Updated 30th Sept 2018

~ 'Axeman' FireFlue ~
Quality stainless steel hot water maker & energy saver

Updated: 23 July 2013

Page 1 - Introduction
Page 2 - Pricing - ordering & conditions of sale
Page 3 - Water connection drawing
Page 4 - Installation Notes
Page 5 - Pressure test & Safety valve
Page 6 - Added notes ref fitting
NOTE Go here for added technical information

The Axeman 'Fire - Flue' is stainless steel hot water heater having a water jacket fitted to a heavy duty central tube that fits between the top of the firebox and the chimney flue for maximum heat absorption from the fire and energy saving.  This means that much of the heat exiting the fire box is in contact with the central tube, and the heat is transferred into the water contained within the water jacket. 

The flue comes in a variety of lengths and widths and can be made to order.

If the top of your hot water storage tank is mounted higher than the hot water exit of the Fire Flue the water will flow to it unaided by a pump due to convection causing hot water to rise, for as the water inside the jacket heats up the hot water rising upwards starts to flow and move towards the top of your existing hot water tank, and the colder water at the base of the main tank moves towards the lower intake of the water jacket.


The unit can simply be inserted directly into the outlet of the firebox by elevating the chimney flue upwards and then dropping the Fire Flue into the top of the stove outlet, the chimney flue drops into the top as in above image.  The Fire Flue has  standard 6" diameter flue.

Whether you have an inner coil heat transfer system or an high pressure electric one, if you fit a 'Fire - Flue' then you will be happily surprised to find that you will have a greater amount of 'free' hot water, in that the heat presently rising up into the sky from your fire will be used to heat your water rather than being wasted.  The product will help people to increase their hot water storage and lower their electricity bills.
If you are using electric heating you will be able to switch it OFF whenever the fire is being used, for the  'Fire - Flue' system will keep your water cylinder very hot.
The basic unit as in image 2 above is plain standard finish.  The image at top was a special order having a 'polish' finish, and if you wish to have such then it will cost a little more.
It is easy to install, simply insert the Axeman 'Fire - Flue' heater between the chimney flue and the fire stove by elevating the chimney upwards, and connect it into the existing cold & hot lines.  Due to the very large heat contact area the fire flue has a huge advantage over a conventional firebox heating coil and this leads to more hot water being produced in any given time frame.
This unit is a high pressure one 150 psi+ and can be used to fit to both low & high pressure systems. 

The inlet and outlet fittings are three-quarter inch suitable for copper tube connection directly into your existing water tank.

If you are using a low pressure tank system or a high pressure system the only requirement is that the hot water exit of your existing water tank is situated higher than the top exit of the 'Fire - Flue' heater, as this will enable a 'convection' flow of hot water to flow from the heater top 'exit' upwards to the top of the main house tank. 

As the hot water flows into the top of the tank, the cold water at the base of the tank flows out and into the lower end 'inlet' of the 'Fire - Flue' heater water jacket.  It just keeps circulating round and round getting hotter all the time without the need to pump it around.  The longer the 'Fire - Flue' heater the more heat generated. 

Page 2

~ Pricing - ordering & terms and conditions of sale ~

Please Note: The prices given below may not reflect the price of the day because this web content is not updated very often, so please request a price quote when you make an enquiry.

The standard unit is adequate for a small home, and the largest unit is needed when one has the need of added water heating to the home or a large family. The approximate flue lengths are:

Standard heat – 620 mm long (24") Fire Flue $ 640. (Australian currency)
Maxi heat -
780 mm long (31") Fire Flue $ 800.
Super heat -
1030 mm long (40") Fire Flue $ 990.

Above prices include delivery anywhere in Australia

Longer or wider flues are made to 'order & price quote.'

Note: All flues are 6" flue diameter unless ordered differently
Note: Larger or smaller units of any diameter or length available

The unit will require to be fitted by a plumber or 'handyman' and the copper pipe needed and the cost of fitting is not included in the sale price of the unit.

These heavy duty units are made to a very high standard of manufacture.
If your chimney flue is a different diameter e.g. 5" or a longer one needed then we can alter the design and quote you.

 'Axeman' - 'Fire - Flue' - water heaters heaters

Water connection view

There is already water connected in and out of a hot water reservoir.  It is simple to cut the copper pipe just below the cold water inlet at the lower end of the reservoir and place a 'T' piece in and connect it to the lower end of the fireflue. this enables cold water to flow into the fireflue

The same is done at the top of the reservoir, and a connection is made to the top of the fireflue. The arrows 'C' show the cold water moving to the fire and the arrow 'R' denotes water RISING as it is being heated, and arrows H show hot water moving to the top of the reservoir and then down into it.

When no hot water is being used there is no cold water entering the water tank reservoir from the mains supply, but due to the convection caused by the fire, there will be water flowing out of the water tank going into the fire section and returning to the top of the tank, and the water in it is getting heated up all the time the fire is operational.

If you are using a low pressure copper tank then it will already have two pipes coming out of its side that go to the heater coil and you simply 'plumb' your FireFlue into these fittings.  In the event that your water is 'corrosive' and your copper tank starts leaking then I can supply you with a  1.5mm heavy duty low pressure  stainless steel tank  that you can insert into the system using your old outer cover.   You would need firstly to specify  your home system pressure, be it stand alone gravity or pump assisted.

Installation Notes

From all of us at Axeman 'Fire Flue' Water Heaters, we hope this product serves you well for many years and you find it of sound quality and up to expectation. Herein are a few notes of advice for installation of the unit. These notes are for the installation of the Axeman flue water heater only, and not for the plumbing of and the necessary pipe work which needs to be done by a person of appropriate knowledge and skill to maintain a trouble free operating system.

  1. FIRST CHECK- Is your existing chimney flue 'wire stayed' on the roof for support? If so the guy wires will need to be released before installation and then readjusted for tension afterwards.
  2. To fit the heater. Generally it is easiest to have a helping hand, one to lift the existing flue and hold, while the other one cleans the seating area on the stove top if necessary with a screw driver or other scratching implement, after which lift the Axeman into place. A rubber hammer or such { steel hammer with a wood striker } may be needed to seat the Axeman all the way into the stovetop collar. The existing flue can then be dropped down into place on top of the Axeman. Sealing compound should not be needed unless for some reason it is a loose fit.
  3. When installed, the Axeman needs to be solidly in place and in a vertical or straight up position, not leaning in any way
  4. Now that the Axeman is in place, your existing flue has risen in height above the roof. Please make sure the exposed flue has adequate support. It may be necessary to add guy/ stay wires to the hat section to help support the flue in high winds. If you had stay wires, re-attach at new length, or if you wish to maintain the 'hat' height from the top of roof you can simply shorten the flue section that fits into the top of your Axeman FireFlue by cutting off the same length as the length of your FireFlue .
  5. Once the Axeman is installed. If you would like to keep the shiny stainless colouring, it is paramount that you do not light a fire until you have a water supply connected and the FireFlue is full of water, as this maintains a steady temperature at all times. If the fire is lit with no water supply to the jacket, the stainless steel will heat up to a very high temperature {as expected} and discolouration will happen. It will turn a shade of tan to light brown, getting darker with height of temp. If this happens and you wish the original colour, the unit will need to be removed and re polished. No integral damage will have been done.
  6. On start up, one may hear steam building in pressure or bubbling inside the jacket, this is no cause for concern as it may take 10 mins plus for the system to heat up enough to initially clear all air out of the pipe work and start the necessary and normal flow cycle of the hot water.
  7. Once up and running you should feel the cold or cooler water entering in the bottom inlet port and the hot or hotter water exiting the top fitting. If this is happening, your system is operating correctly.
  8. As a safety precaution for your system. All hot water tanks need and are supplied with a pressure release valve. They are fitted as a safety measure to regulate or maintain the system pressure at safe and appropriate levels. They are also set or mounted at the top of tanks to allow venting off of air. Generally these come factory fitted. Different water supply pressures will require the appropriate valve pressure release rating for the system to operate as required. If your water system uses a pressure pump or gravity feed, then get your plumber to check and ensure that the safety valve release pressure is set in accordance to the operating pressure of your water supply. It needs to be set at a pressure release that is within the pressure pumps or gravity feed limits of operation.
  9. Each unit is checked and cleared by applying a static pressure test of 150 psi or 10 bar. This is applied to test for any possible leaks and overall integrity. All precautions in manufacture have been taken to provide you with a quality hand made and Australian designed product. Thank you for your custom and happy heating.
  10. We appreciate any feed back that comes our way so please let us know how you feel about your installation or if you have any queries and concerns.
  11. If you have a plumber in your area that you would like to recommend to others who may want to install an Axeman Flue Heater, please with their consent , forward their contact and we can pass it on.

Pressure test & safety valve

Each and every standard  unit  is checked  and cleared by applying a static pressure test of 160 psi or 1100 Kpa .  One in every batch of low pressure units is checked at 200 psi or 1400 KPa.  My standard high pressure units will take much more pressure than this. This pressure test is applied to test for any possible leaks and overall integrity. All precautions in manufacture have been taken to provide you with a high quality product that is hand made in Australia. Thank you for your custom and happy heating. 

All commercially available hot water tanks are supplied with a pressure release valve or a fitting to accept one.  This is to save the storage tank from possible damage as it is the weakest system component. They are fitted as a safety measure to regulate or maintain the system pressure at safe and appropriate levels.  In a mains or council supply this can happen from local demand or council works.

As a safety precaution for your system if it is 'home made'.  Most hot water tanks are supplied with and need a pressure release valve.  This is to save the storage tank from damage. They are fitted as a safety measure to regulate or maintain the system pressure at safe and appropriate levels in case of hydraulic lock. Pressure surges from a mains supply or normal everyday expansion as we heat up the cold water that we consume as hot. 
If your system is home made and does not have a safety pressure relief valve then when fitting a FireFlue it is imperative that you also have a pressure relief valve fitted to the top of your hot water tank. This is because when lighting the fire at any time from cold, (gone out) the Fireflue is so efficient that it can generate steam as it initially heats up. This is because the water being heated within it is initially stationary and has not begun to circulate around the system. This steam can increase the pressure in your system and must have the means to vent off safely. Naturally each time you open the hot water tap any trapped air will be released and 'spit' out of the tap. This is normal.
The pressure release valves are also set or mounted at the top of tanks to allow venting off of air when they need to self operate or, if they need to be manually operated to release trapped air. Generally these come factory fitted at a safe working pressure for the tank in question.

Gravity  water supplies need not be a concern as they are generally of very low pressure and  the water is moved back and forth in the pipe work with little effort or pressure change.  Any air build up is ejected at the hot tap.  This also applies for mains or council provided water, though pressure changes do occur from demand changes through the day or works that takes place for repairs.

As a safety precaution . If your water system uses a pressure pump without an air tank i.e.  Grundfoss automatic pressure system.  Hydraulic lock or pressure build up will occur quickly in a closed loop/system..  If you are fitting a new release valve for any reason, check and ensure that the safety valve release pressure is set in accordance to the operating pressure of your hot water tank.

In a closed system  { home pressure pump }, the pump has its own non-return valve. This acts as a one way valve one end and your tap is the valve the other end.  As we heat up the water in the tank, it expands, cannot escape and the system pressure rises very quickly.  Any small expansion  can easily add many hundreds of psi (lbs pressure) to a 'locked system' if no pressure relief valve or  expansion control valve,  is fitted.  This can 'pop' ones tank, thus the need for pressure release valves.  Pressure pumps with air tanks will absorb this though the new age brings tankless pumps which are in themself a none return valve or ON/OFF valve.

In a closed system, if no water is consumed whilst the storage tank is being heated through its cycle, pressures will rise, and a small water loss will or may occur out of the release valve as water  heats up .i.e. you may lose 1 to 2 litres from a standard tank every day. { totally dependant on home use at the tap at this time } I would expect one to estimate or allow 1% loss of water in our tanks as an average with the normal temperature differences we would expect in a home situation.

All the 'above' is saying is that you must have a pressure relief valve fitted and that its pressure is set according to the system requirements. I recommend that a 70 psi safety relief valve be fitted to the fireflue system if you are not on a town water supply with a system already installed having its own pressure relief valve already in place.

Added notes ref fitting:

Make sure that the hot water entry point at the top of the house hot water cylinder is higher than the exit point of the Fireflue, and has NO downwards loops that will create air locks. It needs be so in order for the 'convection' process to operate.  It is also necessary so that any 'air' in the fireflue heater system can 'exit' and flow upwards into the hot water reservoir cylinder and be released through a hot tap when opened.
You cannot use a fireflue if your water tank is situated in a basement and thus below the fireflue exit pipe, for hot water cannot flow downwards.
The hot water copper pipe exiting the top of the fireflue needs to be 'lagged' so as to prevent heat loss between the fireflue and the hot water tank reservoir, for copper pipe that is uncovered loses heat to the surrounding air. You can either purchase lagging material or simply cut 2" wide strips of carpet material or underlay and wind it around the length of the copper pipe. 
The cold water copper pipe at the bottom of the home hot water cylinder that connects to the lower end of the fireflue also needs to be 'lagged.'  This is due to the fact that once the water cylinder contents become 'warmer,' then warm water exits the lower end, and if this pipe is also lagged then the water entering the fireflue will be warmer and the water exiting it will be even hotter.  This will ensure that your water reservoir gets hotter quicker.

Note: This site is still under construction and a sketch detailing positioning of hot water tank in relation to the  'Axeman'  'Fire - Flue' heaters will be added.

Answers to questions asked are here;

What size would I need -- roughly 'per person'? - smallest will do for 4 people

Can I use it for floor heating? Yes but it would need a separate holding tank and a pump to pump the water DOWN and around under floor

What type of 'rise' do I need? any amount is enough, the more rise the faster the flow to the top of the water reservoir.

Will there be any problems with pressure build-up -- are pressure / heat-relief devices needed -- how is overheating reduced? No problems, all water tanks have a pressure release system fitted by the plumber on original installation

How can / do I switch on / off from electric heating?  On power board

Do you have a picture of a simple 'house' design? No

What if my pipes aren't near the heat source?  Water tank can be anywhere as long as it is higher than fireflue, but the nearer it is the better it is for heat transfer

What are 'EPA' emissions and how do they affect the 'Axeman'? NO affect as the fireflue is simply a part of the flue system


Important note: Every chimney flue eventually becomes clogged with soot affecting the air flow, and since this soot also 'grows' on the inner section of the fireflue, it causes a restriction of the transmission of heat through to the water jacket and it takes longer to heat up your hot water tank.

Make sure your chimney flue is cleaned every year especially just prior to the onset of winter so that you have a good heat transference and plenty of hot water.!


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