3 way valve replacement

[pandaman]

Could someone please help with 2 queries? 2 weeks ago I had the 3 way valve replaced after it had seized in the hot water position. We had an eon engineer as we had a service contract with them. He replaced the acl drayton valve that had been on since the house was built nearly 15 years ago, with a honeywell valve which he said was a better valve. I have no idea whether it is or not. It works ok but when the hot water comes on there is a 'clonk' from the valve which reverberates round the pipes and sometimes wakes me up when the hot water comes on early in the morning. Is this anything to worry about or could the valve be faulty?
The other question relates to the fact that he had to drain some of the water out of the system before he could change the valve. He used the drain tap situated above and to one side of the boiler downstairs. He ran this untill it stopped. Now I had the whole system cleaned out about May last year due to sludge in some pipes causing hot water to vent back into the f&e tank. Some pipes had to be replaced in the airing cupboard. Obviously I added anti corrosion liquid to the system before filling. How much would this have been lost in this partial draining? The upstairs rads didn't need any bleeding after so would they have lost any water? Is it worth me adding some more anti corrosion stuff to the system?

 

[Garfeild]

Last year i changed about 6 Honeywell 3 port valves that were "clonking"
there was a faulty batch apparently,which move too quickly causing a clonk which vibrates through the coil in the cylinder,and other pipework.
In all cases,swapping the valve for a new one was a complete cure.
Get them back.

 

[pandaman]

Have sent a 'thanks' to you but another thought has come to mind.Can they now change these valves without having to drain down again, I seem to remember from somewhere that with some valves you can do this?

 

[pandaman]

Have sent a 'thanks' to you but another thought has come to mind.Can they now change these valves without having to drain down again, I seem to remember from somewhere that with some valves you can do this?

 

[combispecialist]

he shouldnt need to drain system,popular method with plumbers is to "bung" the system.its where u plug off vent and cold feed to hold the pressure in system thus saving having to fully drain