Wood stove

oldholloway,

Last week was quite eventful. Mike’s team finished the tin roof, started with installation of airtightness membrane to underside of roof structure and we had a wood stove installed.

Being a passivhaus with low space heating requirements, our house won’t need much heat to keep it comfortably warm, so putting a wood stove in is a bit of a luxury rather than necessity. The intention is that it will provide bulk of the space heating, topped up with towel rail in bathrooms. For simplicity, we have not coupled it with back boiler to heat water (hot water will be generated via heater with air source heat pump). There have been a couple of technical challenges to overcome – airtightness and air supply. We have used Morso S11-42 stove (with optional airtightness kit) in combination with Poujoulat Efficience triple wall flue to give us a completely room-sealed system. The external cavity of the flue supplies fresh air in from outside directly to the stove, and the inner flue takes the hot air out. This ‘pipe in a pipe’ system also means that there is only one penetration through the building fabric. The flue came with a proprietary airtightness plate with a flexible seal, the airtightness membrane will be taped to it.

It was exciting to see the first fire lit – installation crew from Poujoulat (flue) and Prince&Pugh Knighton (stove) did a great job. Will just have to be careful with keeping the fire under control with all that exposed straw inside!

We will be opening the house up as part of international passivhaus open days on 11 and 12 November – follow this link for more information.

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Wood stove

10 thoughts on “Wood stove”

  3. Hi, which diameter of flue did you use, we are looking at the same setup for our passivhaus but concerned about the size of the flue in relation to the stove. The S11-42 has a 125mm diameter outlet and is DEFRA approved so I think should be ok with poujoulats 130mm flue (230mm outside diameter). I also would be interested to know how much you use your stove. Regards Simon

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  4. Hi Simon, I would recommend you get Poujoulat to provide full installation drawings for your setup, that way they take design responsibility for the system. We haven’t used the stove this heating season yet, but once the internal temperatures go below 18C we’ll use it every other day for an hour or two on average.

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  5. mark says:

    I am really interested to hear how you manage to avoid smoke ingress into the room when refueling the stove etc? We have a stove in our (currently non passiv) house and this is a big issue especially when the draw from the fire hasn’t properly established. Maybe different stove designs are less susceptible to this issue? Or maybe your flue is playing a big part? thanks

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    1. Mark, we don’t tend to get significant smoke ingress into the room, occasionally there a bit of smoke at the beginning before the flue heats up and creates a natural draw. I’d recommend getting a HETAS approved stove & flue specialist to design and commission the system to minimise risk of smoke ingress.

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  6. mark harrison says:

    George did you check if the S11-42 is DIBt tested when you arrived at your decision to instal? If it hasn’t been were Morso able to satisfy you that the door seal would be up to the equivalent airtightness standard? Thanks

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    1. We are planning to install a Morso 6143. We found it difficult to get details on Morso stoves DIBt certification but when we discussed with our local dealer they checked with Morso and confirmed that the 6100 series are DIBt tested. They also noted this standard is no longer applied in Germany.

      I still debate whether we should install it at all but I’m taking the view if we have power outage or a heat pump breakdown then to have the flexibility of the stove is sensible. I suspect we will rarely use it.

      Simon Bell

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