May need to drain sown the system to install new motorised s

[mdcarlile]

Hello,

I am currently trying to replace a 3-way motorised return valve to my CH/HW system after a failure of the motor (Siemens). I have searched the internet and local plumbing outlets for a replacment motor so that I can easily swop it over without changing the valve itself. However, there dont seem to be any compatible motors with my valve.

So now I am left with only changing the entire valve and thus need to drain down the system. I have a Siemens CMV322

I would appricate some advice for this.

Do I drain down the radiators via a drain valve using air to push the water out?
Do then have to drain the hot water cylindar to below the inlet pipe level?
Does the pump need to be isolated at the bolier side?


Cheers

Mark


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[Hugh Jaleak]

Turn OFF the power supply to boiler, pump etc. Isolate water supply to the CH system. Attach hose to a radiator below valve level, turn on drain cock. System will drain by gravity, open bleed valves to allow air in will assist. When water stops running close all bleed valves, drain off etc. No need to worry about the cylinder, the water in here is completely separate. Heat transfer from the boiler takes place via a copper coil inside the cylinder.

Replace valve. Ensure wires are connected like for like.

Refill system, ensure valve is locked in manual position. Bleed rads, pump and boiler if required, check for leaks. When all ok, switch on power, allow boiler and pump to run. Check all working ok. Put fresh inhibitor into system.

Honeywell valve would be best buy IMO.

 

[nickso]

bung it.

 

[mdcarlile]

Can you bung a 3-way valve?

Thanks

M

 

[nickso]

yes but the water stops quicker if you close one or both pump valves.