I bought one of these from ChimneyHeaters.com . I installed and it works fine. Heats my 2000 square foot house. I have the pump connected to a UPS but I am not sure how long the pump will run if the electric goes out. I had it installed all winter and did not have to turn on my Electric heat once which saved me about 200 euro a month here in Romania.

The Electric is not stable here so I had to rush to take out the fire a couple of times because the water pump had stopped and the pressure valves were going off. The UPS will solve that but I dont know how long a UPS will keep my central pump going.  I will attach a pic of what chimney heaters are in case you are not familiar with them. The pump is a Grundfos and has three speeds.