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14825 posts

Uber Geek
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  # 2057280 16-Jul-2018 18:45
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Guessing the old one under the casing sleeve is welded? How did the old flashing fail? This is how they are often done by plumbers https://steelandtube.co.nz/product/pur/publications/design/chimney-flashing-round-flue

 

 

 

Just looking at your photo, that doesn't look to be a masport flue. The cowl and angled part looks very different. Mine looks like the one in the main photo on this PDF https://www.masportheating.co.nz/LiteratureRetrieve.aspx?ID=139412  . Was there a reason why they did use the manufacturers one?


791 posts

Ultimate Geek
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  # 2057579 17-Jul-2018 09:21
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They said they didn't use the Masport flue I provided since they wanted to reuse the existing flashing, so sleeved their flue over the top of the old one.  I don't know how the old one was flashed to the roof since I hadn't been up there in decades.


 
 
 
 


236 posts

Master Geek
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  # 2057585 17-Jul-2018 09:33
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gchiu:

They said they didn't use the Masport flue I provided since they wanted to reuse the existing flashing, so sleeved their flue over the top of the old one.  I don't know how the old one was flashed to the roof since I hadn't been up there in decades.



So the flashing and the bottom of the outer casing is from the old flue. That should reassure you it’s weather-tight.

Normally, for a replacement woodburner, the whole flue is required to be renewed. It’s the inner flue that gets the wear though.

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Ultimate Geek
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  # 2057633 17-Jul-2018 11:04
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I think he is saying that the whole flue was replaced but he kept the existing flashings, and that part of the old flue external casing that was attached to the flashings.


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Master Geek
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  # 2057659 17-Jul-2018 11:55
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gchiu:

I think he is saying that the whole flue was replaced but he kept the existing flashings, and that part of the old flue external casing that was attached to the flashings.



That’s exactly what I said.

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Ultimate Geek
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  # 2058390 18-Jul-2018 16:12
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Well the installation of the Cromwell passed inspection except that I had to move my smoke detectors higher up so that they were within 500 mm of the apex of the roof ( in the hallway where the bedrooms are ).

 

I got some Tui wood to burn and some kindling but need an intermediate size where the kindling lights the intermediate size wood which then lights the larger pieces of wood.

 

I took this very brief video https://youtu.be/Ae4kTGHCT_k and I stated that I thought it wasn't working yet at 50 minutes, but perhaps it was.

 

Anyway, the lesson is to split some intermediate pieces of wood to help get the burn going.


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Ultimate Geek
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  # 2058424 18-Jul-2018 18:11
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Looking at that burn I definitely wouldn't have started the downdraft. I only initiate when it's blazing and from then it can stay down all night unless you let it get really low.

 

Green light doesn't always mean you should enable it. The temp sensor is behind the main chamber and isn't completely reliable.


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Ultimate Geek
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  # 2058426 18-Jul-2018 18:26
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Psilan:

 

Looking at that burn I definitely wouldn't have started the downdraft. I only initiate when it's blazing and from then it can stay down all night unless you let it get really low.

 

Green light doesn't always mean you should enable it. The temp sensor is behind the main chamber and isn't completely reliable.

 

 

The Cromwell doesn't have any green lights or temperature sensors.

 

I'm going to get a stove thermometer to see if it helps to determine when one needs to start the downdraft.

 

 


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Ultimate Geek
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  # 2058428 18-Jul-2018 18:28
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gchiu:

 

Psilan:

 

Looking at that burn I definitely wouldn't have started the downdraft. I only initiate when it's blazing and from then it can stay down all night unless you let it get really low.

 

Green light doesn't always mean you should enable it. The temp sensor is behind the main chamber and isn't completely reliable.

 

 

The Cromwell doesn't have any green lights or temperature sensors.

 

I'm going to get a stove thermometer to see if it helps to determine when one needs to start the downdraft.

 

 

 

 

 

 

Hah ah true. Well I would definitely leave it longer than that anyway. Get some coals forming.


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Ultimate Geek
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  # 2058592 19-Jul-2018 08:44
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Wheelbarrow01:

 

The fire had been lit for 10 minutes before I filmed it. I know the video is not great quality when zoomed in, but I couldn't see any smoke with my own eyes either. I am pretty impressed.

 

 

That's very impressive for a 10 minute burn, and I wonder if it's just all kindling burning.  The docs with the Cromwell say it takes 40 mins to get a good downdraft established.


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Ultimate Geek
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  # 2058594 19-Jul-2018 08:46
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pctek:

 

Chimneys emit smoke, they are supposed to.

 

 

Nope.  Smoke is unburnt fuel that is being lost to the environment.  Basically unburnt dollars.

 

Or, to put it in the amended old saying

 

"where there's smoke, there's an inefficient fire"


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Ultimate Geek
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  # 2058601 19-Jul-2018 09:03
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Does anyone have the theory as to how the ULEB burners work?  I'm wondering why it takes so long ( 40 mins ) to get the downdraft established.

 

My guesses are

 

     

  1. The top burn chamber has to burn hot enough to drag enough air into its chamber to create sufficient volume of air to create the escape velocity out of the flue so that when you switch the downdraft on, the flow is sufficient to force the fire into the secondary burn chamber and then out the flue
  2. The flue has to heat up sufficiently to accelerate the draft sufficiently to maintain the draft when switched into down draft mode

 

If the latter is the case, would preheating the flue with an electric element speed up the time to reach the downdraft?

 

I know that in the rocket fire stoves it takes very little wood to switch the fire from being vertical to along the horizontal burn chamber so that the secondary ignition takes place inside the secondary burn chamber.  So, I'm guessing the answer is mainly in number 1, getting sufficient air into the chamber to force it out the flue at the other end.


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Ultimate Geek
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Chorus

  # 2058617 19-Jul-2018 09:14
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gchiu:

 

Wheelbarrow01:

 

The fire had been lit for 10 minutes before I filmed it. I know the video is not great quality when zoomed in, but I couldn't see any smoke with my own eyes either. I am pretty impressed.

 

 

That's very impressive for a 10 minute burn, and I wonder if it's just all kindling burning.  The docs with the Cromwell say it takes 40 mins to get a good downdraft established.

 

 

I have developed a pretty good system for my Masport Mystique through trial and error which seems to work well for me. In terms of newspaper, I tear up the full reams at the 'binding' so that I have full (but single) sheets.

 

I then screw these up and place 8 loose paper balls around the central downdraft ring. I then place a further two flattened balls on top of the down draft ring.

 

I generally use split pine offcuts for kindling. I normally place a row of 5 pieces, with an additional layer of 5 more pieces at right angles.

 

On top of that I place two more pieces of bigger pine offcuts (standard 4x2 size).

 

I light the paper at the front, and immediately shut the door. Within 5-8 minutes, the fire will be roaring and I will then add 1 medium piece of pine and one medium piece of oregon. After another 2 or 3 minutes the LED indicator will change from red to green and I will then activate the downdraft. Sometimes I don't wait for the indicator to change - I can generally tell when the fire is roaring enough to engage the downdraft. After another 10 minutes or so, a bigger oregon log can be put on with the downdraft reactivated almost immediately afterwards.

 

From looking at the video that was posted above, it seems to me that there is a big stack of fuel above the downdraft ring, but no or very little fuel around the ring towards the edges of the burning area. You need to have fuel and some embers scattered around the downdraft ring to get a decent burn through the downdraft in my experience. I always tend to arrange my wood so that it forms a sort of square around the ring - I try to avoid placing logs etc directly in the centre of the ring itself as this will hold the log artificially in space if you get my meaning. This results in slow and incomplete burning.

 

I might try and video my routine tonight and throw it up on youtube. It could be interesting to see what people think.


791 posts

Ultimate Geek
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  # 2058619 19-Jul-2018 09:16
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Wheelbarrow01:

 

I might try and video my routine tonight and throw it up on youtube. It could be interesting to see what people think.

 

 

Yeah, please!

 

And any issues with placing spuds wrapped in tin foil to cook in the upper burn chamber once it's all going well?  Googling the melting point of tin foil it says 680 deg C.


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Ultimate Geek
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Chorus

  # 2058949 19-Jul-2018 18:27
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gchiu:

 

Wheelbarrow01:

 

I might try and video my routine tonight and throw it up on youtube. It could be interesting to see what people think.

 

 

Yeah, please!

 

And any issues with placing spuds wrapped in tin foil to cook in the upper burn chamber once it's all going well?  Googling the melting point of tin foil it says 680 deg C.

 

 

So I've made a trio of videos for your entertainment (or otherwise lol)

 

https://youtu.be/5oa7jOlYTnc

 

https://youtu.be/wiL1QcxPOis

 

https://youtu.be/hl7bnDx8dSg

 

Sorry, it's pretty clear I was not born to narrate gripping tv but you get the idea...


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