steveoelliott Posted August 28 Share Posted August 28 Hi, I have purchased 2 x GROHE Flushing Cistern Solo 0.82 M 38691000 I am pleased with them for the most part and they replace existing Grohe cisterns that were in place for 14 years prior. However, these new ones appear to shut off the water supply very quickly after filling. Whilst the rapid shutoff does not cause our pipes to bang, I wonder if the abrupt shut off may cause issues further down the line. Is there a way to adjust the shut off so it does so more gradually? I have attached a video. Thanks in advance... IMG_4227.MP4 Link to comment Share on other sites More sharing options...
marshian Posted August 28 Share Posted August 28 A - Restrict the feed with an isolation valve? B - Add a small length of capped pipe vertically before the cistern connection - creates a pressure absorber with no mechanical parts to worry about Upstairs in my house the toilets are all gravity feed so no issues with shut offs causing pipe work noises - downstairs I have one on mains pressure I tried A but it was still filling very quickly and causing pipework noise so I did B and that made the pipework silent 1 Link to comment Share on other sites More sharing options...
Alan Ambrose Posted August 28 Share Posted August 28 Sounds like a tiny amount of water hammer. Agree with above. Problem may go away as the valve gets furred up. I have this problem too (I must fix it someday ) - caused I think by high mains pressure - it's 4 bar here. There's also an off-the-shelf version of B above - look for water hammer arrestor or similar. Just possible it's also related to the expansion tank - either the diaphragm going or set at the wrong pressure - so it's not absorbing any fluctuations. 1 Link to comment Share on other sites More sharing options...
steveoelliott Posted August 28 Author Share Posted August 28 2 hours ago, marshian said: A - Restrict the feed with an isolation valve? B - Add a small length of capped pipe vertically before the cistern connection - creates a pressure absorber with no mechanical parts to worry about Upstairs in my house the toilets are all gravity feed so no issues with shut offs causing pipe work noises - downstairs I have one on mains pressure I tried A but it was still filling very quickly and causing pipework noise so I did B and that made the pipework silent I could technically do A simply by slowing the flow in the valve in the toilet. There is a valve on the inside of the cistern. That said, if I have other taps running, you still get a thud, just less of one. Interesting idea re capped pipe, I have seen similar hammer arrestors that are made for this purpose. Link to comment Share on other sites More sharing options...
steveoelliott Posted August 28 Author Share Posted August 28 1 hour ago, Alan Ambrose said: Sounds like a tiny amount of water hammer. Agree with above. Problem may go away as the valve gets furred up. I have this problem too (I must fix it someday ) - caused I think by high mains pressure - it's 4 bar here. There's also an off-the-shelf version of B above - look for water hammer arrestor or similar. Just possible it's also related to the expansion tank - either the diaphragm going or set at the wrong pressure - so it's not absorbing any fluctuations. Yes, probably is water hammer but the pipe work is secure enough for it not to bang / knock. The question really is as to whether this matters? Presumably, this is putting strain on connections / joints etc. Pressure here is 2-3 Bar. Like you say, as the valve ages, it may change the behaviour. No expansion tank on the cold side, just on the hot for the unvented cylinder. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted August 28 Share Posted August 28 (edited) >>> No expansion tank on the cold side, just on the hot for the unvented cylinder. Good point, but I think as they're linked through the HW cylinder, they should get roughly the same pressure variations. Mine hasn't mattered for a year or so , but I'm thinking I should get round to it. Edited August 28 by Alan Ambrose 1 Link to comment Share on other sites More sharing options...
steveoelliott Posted August 28 Author Share Posted August 28 7 minutes ago, Alan Ambrose said: >>> No expansion tank on the cold side, just on the hot for the unvented cylinder. Good point, but I think as they're linked through the HW cylinder, they should get roughly the same pressure variations. Mine hasn't mattered for a year or so , but I'm thinking I should get round to it. I contacted Grohe over the weekend, who have just now responded saying they will send somebody round to have a look at it. Guess it can't do any harm. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted August 28 Share Posted August 28 Wow! Let us know how it goes. Link to comment Share on other sites More sharing options...
steveoelliott Posted September 4 Author Share Posted September 4 Engineer from Grohe came and said this is perfectly normal. Apparently the way in which they shut off is instant and it isn't going to cause any problems. He took the static pressure as one of his checks, came back at 3 bar. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now