Wood Burning Stove Installation

The cost of having wood burning stove fully fitted can run into several thousands of pounds. Not only that, the cost of suitable fuel can cost you a couple of hundred of pounds per winter. One must consider the initial cost and running costs before deciding if it will be worth while. Having said that, when selling a property, a wood burning stove can be a selling point that can ensure a quick sale. Also there is something about us men that love fire! It’s a must for me and for providing an extra heat source to generally warm the rest of the house. As I plan to do most of the work myself and source the best value products, I am pretty sure I can do this under £1500, that’s including a powerful contemporary multi-fuel stove. After this one-off this cost, I will be able to get almost free extra heat for the next 2-3 years as I have built-up a wood supply.

I cannot really understand why someone would pay thousands for a stove, and another few more to have it installed. I looked around in just one show room and they just seemed all over priced to me. I purchased a 12Kw on eBay from Stoveworld just under £480. I had to pay an extra £40 for the Defra version which is approved for smokeless areas. This is the best value I could find for such high wattage. When it was delivered, I was surprised how well it was packed and the build quality is just excellent. I drew up a rough plan in Sketchup below. Note this is not an approved design, just an idea at the moment.

Usually you need a HETAS engineer install it and to provide a certificate. The certificate is a legal requirement as far as i know. Without this if you home insurance could be invalid if a fire broke out. Certain regulations have to be followed if you plan to install it yourself.  I roughly estimated the cost of the stove at £400, Chimney liner and cowl £300 and installation £300. Say £1000 + VAT. After doing some research I realised is it not as simple as that. Also speaking to building regulations i learned that you can infact install it yourself and get them to inspect it. Usually the cost is £140 however as part of an existing extension/build the cost is reduced to a reasonable £50 only if submitting at the same time as a main application. They also state that additional testing may be required. This is a safety test by a HETAS engineer or NACS chimney sweep member that is bascially a smoke test.

 

Scaffolding or Ladders?

I was under the impression the liner could be fitted using roof ladders. This is mainly because someone up the road was getting a liner fitted, so i asked for a rough quote. They said that it could be done using roof ladders. As i decided to work on both chimneys on the property I went for scaffolding. A few years ago year I was quoted £150 per chimney however i paid £375 in 2017 for both. This is slightly less than usual as the scaffolding would be built off the single storey extension roof. The normal price is roughly £250-£300 for each chimney otherwise.

I must stress at this point scaffolding is a must. Your life may depend on it. The height of the chimney is very deceiving from the ground. At approx 10m it is very frightening up there for the average person. Just the wind and slight vibrations make your legs wobble. I have worked on an eves height scaffolding before with no problem whilst helping a friend. On mine, I just could not get myself up onto the scaffolding boards at this height. I found it so uncomfortable the first time, I went out and got myself a full harness with larn-yarn for safety. You have to consider that if you are replacing any chimney pots and removing the flaunching (sand/cement mix) on the top of the chimney, how are you going to get the rubble down and bring a new pot up there one-handed if using a ladder. With scaffolding you can easily use a rope or pulley without any major risk. If you are replacing more than one pot, replacing the flaunching or if re-pointing the bricks the scaffolding is vital.

Product Estimate Actual
12Kw Stove £440 £480 for the Defra version
Flexiable Flue liner £250 £280. I decided the best grade of steel
Chimney Pot £50 £80
Chimney cowl £50 £50
Vitreous Pipe £30 £70 –  an offset type
Liner to Pipe adaptor £30 TBC
Register plate £30 £15 I used cement board instead of a steel one.
Closure plate £20 TBC
Carbon monixide Detector £20  £19.99
Building regs notice £175  Reduced to £50 as part of extension
Installation Test £100 TBC

The Stove

The stove will need to provide a suitable wattage to heat the room that is stated in Kilo-watt (Kw). I went for the biggest one i could afford at 12kw and reasonable size for the chimney breast. I did not do any calculations as this would only be used for a secondary heat source in addition to the gas central heating. If the stove’s output is too high for the room, I could simply turn it down or open the hallway door to heat other parts of the house. I was planning to purchase a stove with a back boiler and run the under floor heating off this however things get very complicated. I have a simple plan to run a circuit from the manifold above the stove to keep the UFH floor warm, however i need to get the stove fully fitted and running before I decide on this route. On my property the inner chimney width is approx 10″ wide, the stove has  flue 6″ that means it will fit nicely with insulation around the liner.

Chimney Opening

I have seen so many images on the internet where stoves have been placed into such tight spaces. This is not ideal as the stove needs to have room to circulate air/heat around into the room. Also they just do not look appealing in tight spaces. When i first removed the old open fire a few years ago, all i did was create a new concrete base, insert a lintel, plaster the sides of the opening using fire cement and skim the face of the fireplace. All this work I did was re-done as a part of the new floor construction and to make room for the wood burning stove.

The Hearth (base)

The hearth must be made of a non-combustible material and the stove needs to be a certain distance away from anything that is combustible (burns) such as carpet, laminate flooring or doors. You also have to maintain a 50mm air gap at the rear of the stove and minimum distance of 225mm from the front face of the stove to the end of the hearth. This must be increased to a minimum 300mm for stoves that can be operated with the door open.  I would have liked to have a black granite hearth to match the front room, however i have seen that ash from the stove shows up on the granite too much. The back of the chimney had old bricks exposed. If i cleaned them up, re-pointed in white mortar, layed the matching bricks as a base, it would produce a really nice feature.

Air vents

For optimal performance of the flue and good combustion, the stove needs a good supply of air. For stoves under 5Kw the air that leaks into the room may be enough. Above 5Kw an additional air vent is required. This is a regulation! If air is restricted, the fumes will not go up the chimney properly resulting in a smoke-filled stove/room. This can be very dangerous. When i constructed my new floor I added a vent into the centre of the hearth using a pipe from the void in the floor. This was approx 50mm in diameter that i belive is not enough. I should have gone for a 100mm pipe at least.  When cold air is drawn through the vent, it is best kept away from the living area otherwise you  will feel the draft. I will have to add another vent in the ceiling rather than somewhere lower down.

 

The work…..

My first job is to move the lintel a brick higher. I can recall that the chimney brickwork had a curved arch brick pattern to act as a lintel before plastering therefore I should be able to do this without any support.

I knocked off the bonding plaster to expose the lintel.

I removed the bricks above the lintel leaving the ones in the middle until i know for a fact the wall above are supporting themselves. Then raked out the mortar around the lintel and checked the brick in the centre did not move. Looks like the wall is supported by the arch under the plaster that forms an invisible lintel.

I raked out the mortar around the bricks where the lintel was going to be moved to. I drilled holes using s SDS drill so I could crack half of the brick out. I was oringinally thinking of 2 brick higher, then i went for 3 to be on the safe side. Later I found out 3 bricks higher would be perfect, that’s 1.2m from the ground.

I placed a bed of mortar around. Notice that i did not place any above yet. Once it has gone off I will pack it with mortar and slate to bear the load of the bricks. This way any hair-line cracks are avoided in the wall/plaster.

I used a level to check it. Perfect. After doing my rough sketch i noticed the flue will not go directly into the stove. There is no space for the collar of the closure plate to fit around it. You have to maintain a 50mm air gap behind the stove as a part of the building regulations. This means I will need an off-set pipe to take the liner/pipe into the stove.


The scaffolding guys came and did a great job. No broken tiles! I can easily work on the 3 chimney pots now on this side

Once i was up there, i noticed how poor condition the top of the chimney was. I would have not been able to complete this job if i hired a cherry picker instead of the scaffolding. This will take be 2 days at least. We had 2 pigeons fall down in 5 years so I planned to cap the unsed pot and fit cowls.

All the flauching need to be replaced and the tiles made good. I started knocking the flauching off using a bolster making sure nothing fell down onto the roof tiles.

Once i removed a pot i had a chance to look down properly. Considering this has been exposed to the elements for 80 odd years the only thing that has saved this chimney from disaster is the strong white pointing on the outside. The stack of the brick that separates each chimney were loose on a few courses. I replaced a couple of bricks on the top course. At this point i noticed the new chimney pots may be too large to go inside like they were before, therefore they will have to sit on the top of the tiles above the bricks like the chimney at thew front of the house.

I re-bedding 2 loose tiles and repointed the edges (4:1 mix with waterproofer). I had some old angle iron lying around that i could use as supports. I cut two lengths and bedded them in mortar inside so they would allow the pots to sit on top.

To work out the length of lner required, i purchased some rope and marked it with a black marker at 1m intervals. I attached a weight and dropped it down the chimney and counted the marks to measure the length. Approx 8.4m. As the liners are sold per metre I will need to order 9m. The extra 600mm will allow me to take the liner to the top of the pot.


I re-pointed the inside bricks as far as my arm would reach. Notice i left a recessed under the bricks . This will allow me to slide the register plate in later.

I ordered the best grade of stainless steel that is 904 grade. These liners are twin walled meaning that they have two layers of steel. The cheaper is 316 grade that is approx 30% less which is not worth it in my opinion. You can only find some that are 904 in the inside and 316 on the outside. As I only intend to do this job once in my life-time I paid the little extra for the best that claim to have a 30 year warranty.

I ordered 5 bags of Micafil Vermiculite insulation to fill the void in the chimney after running the liner. The fact is hot air rises. By keeping the air in the flue hot until it exists the liner at the top will ensure the flue is working at its best. It will suck the fumes out of the stove and stop any fumes leaking out of the stove. Also insulating the flue liner reduces condensation forming and trickling down the liner into the stove.

If it did not insulate the flue the chances are that due to the length of the liner the air will have cooled down near the top effecting the efficiency of the flue.

I planned to re-point the rear brickwork as it looked quite messy near the top. I could not really decide on the colour at this point as i would have to also decide on the pointing on the brick hearth. I had an option for standard brick mortar, white mortar and a lighter brown colour (mixed with lime).

I raked out the pointing using a mortar rake. I took it approx 20mm deep. Once it was raked out i used a steel brush to give the surface of the brick a quick clean.


Before I fit the register plate i cleaned the chimney for the last time. You can see that only loose dust came out. On the left i have a 12mm Hardibacker board. Instead of a metal register plate i will be using this.


I cut the backer board to size using a grinder. I made it a really tight fit into the brick work and over the lintel. Before it fix it into place the hole for the liner will have to be cut.


I marked it central and approx 5mm more than the liner-adaptor. This hole will be perfectly central in the chimney.


I cut a few slots with the grinder using a diamond disc and shaped a round hole into the board.


I smoothed the edges and checked the adaptor has a good fit. If the hole was too big then i would have to fit an extra closure plate. This would be very difficult as i am using a off-set flue pipe.

You can see the backer board in position. Also i added a few long masonry screws to key the concrete into the bricks.


I used a semi-dry mix of concrete. 4:1. I packed it really tight using a wooden battern. If you wet the bricks and lintel first it make a good bond.


The liner must be fitted the correct way. This is so any condensation, soot, creosote etc. runs down the liner into the stove. The liner should have a printed arrow to ensure you get it the right way however it is very hard to see on shiny metal.

Fitting the liner is a really a two-man job. Although it is flexible it does not bend that much. I first tried getting it in the chimney however it kept of curling. I had to take it out and lay it on the lawn where i spent 10 minutes to straighten it out.


You can see this is the most it will bend if not forced. You really need to keep a large radius on the liner to get it down easily without it curling up. You could also pull it up the chimney. In my case it was not possible as the chimney at the bottom has 2 bends.

I attached a nose cone and strong rope to the liner. The rope was 4mm thick. 6mm would have been better. You will need a fair bit of gaffer tape wrapped tightly.

As i was on my own it was a struggle. I managed to feed it down to the bend. I could see the liner from the hole in the register plate however i couldn’t pull it down while feeding it at the same time. In the end i got my misses to pull the rope while i pushed it down from above. I removed the nose cone and cut away some of the liner that tape around it. I did not want the heat burning the glue that was left on the outside. I had to use a large grinder with a metal-cutting disc.

I temporally attached the adaptor. The bend was not perfect. I had to shape it by placing my arm inside the liner. I attached some tape so i can be sure when drilling polit holes for the screws the liner is fully in place.

 

I filled the gap with loads of fire cement, drilled pilot holes and screwed in 3 stainless steel screws. Now the mess is out-of-the-way I can make a start on the hearth and re-point the brickwork.

I cleaned up some old bricks and jet washed them. I had previously worked out all the spacing and this was the best layout i could think of for the hearth. There must be a minimum distance of 225mm from the front of the stove. These old bricks are the same length.

I bedding a header with 1:6 mortar. I could not make my mind up on the colour of the pointing so i left gaps in-between the bricks for the moment. It makes it easier to lay the bricks plumb this way.

The following day once the header was set I completed the rest. Note the followed through the air-vent that was inserted in the middle when the floor was layed.


After some thought of the colour of pointing, i went for sand-cement-lime mix to produce this lighter brown colour. White would have got stained by the ash and the usual brown would have been nothing special.

I re-pointed the back of the fireplace with the same colour. Looks messay however I will only see 50% of the wall once the stove is in.

I had to make the pointing thickness on the hearth more than the usual to keep the building regs size and spacings corrrect. It will be dry and ready for plastering the sides using fire plastering cement in the next few days. Nice rustic-period effect! i’m very pleased with this.

This is the flue connector on the stove. It’s cast iron with fire rope attached. It’s removalable since it can be placed on the top of the rear of the stove depeding how the flue is going to be fitted.

This is the blanking plate that i removed from the top of the stove and attached to the rear of the stove.

 

Moving this stove onto the hearth was difficult on my own. I placed a sheet of ply wood and gradually dragged it into place. Beforehand i removed the metal grate and top plate inside the stove to make it lighter. After all this i learned I could have also lifted the door off too.

I attached the flue pipe to the adaptor using fire cement and fixed 2 screws on each side to secure it. The other end of the flue pipe is in the stove.

I pushed it up and sealed the gap once again using firecement . This will eventually shrink and crack when it dries. I will be sealing it with heat-proof silicon later.