Water Hammer on 2 Port Valve

[FatBob]

Hi

Can someone help please.

I get a massive bang when a two port valve closes.

I have secured the pipes.

It is an S plan and I believe it is the valve that goes to the hot water cylinder. If I turn the Thermostat up on the cylinder and get hot water from the boiler to flow and then turn the stat down I then get the bang at the valve. I tried turning the pump speed down from 3 to 2 with no affect. I contacted honeywell and they said it was differential pressure. I then started looking at the Auto Bypass valve. This looks as if it has been installed correctly between the flow and return set between .2 and .3 mb. The valves have been installed under the floor boards in an inaccessible place. The system has a close vented cylinder in the garage but has an open vented cylinder up stairs. A two port valve goes to the cyclinder in the garage then the 2 ports valves for the ho****er are upstairs and one for the heating.

I found on the internet someone said take the short spring out of the zone valve so it is slower at closing. On this web site someone has suggested that I use a Myson 2 port valve which is not so prone to hammer. The other option is to use a water hammer arrestor. I have had this problem since moving into the property. Is there anything that I can do with the Auto Bypass valve. Thanks for any help. FatBob

 

[SimonG]

Auto by pass.

 

[Chalked]

Welcome.
It will be fitted the wrong direction. If you drain down, undo the compression nuts and turn it the other way around.
That should cure it.

 

[PhoenixServices]

Got the same thing happen on both my Honeywell two ports at home. First the hot water one a year ago then the other week. Auto bypass set up up correctly.

 

[FatBob]

Got the same thing happen on both my Honeywell two ports at home. First the hot water one a year ago then the other week. Auto bypass set up up correctly.

I must be honest I really don't know how to set up the Auto Bypass valve properly, obviously I know how to turn it but do not know the best setting to put it on.

I have Grundfos UPS 15-50 130 in front of the valve.

I am confident that my two motorised valves are in the correct direct as they point in the same direction H/W and C/H. The arrows both point in the same direction.

FatBob

 

[Last Plumber]

I've Just had a customer with a three port Honeywell banging on changeover in either direction.
Never seen it before on a three port.
not looked into it yet. Anyone else seen that?