Fancoil units water flow controls

It depends on what you mean by 'ordinary' !

An 'ordinary central heating valve' would be ok...

But an 'ordinary washing machine valve' would not...it would probably overheat as it isn't designed to be ON for long periods.

Solenoid valve just goes on & off. There will be water hammering at every off cycle.

This you try practically with a pressure gauge on the outlet you will notice the gauge going up nearly 100% + at every off cycle.

Motorized valves are slow opening & slow closing. If auto does not work you switch to manual but the opening/closing function remains the same.

Yes you are quite correct! Water hammer is THE issue. Solenoids are used in small appliances for feed water with little consequence, because they're inexpensive, definitely would be a problem on a fan coil.

A motorized valve may also be used as a proportional control, allowing a full range of flow rates.

Very true but his question is only on the valve and I presume he wants to operate with a manual switch because his auto may not be working.

What really bugs me is that all of them suddenly dissapear and do not have the courtesy of thanking .

Thank you all for the valued input. I am grateful that the feedback has enabled me to tackle an urgent issue where an a/c contractor hired to overhaul room fan coil units has been convincing the services consultant that ordinary soleniod valves are a good option to motorised valves and the consultant seems to go with the contrator's idea as they are late in delivering the motorised valves for a project that has already started. The solenoid valves are to be fitted for room fan coil units for a hotel's guest rooms. Currently, we have motorised valves. There are also plan to replace the room temperature control thermostats as a part of the project. Your valued input has been great help.

In the HVAC industry, the three choices for common zone valves seen on all kinds of equipment are the little Honeywell or ECW valves that have a small motorized head connected to a rubber globe that opens or shuts off the ports. Many of them have a manually open lever to ....manually open it if it burns out and you need flow.

The next common style are the TACO "heater-head" style that are slow acting and use a lot of 24v power, but their longevity is about as good or better than the Honeywell.

Then there is a lesser known style AUTOMAG valves which are true solenoid valves using DC voltage. These are probably the longest lasting valves, they're quite popular in eastern US and applicable with baseboard heating but I've not seen them used on fan-coils. In your application, water hammer might not be a problem.

If the contractor wants to change them, he probably has a personal preference for the other style, if they work OK and the price is reasonable...no problem!

I am totally agree with you. but in case that partial opening for certain flow rate, I think we can not achieved by using the solenoid valve.