Leaching of smoke as the fire burns down at night

Hi,

We are writing from NZ, where it is mid winter. We have the older model of this in our house http://www.wagenerstoves.co.nz/butler-multi-hot-water-heater (it doesn't have the round vent at the bottom of the door, but has the same door and window. We use it for warmth and for heating the hot water. We also throw a mattress on the floor and sleep in the lounge room. (The fire has fire bricks inside and throw out heat for much of the night).

No matter what time we light the fire, I fine that it is fine when burning hot, but when it dies down to the last coals, I have a tight chest, and a strong burning feeling in my lungs. (I usually wake to find this around 2am, but it can be during the day if we light a morning fire). We have a portable air filter, but it still takes a while to take effect and clear the air.

Last year we changed the rope round the door with some good effect. This year I have checked it and turned it, and it still seems fine. We have not changed the narrow one around the window, but I am hesitant to touch that. The bolt on the door handle will also easily loosen, which loosens the door seal. The "when we can afford it" plan is to have radiators running from the fireplace into the bedrooms. We will keep trying to fix the seal, but I am wondering about the whole air-flow thing. Is there something we can do to stop the back-draft later at night? Is this pretty usual for fires to have smoke come backwards as the fire cools? Is it a problem in the fire place air-flow, or the draft of the room itself?

Annie Hope : I can make some informed guesses as to what some of your problems are, and attempt to give you some simple thinks to try to help with your
smoke-back problems !
Stoves of this type try to achieve a clean burn of all the volatile wood gases 600dF / 350dC prior to heating the Wet Back area of your hot water heater, as the
fuel wood burns down to charcoal and embers the fire boxes temperature drops, the remaining exhaust gases are rapidly cooled down below 100dC the boiling
point for water in your wet back system, and the exhaust is no longer adequate to produce the vigorous Draft that you need to prevent smoke-back !

Step on is to carefully check and evaluate to condition of your Smoke pipe / chimney ! What is its condition ? ( an evaluation by a professional chimney sweep
is in order here ) are All fitting tightly sealed ?

Hopefully you have a stable climate during your winter season with little or no change of wind direction so that you can be confident that your smoke pipe /
chimney is located on the Lee Side of the house Structure through out your entire heating season !

The entire Smoke pipe / Chimney should terminate 4 - 5 feet above the peak of your homes roof or any other nearby object !

To reduce the amount of smoke-back you can attempt to plan on ending your evening fire slightly earlier, and ether remove the last of the coals embers into
a fire proof metal bucket and remove them to a safe out door location, or add more small kindling to help burn up the last of the charcoal / embers !

I hope this helps a little, and is timely ! For the good of The crafts ! Big AL !