Expert: Dan Griffin - 6/1/2008

Question
Hi
I live in Yorkshire England.  we have a small conservatory type building extended on the side of our house, it is constructed of brick but has large windows on 3 out of four sides and a poly carbonate roof. it measures approx 9ft long by 6ft wide.  

I keep exotic pets for which the correct temperature maintenance is essential.  Although heat is not often a problem in England (unfortunately) on occasion it can become extremely hot in this room.

I have been thinking of ways to manage this occasional temp increase and have thought about possibly using an extractor vent (as used in bathrooms) placed towards the top of the room to help expel the excess heat.

Firstly do you think this may work?? and if so would it be possible to wire a room thermostat in with this so it only comes one when needed??  Or do you have any better ideas??

thanks
james

Answer
James, when you described the room, I was sure it was what we call a green house designed to grow flowers,etc., especially when you said the panels were polycarbonate.  A green house here would be designed to open a section of the top to adjust humidity and temperature for the plants.

Your intent to add ventilation would be a great start.  There will be noise, but you can watch the sone rating.  I would think you would want aa  large,slow fan.  If you can exhaust through the sidewall it will save a potential roof leak.  The fan must be able to draw an equivalent amount of intake air which is usually done with a sized louver.  YOur winters will demand closing off these draft holes which leads to operable louvers at both supply and return or manual shutters of some ttype.  Yes, the whole system can be controlled by temperature, unless you go with the manual shutters.  This is not a refrigerated system, so the ultimate temperature will be some bit higher than the outdoor temperature unless you incorporate a swamp cooler or refrigeration.  I have no idea about your local supply houses or trade designations.

Here, I would suggest an HVAC contractor and/or supply house.  Here is a US source:
Fan:
http://www.grainger.com/Grainger/wwg/productIndex.shtml?L2=Exhaust+Fans&operator...
Intake louver:
http://www.grainger.com/Grainger/wwg/productIndex.shtml?L2=Exhaust+Fan&operator=...
Control switches:
http://www.grainger.com/Grainger/categories/hvacr/controls/line-voltage-thermost...