vfrdave Posted October 5, 2019 Share Posted October 5, 2019 I have issues and need urgent help. My shower in bathroom has been tested and works fine on cold and nice piping hot water from thermal store, pressure could be better though. Plumbed sink in (waste only, tap already in wall) and tested the taps and I get cold and only look warm water. When I check shower it is now the same. If I turn cold supply to bathroom off:- - At the sink I get nice piping hot water. With the cold supply off the nice piping hot water also comes when only the cold tap is turned on (mixer tap). - At the shower I also now get nice piping hot water at the shower as well as cold if turned right down. - toilet when flushed is now refilling with warm water. If I restore the cold supply to bathroom:- - checking shower first it seems to be fine - flush the toilet it refills with cold water - run the sink at first it is fine then only look warm at best from warm tap. - retest the shower and can't get the piping hot water. It seems that the cold water is dominant in the bathroom but how is it stopping the hot water. Likewise with no cold water how does the toilet fill with hot. Could it be my basin tap is letting by and water to other outlets taking shortest path. Bathroom supplied via hot & cold 22mm balanced supplies and branched to outlets as needed. I have a bath tap also to match sink tap it is currently untested and just been tiled over! Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 Put a non return valve on the inlet of the TS. Has it got a blending valve on the outlet..? And are there any balancing valves / PRVs..? Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 (edited) @PeterW On the incoming cold to the TS there is a 3 bar prv with a balanced cold to outlets. Outlet from the TS has a blending valve. Both of which are caleffi branded. Edited October 5, 2019 by vfrdave Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 Further update tested the kitchen with bathroom cold isolated and I get nice piping hot water for 5 mins +. If I throw the cold supply valve to the bathroom to on I run look warm after about a minute in the kitchen. Hot supply to bathroom is as cold as cold one so seems to be back feeding the cold to rest of house. I can only assume my tap is faulty or needs some sort of attention. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 5, 2019 Share Posted October 5, 2019 It almost sounds as if cold is mixing with the hot, going the wrong way around the system. Years ago I had this happen with a faulty shower mixer, inside the thing the hot and cold feeds managed to get connected together when a seal failed. This did pretty much what you're describing, as when a hot tap was opened, cold water would flow backwards from the shower mixer. 1 Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 Any chance you can get an NRV on the hot feed to the bathroom ..?? Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 5 minutes ago, PeterW said: Any chance you can get an NRV on the hot feed to the bathroom ..?? Not easily think it would be beyond my skill set. Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 13 minutes ago, JSHarris said: It almost sounds as if cold is mixing with the hot, going the wrong way around the system. Years ago I had this happen with a faulty shower mixer, inside the thing the hot and cold feeds managed to get connected together when a seal failed. This did pretty much what you're describing, as when a hot tap was opened, cold water would flow backwards from the shower mixer. That is kind of where my stressed scatter brain thinking has got me too. Nearly sure it is the bathroom tap unit which conveniently is buried in the wall. Attempting to strip the tap cartridges out but can't get the thing split. This might help explain it dripping for a period after use. It hasn't much if any use as yet. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 5, 2019 Share Posted October 5, 2019 I would guess this might be the hot favourite for where the fault lies. I believe that shower mixers shouldn't be able to do this now, as they are supposed to have built-in NRVs on both inlets. Certainly the one that I fitted to this house had NRVs fitted as inserts as supplied. Not sure about other bathroom mixer taps, though. Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 How do I get these off without damaging them any further Link to comment Share on other sites More sharing options...
Adam E Posted October 5, 2019 Share Posted October 5, 2019 I would say JS Harris is bang on, but not all showers have NRVs fitted especially the cheaper models. Can you remove the shower or isolate the pipes ? I think if you can disconnect the shower pipes and try that Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 5, 2019 Share Posted October 5, 2019 Might be one for @Nickfromwales Ours fits from behind the wall, and luckily I can access it from behind. Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 @JSHarris @Adam E I think my problem is with the tap for the sink rather than the shower. Both however are buried in the wall with no exposed pipework at outlet. Only exposed pipework is close to TS and is the 22mm supplies for each of the various circuits. Sink tap is the easier one to dig out of the wall just not were I want to be when trying to get cleaned up to move in. Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 I wouldn’t bother - If there is 22mm available then a cut and shut NRV will fix it. Don’t wreck the wall ..!! Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 13 minutes ago, PeterW said: I wouldn’t bother - If there is 22mm available then a cut and shut NRV will fix it. Don’t wreck the wall ..!! Correct my thinking but the only exposed 22mm I have is close to TS if I cut and shut it with a nrv it will only protect circuits to other rooms. I will still have the issue in the bathroom as it is a main 22mm reduced and branched to that room. I would need an nrv at the sink or replace the tap unit both needs digging in the wall. Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 Sorry read that as there is a 22mm to each room, not that it was branched Can you get under the floor or in a ceiling ..?? Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 34 minutes ago, PeterW said: Sorry read that as there is a 22mm to each room, not that it was branched Can you get under the floor or in a ceiling ..?? Nothing in ceilings all comes from the floor. The floor has lovely ufh in it so not easy. Bathroom floor is now tiled also so the wall it might have to be. Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 26 minutes ago, vfrdave said: Nothing in ceilings all comes from the floor. The floor has lovely ufh in it so not easy. Bathroom floor is now tiled also so the wall it might have to be. Ok - go quite low, cut a section from the wall with a multi master or something similar and you will be able to patch it back in without too much hassle. I’d basically add a non return valve onto the feed to the tap - doesn’t matter which one as long as it will stop the bypassing. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 5, 2019 Share Posted October 5, 2019 5 minutes ago, PeterW said: Ok - go quite low, cut a section from the wall with a multi master or something similar and you will be able to patch it back in without too much hassle. I’d basically add a non return valve onto the feed to the tap - doesn’t matter which one as long as it will stop the bypassing. Pretty sure you need to either put the NRV in the hot pipe, or both. Putting one in the cold pipe won't stop the problem if it's the cold pushing into the hot, which is what it sounds like. Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 4 minutes ago, PeterW said: Ok - go quite low, cut a section from the wall with a multi master or something similar and you will be able to patch it back in without too much hassle. I’d basically add a non return valve onto the feed to the tap - doesn’t matter which one as long as it will stop the bypassing. 1 minute ago, JSHarris said: Pretty sure you need to either put the NRV in the hot pipe, or both. Putting one in the cold pipe won't stop the problem if it's the cold pushing into the hot, which is what it sounds like. I think I am going to have to pull the tap unit out otherwise I will still really only get tepid water at that tap. An nrv on the hot would sort every other outlet. I just want to sense check my thoughts that the buried tap unit is the issue before I get the cold chisel out. The wall can be patched and tiled over for a nice splashback when we get the proper floating wood shelf for the sink in, Pinterest has alot to answer for. Unfortunately this the bathroom that will be completed to get us in, both ensuites not touched yet. Link to comment Share on other sites More sharing options...
PeterW Posted October 5, 2019 Share Posted October 5, 2019 37 minutes ago, JSHarris said: Pretty sure you need to either put the NRV in the hot pipe, or both. Putting one in the cold pipe won't stop the problem if it's the cold pushing into the hot, which is what it sounds like. Yep correct - my bad !! I would do both. Link to comment Share on other sites More sharing options...
vfrdave Posted October 5, 2019 Author Share Posted October 5, 2019 3 hours ago, vfrdave said: How do I get these off without damaging them any further Anyone know how to slacken these without damaging the chrome. They are only turned onto a few threads just no way to grip them easily Link to comment Share on other sites More sharing options...
ProDave Posted October 5, 2019 Share Posted October 5, 2019 Wet towel (it grips better) wrapped several turns and then gently with a pair of gland pliers. 1 Link to comment Share on other sites More sharing options...
vfrdave Posted October 6, 2019 Author Share Posted October 6, 2019 @Nickfromwales any thoughts on this one, I appreciate you are a busy man but if you have 10mins. WhenI get the cartridges out is there anything to look for specifically or is it a case of dodgy tap gubbins. Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 6, 2019 Share Posted October 6, 2019 56 minutes ago, vfrdave said: @Nickfromwales any thoughts on this one, I appreciate you are a busy man but if you have 10mins. WhenI get the cartridges out is there anything to look for specifically or is it a case of dodgy tap gubbins. Who fitted the TS? Did they use a pressure reducing valve at the cold water inlet, directly before it? Deffo a mixing fault due to missing / fouled NRV's. You could solve this possibly by fitting a whole of house PRedV at the incoming cold mains and set that to 3.5-4 bar. Sounds like you have good cold mains pressure adding to the problem. Getting the cartridges out may or may not allow you to solve the problem, if you cannot get NRV's in there / get to the ones that are U/S. Do you have the manufacturers literature for the basin and the shower units? 19 hours ago, vfrdave said: It seems that the cold water is dominant in the bathroom but how is it stopping the hot water. Likewise with no cold water how does the toilet fill with hot. Could it be my basin tap is letting by and water to other outlets taking shortest path. Bathroom supplied via hot & cold 22mm balanced supplies and branched to outlets as needed. I have a bath tap also to match sink tap it is currently untested and just been tiled over! It doesn't sound like they're balanced to me! Hence the question above about the PRedV. The cold water supply to the bathroom ( any mixer outlet ) should be the same feed that goes into the TS cold side, so if your cold feeds for the bathrooms simply tee off the cold mains then there's your problem. The problem is that the cold feed gets the resistance of the DHW coil in the TS added to its flow dynamic, so it's naturally under-powered vs the cold feed when being drawn at the same mixer ( hence the reference to dynamic flow NOT static pressure ). If all are the same, then you'll need to get to all of them I'd try with the primary PRedV first and see if you're lucky, if that can be easily undertaken on an experimental basis? Link to comment Share on other sites More sharing options...
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