I have an 'Armstrong Astro Express' hot water circulation pump, which has stopped working after 3 1/2 years of service - so I am looking for a replcement. I came across a variety of brands online; so am looking for recommendations. Does any of the following outshine the rest? 1. Armstrong Astro Express (The brand which I was quite happy with, but which died out rather prematurely in my opinion) 2. Watts Premier (Cheapest one available) 3. Grundfos 4. Any other? Another question -- should I also replace the check valve between the water heater and the pump? Thanks!