I've just had a Worcester Greenstar boiler fitted to replace my old Ideal Minimiser SE. The old boiler did not has a pump run-on requirement and so bypass was fitted. This Greenstar does require pump run-on and so a bypass was fitted. But now, when the last zone valve closes with the pump still running there's a water hammer thump as the outlet pipe from the boiler shakes and hits the inlet pipe. I guess a brace between the two pipes would help, but it won't stop the water hammer. Is this a normal phenomenon with pump run-on boilers?
Water hammer due to zone valve closing
- Thread starter u33446z
- Start date
Sponsored Links
- Joined
- 19 Jul 2007
- Messages
- 5,941
- Reaction score
- 1,139
- Country
No.
We had this with the Y valve on our system so I changed it and on dismantling the valve could find nothing wrong except that the arm, which moves the rubber ball to close the two ports, had a little slop in its action, which would explain the thump we occasionally heard. I wrote to Honeywell who asked for a photo of the installation, which I sent, to receive the reply that the valve had not been installed correctly. They told me there should be a clear run of 100mm of straight pipe each side of the valves and they waffled about turbulent flow in the water caused by the 90 degree bends being too close. I found this hard to believe so despite being tenacious when complaining to manufactures, I gave up. Now, two years later, the new Honeywell valve is beginning to thump as it activates. I expect it will annoy me enough that one day I'll drain down and fit a new one.
- Joined
- 26 Aug 2016
- Messages
- 6,833
- Reaction score
- 1,010
- Country
Can you turn down the bypass to open earlier? If that fails check the valve is installed correctly, and consider moving the bypass to where the zone valve is.
The pipes should be clipped securely regardless.
Sponsored Links
your installer has mixed up the flow and return and your zone valve is now the wrong way round
I’m intrigued. Is there a wrong way round, then?
H
Hot&Cold
Have the installer been informed ?
yes
How should the valve be oriented relative to the flow direction? I didn’t see any reference to that in the leaflet that came with the valve.
There is no mention of the 100mm straight pipe requirement in any Honeywell documents.
- Joined
- 25 Aug 2008
- Messages
- 5,776
- Reaction score
- 2,929
- Country
What he said.
Check the arrow on the valve and make sure the heat is going in that direction.
Thanks all for your suggestions. The zone valves have indeed been fitted the wrong way round
H
Hot&Cold
typical diy install fook upThe zone valves have indeed been fitted the wrong way round
They wont have been fitted the wrong way round , they were probably the right way round, then when your installer fitted the new boiler they swapped the flow and return around as it was easier for them so now the zone valves are the wrong way roundThanks all for your suggestions. The zone valves have indeed been fitted the wrong way round
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
