I have a Water Furnace Series 7 that was installed in 2015 and worked flawlessly until last week when I had an error code #16 which indicated a variable speed pump failure. This was confirmed by the technician and they have ordered a new pump for replacement. He also found out that my AUX heat unit was causing a loud buzzing due to stuck relay (we never have needed aux heat so this could have been a problem for years) so that is being addressed as well. I was surprised that the pump would fail only after 4 yrs... is this the typical lifespan or did I just have some bad luck? I'm not too concerned this round since it is a warranty replacement but once I get past 10 yrs this part could become a "consumable" which makes me wonder... how easy is this to replace? Is this just a swap out or do is the procedure a more labor intensive (e.g., depressurize the loop)? Thanks!