Instruct: Classify a review into positive or negative sentiment.
Query: Received two defective units in a row

I ordered the Honeywell 50150 from Amazon on Feb 29, 2012. The unit I received vibrated and pulsed air out of the top. I called Kaz the manufacturer who confirmed this is not normal. Returned to amazon and requested replacement. Second 50150 had exactly the same problem. Returning to amazon for refund. I recently purchased the 50250 from Kaz, and it works fine with no vibration and stable airflow with no pulsing.The problem as I could figure is the 50150 came with a hepa filter that was slightly too tall at 6.25 inches. The housing could not be installed over the base so that it was flush at the bottom like with the 50250. This could be the reason for the shaking and vibration. There was no shaking or vibration if I removed the filter. Or, it could be a problem with the fan vibrating. Hopefully Kaz will fix this, because otherwise this could be a good performing air purifier for the price.