Product review (1 stars): Works Great/ 2 UPDATES Jan. 3013
I have a history of a recurring problem of the valve malfunctioning every year. The valve manufacturer is some outfit in Wisconsin and they charged almost $100. Sure enough, the valve failed again in one year. So this is the 3rd I have replaced. I will see if it lasts.  One thing I notice is that this is heavier and a bit larger than the OEM valve. It is quieter and has a more solid feel to it. It fit the mounting fine on my Aprilair 440, no problems there. They do not give you a new in-line screen or a flow-reduction fitting, but all I did was turn the tap-in valve from my water source lower and that controls the amount of water flowing into the humidifier, so who needs them and why pay another $10? Works great. Its been 3 weeks and so far working fine. I'm hoping...
I did purchase this from Amazon.
[UPDATE]: This is my second heating season (2013) and this valve is still going strong, no problems with the valve or humidifier. As I said above, this valve is built much heavier that the original factory model. I am very pleased.
[UPDATE]: Finished my 2013 heating season, valve still going strong. I have saved $200 on OEM valve replacements. This is a great item.
[UPDATE]: Finished my 2014 heating season (one of the coldest winters on record), valve still going strong. This makes $300 I have saved on OEM valve replacements. so far. This will be my last update, I think the valve has proved itself.
[UPDATE]: 2015: Valve failed. Working perfectly last winter, turned the furnace off, started 2015 winter heating year and valve will not open.
[UPDATE]: 2016 Valve failed. Started winter heating year (Nov. of 2015): Valve failed. only lasted 1 year. It stuck open, has to be replaced.