Honeywell Motorized Valves

Hard water is only hard until it is heated and then the minerals precipitate out inot the boiler. And in a closed system, the initial water is the main contributor, since makeup water is a minor factor. If you are replacing motors, maybe you should be checking the valves to see if they are binding and overloading the motors. To get an additive into a closed system, you either have to inject it under pressure or drain the system down to a level where you can pour it into an opening on the boiler.

Most residencial zone valves are GARBAGE. I would opt for a B&G /Armstrong series 100 circulator and use NON Electric Zone valves to fine tune each radiator if your lucky enough to have Cast Iron radiators/ baseboard and a two pipe system .

If you have that cheap copper fin stuff your still better off with a seperate circulator for each zone BUT figure your velocity as to not cause any erosion as hot water above 180 degrees should have a max velocity of 2-3 FPS.

The only way for HARD water to make any difference in your hydronic system is if you bleed the system alot ( not a good thing to do) OR you have some leaks going undetected.

Normally once the water is heated the oxygen is boiled out and any mineral deposits stick to the hottest part of this system (boiler).

If your area is prone to erotic voltage drops/increases AND your zone valves are line voltage this could be a problem. You may want to check your step down transformer to make sure your getting the recommended voltage your valves require if your using low voltage valves actuators.

A loose wire could also account for this type of valve failure.

Before you even think of adding any additives you had better check with the boiler Manufacturer as some chemicals have an adverse reaction to the elastic seals some boilers manufacturers use today
(“O” rings corroded)

If you indeed have hard water that is destroying your zone valves YOU HAD BETTER CHECK YOUR RELIEF VALVE ASAP for proper operation, See ASME section IV for details good luck.

boy that guy gives me a headache! honeywell does sell just the replacement motor for this valve, it’ll save you $$. some of those motors last 15 years and some only a couple, it’s alot cheaper than repiping the whole mess though. i dont have the part# for the motor but if you want it, e-mail me.
jack