I have a nine hundred square foot home that has a wood stove as its only source of heat. I am planning to be away for one to two weeks a couple times this winter and am wondering if an infra red heater(claims to heat up to 1000sq ft) would be sufficient to keep my plumbing from freezing. The only plumbing is the kitchen and bathroom and they are right beside each other, so with the bathroom door open the heater could be pointed at both. I have separate heat in the basement. I am also counting on it to run while I am at work.
As mentioned above, putting heat into the pipes is the best way to go. If the pipes are accessible, you might be able to put warming cables (aka frost protection, heat tracing etc etc) on them, on a simple time switch to provide a heat input - these would put the heat exactly where it's needed & use relatively little electricity - rated at 10W/metre for this brand(http://thorneandderrick.com/heat-tracing-cables-systems-videos-protecting-pipes-from-freezing-temperatures/). I just picked that company from a search as it had technical specs.
If you could lag them as well that would be good, to retain the heat, your running costs would be lower still (different manufacturers have differing requirements). If they're boxed in, drawing cable through would still help as the boxing-in would help retain the heat to some extent.
If you put a (any) heat source at a low point in the plumbing, the warmed water will, to an extent, circulate through convection, which could be useful for inaccessible areas.rated at This is a good read... http://inspectapedia.com/plumbing/Pipe_Heat_Tapes.htm
Anything that puts heat into your home has a chance of working. If you want to keep the plumbing from freezing, then the best place to apply a small amount of heat to do the job, would be on the plumbing itself.
Infrared heaters feel warmer than the actual heat that they put out, because our skin picks up the infrared and makes us feel much warmer. But the air temperature can still stay very cold, and it's that that will determine whether or not your pipes freeze.
So as a cost-saving way to stop the pipes freezing, infrared heater won't really work, other than just putting a bit of heat into the room.
It would be much more effective to lag all the pipes (hot and cold) thoroughly; and apply very local thermostatically-controlled heating to particularly vulnerable areas.