Clamp On Ammeter

I would like to measure the current being used across my modulating furnace's gas valve. The furnace manual shows that the servo in the gas valve can be measured in milliamps(72 to 180 ma).

I thought the ardruino would be a good way to log the data over time.

I'd like to use a clamp on ammeter since i would not need to cut any wires but so far I have not found something that works with arduino. Any suggestions?

Do you know if the current to the furnace servo is AC or DC? Do you want to log the time the furnace is ON? If it is AC you can get a cheap clamp-on sensor like those used for power monitors in homes. The current is small and you may need to make several loops through the clamp-on to get enough sensitivity. Hope you have slack in the wire!

JaM

My guess would be that the servo is DC. From googling, measuring that might be a bit complicated.

I'd like to log whenever the valve's amperage.

Hmmm, well I've definitely seen hall effect based current probes (clamp around the wire) for oscilloscopes. Googling around a bit I came across this product, might be of interest? http://www.seeedstudio.com/depot/electronic-brick-electricity-meteranalog-p-471.html

The furnace manual shows that the servo in the gas valve can be measured in milliamps(72 to 180 ma).

That is a very small current for a clamp to detect, it requires a lot of low noise amplification which equals expensive.