I know how they work thanks, even installed one before I found I could buy an equivalent trade and install it myself (all in the thread somewhere) - SmartVent. I don't sell them, just don't like misinformation.
Heating your house cost more than 1 oil heater - seems you opted to have one installed in your roof. Just don't forget the cost of running it :-)
Heating your house cost more than 1 oil heater - seems you opted to have one installed in your roof. Just don't forget the cost of running it :-)
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