Two flues into one??

[Alycidon]

Because you have created a circulation loop, whilst the vast majority of the flue gases will go upward if one stove is cooler and in a cooler part of the house than the other a thermosyphon will develop, hot gas will rise to the junction be cooled and then descend into the colder place. I imagine fluctating wind could exacerbate this.

 

I was once called out to a recent AGA installation which tested OK with smoke matches but would not start drawing in the requisite time. I had been asked to fell all the adjacent trees, on the Aga installer's suggestion. I declined the job and explained the what I thought was the reason for the problem. It was a large high ceilinged 2 storey house with a single storey annexe for the kitchen. Largely open plan, recently renovated and gas centrally heated. The chimney in the main room rose through the two storeys and exited above the high pitched ridge. The flue for the Aga used a similar brick chimney but exiting the single storey roof some 3 metres lower. The aga had been intalled without a dedicated air supply to make it room sealed and the house was no longer draughty, with new doors and double glazing.

 

So a mixture of the hot house evacuating air up the taller chimney and a thermally massive chimney to get warm enough to draw combined to stop the aga getting enough air.

 

I had worked in the grounds and delivered logs to the previous owners for about 20 years, I never heard from the new owners again. I still haven't checked if it is possible to install Agas room sealed.

 

The thing about building regs for solid fueled devices is they have to take into account the variability of fuel, modern gas or oil heaters simply won't work unless fed a fuel they are designed for but people bung all manner of rubbish in stoves and open fires and it is important to vent the combustion products well up and away from air the occupants breathe.

 

Any wood or solid fuel appliance of 5.1kw or above requires an air vent, if installed into a newish property that is air tightness tested then all solid fuel appliances require an air vent. Some stoves are now fitted with connectors to attach to an air supply pipe connected to a dedictaed air vent thereby preserving the air tightness of the property.

 

Building Regs stipulate that a flue existing from a single story extension or similar be at least 2.5 meters from the taller property, or the flue has to exit at the height of the main property.

 

Sounds like the AGA was not installed by someone who knows what they are at and it sounds highly likely that is had not been signed off as safe to use. Not unusual these days I am afraid.

 

A