor et emergo]

There seem to be more boats sunk, than set on fire.

The biggest cause of boat fires, appears to be operator error, often after consuming alcohol.

 

Be careful outthere

[Mike Tee]

I've got a 'Stovax' thermometer (magnetic) about 10 inches above the fire on the flue. This shows recommended working temp between 125c to 250c, I assume that is for single skin, as that is what I have. I keep an eye on it after lighting, and close down the air intake when it gets to the operating temp. Don't know how accurate the thermometer is, but it all seems to work for us. At least it gives an indication that the flue is up to heat, and saves overdoing it.

 

I also posted about the Ecofan, and that definitely keeps the ceiling cooler than not having one.

[bowten]

Recommendations for stove and flue installations are there for a reason - safety. I really don't get some of the reactionary whining from certain members on this board, and consistently pointing out that the recommendations are ONLY recommendations and not a requirement, as though they are wrong to be published at all.

 

When installing my stove I started from what I considered to be the most important factor - that my boat could potentially catch fire and I could die a very horrible death. Hence I followed recommendations as best I could, did a little research, used a little of my own judgement according to the exact specs and fitout of my boat, and am left with an installation that I consider safe.

 

God help anyone who buys into the dismissive and irresponsible attitude of some members here, slaps in a new stove to any old spec, and ends up toast.

I totally agree.

[nb Innisfree]

Advantage of a steel flue is it's ability to withstand a good hammering to dislodge any build up of internal deposits. Best done just before first light up in the autumn when the deposlts have dried out and hardened and are rigid and easily broken up. Much more effective than using a brush.

[Tuscan]

Having had a new stove fitted recently I am amazed at the difference in protection installed compared with the stove on my last boat, on balance this is a good thing but I am reminded of the heap of kids that slept on the floor and settee next to the old fire year after year.