Because if it isn’t an air source heat pump system, it will probably be horribly expensive to run?
1 Like
Our house has three floors and we have a free standing 9KW poelle in one corner of the ground floor. On the ground floor the flue is exposed but on the two floors above it’s enclosed in fire resistant plasterboard ducting (on a metal frame!)with a couple of vents on each floor. The uppermost floor has two bedrooms and warm air is drawn into the second one with a fan and ducting in the attic space.
The whole installation was done by a poelle engineer, so I don’t have the details of the fan etc, but the original idea was mine after seeing a cheap DIY system for attics in a French store’s catalogue . It was similar to this:-
If that link doesn’t work try copying and pasting the one below
On my house, 2 floors, we have the register plate above the poelle the flue runs inside the old and large chimney to the second floor. At this point we took down the chimney and rebuilt in the terracotta chimney blocks on a second cast in register plate. That meens there is a lot of hot air trapped in between the two. We core drilled 150mm holes in from either bedroom to allow the trapped heat into the bedrooms. It works far better than I had expected so we removed the ugly old electric heaters.
1 Like
Thank you, so essentially you have created your own vertical ductwork?
We currently have a staircase from the ground floor room with a big Godin stove, and this currently lets warm aair rise and warm the bedrooms.
But I am moving the stairs to a new hallway elsewhere. I could still leave a fireproof grill in place of the stairs, to allow the air to continue to circulate upstairs, but suspect I will require fans to assist distributing warm air further afield.
best wishes
John
Just found this rather more ambitious set-up that you might find interesting
VERY interesting, I wonder what the cost is? The place we’re trying to buy ATM has a mix of oil, wood & electric that I suspect reflects an additive approach rather than following some kind of plan, and I wnder if it might not be largely replaced wit something like this.
Thank you for these pointers to fan/heat exchangers and ducts. Its very much food for thought.
I bought a small cheap multi-duct MVHR unit in the UK (www.boulderdevelopments.com), and the issue of ducts (whether rigid or flexible, and which materials) and duct sizing and positioning seemed to be a black art! There is an interesting debate about this at The great MVHR duct debate. - Mechanical Ventilation with Heat Recovery (MVHR) - BuildHub.org.uk
In addition in more polluted areas there have been grave concerns in highly sealed passivhaus type dwellings of the sealed up ductwork, since it gradually accumulates mould and becomes dangerous to health. So some recommend accessible, demountable and cleanable ductwork!
However we currently need to keep bedroom doors open overnight when it is coldest outside (eg -20) so if I can affordably duct the air from a heat exchanger around our large (250mm diameter double walled) flue it would be a big improvement.
You want good across the room space airflow and based on CO2 and humidity the flow sufficient to achieve this. A good blast woth ozone every now and then will kill mold etc.
250mm diameter double walled insulated or just double skinned?
Yes, I think it’s far far less likely where we are up in the Jura Alps, but still we are talking about something that most people install and forget, and what we do now may still be in use in 50 years time. So I prefer to consider how to inspect, whether to bury under insulation or build in or keep fully accessible at the start of the process.
There is a general discussion of good practice with MVHR ductwork at What puts people off about MVHR systems? Cleaning ducts, airborne viruses and maintenance explained - Heat, Space and Light Ltd (heatspaceandlight.com) “The semi-rigid ducting we use is smooth internally, which will limit dust sticking to the walls. The ducting we design in a radial format is a single length from valve to manifold, so it can be cleaned with a pipe cleaner.”
One of the scariest photos is of a London PassivHaus installation filter, completely clogged after 4 months. Despite the quality of the filter I think some of that has necessarily got into the ductwork beyond. Justin Bere showed this in a presentation some years ago and I have never forgotten it.
Passivhaus air filters in London after less than 4 months | bere architects
I like his enthusiasm, unfortunately even in smooth walled pipe the air or whatever is down the centre, at the edge (wall) the flow is stationary or even backwards so still deposits on the ducting. Regular cleaning is still needed but the smooth surface will help in that respect.
I believe it’s an ordinary electric heating/cooling system. The aircon unit is outside, with a heat exchanger and all the pipes which lead to the different rooms, in the attic.
What you describe sounds like a heat pump ( air source)