Hot water taps suddenly running very slow upstairs only

JanK

New Member
On Sunday 22 September in the morning our upstairs bathroom taps were running normally (we have excellent water pressure in our area). In the evening I tried to use the hot water taps and it was as if the water had been turned off at source. In fact I assumed Thames Water had turned off the supply somewhere locally which has happened on the odd occasion. However both upstairs cold water taps gushing normally. Also the Vaillant combi boiler located in kitchen was making a sort of whooshing noise it never usually makes when either of the bathroom hot taps are turned on (sounds a bit like the noise a kettle makes when first turned on). We assumed the problem was caused by boiler fault and called boiler service. The guy came round and didn’t even open boiler and said it was water pressure and left, didn’t believe him and called them out again, second guy said the same thing or that we could have a leak. Called Thames Water and the guy said definitely nothing wrong with water pressure (which we knew ourselves as upstairs cold water taps gushing normally) and he said definitely no leaks. We called a plumber and he didn’t seem to know what the problem could be. My husband took upstairs bath tap off and poured lime scale remover down pipe but it continues to run really slowly as if there is some blockage. I’m still not convinced it’s not a problem with the boiler. If it was scaled up pipe how can it happen so quickly…surely the taps would gradually run slowly and not suddenly? All heating and downstairs taps running normally. Anyone got any ideas?
 
On Sunday 22 September in the morning our upstairs bathroom taps were running normally (we have excellent water pressure in our area). In the evening I tried to use the hot water taps and it was as if the water had been turned off at source. In fact I assumed Thames Water had turned off the supply somewhere locally which has happened on the odd occasion. However both upstairs cold water taps gushing normally. Also the Vaillant combi boiler located in kitchen was making a sort of whooshing noise it never usually makes when either of the bathroom hot taps are turned on (sounds a bit like the noise a kettle makes when first turned on). We assumed the problem was caused by boiler fault and called boiler service. The guy came round and didn’t even open boiler and said it was water pressure and left, didn’t believe him and called them out again, second guy said the same thing or that we could have a leak. Called Thames Water and the guy said definitely nothing wrong with water pressure (which we knew ourselves as upstairs cold water taps gushing normally) and he said definitely no leaks. We called a plumber and he didn’t seem to know what the problem could be. My husband took upstairs bath tap off and poured lime scale remover down pipe but it continues to run really slowly as if there is some blockage. I’m still not convinced it’s not a problem with the boiler. If it was scaled up pipe how can it happen so quickly…surely the taps would gradually run slowly and not suddenly? All heating and downstairs taps running normally. Anyone got any ideas?
The only thing i can think of that is sudden and limescale broken related plumbing is the mechanical switches that open/close for your heating, they open and close according to the timings for your heating. Those would just stop working and not gradual thing.

Just not sure if you have those for the hot water as well.

Quick search also mention some hot water systems have paddel valves. Good at measuring the water pressure. Like any moving part prone to foreign objects/limescale causing issues.

Not by any means an expert in plumbing but may point you in the right direction and hopefully someone with more knowledge on here can chime in.
 
How many hot water taps are not working ? Is the problem such that no water at all is flowing from them ,or water is flowing but it's just not hot ?
 
How many hot water taps are not working ? Is the problem such that no water at all is flowing from them ,or water is flowing but it's just not hot ?
Thank you for replying Terry. It’s only the upstairs bathroom…so sink tap, bath tap and shower all running slowly but still getting hot water…when you first turn the tap on there is briefly a bit of a decent flow albeit not what it was but then it gradually runs slower and slower until sometimes more of a trickle. When my husband disconnected the bath tap and poured limescale remover down the pipe he was able to pour half the bottle in until the pipe was full to the top and left it there for a couple of hours. He’s going to try it again by this time disconnecting bathroom sink tap and leaving in the limescale remover for at least four hours. Obviously both hot taps and shower are connected to same pipe.
 
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The only thing i can think of that is sudden and limescale broken related plumbing is the mechanical switches that open/close for your heating, they open and close according to the timings for your heating. Those would just stop working and not gradual thing.

Just not sure if you have those for the hot water as well.

Quick search also mention some hot water systems have paddel valves. Good at measuring the water pressure. Like any moving part prone to foreign objects/limescale causing issues.

Not by any means an expert in plumbing but may point you in the right direction and hopefully someone with more knowledge on here can chime in.
Thank you for replying CBE…the upstairs radiators are getting hot. I think what you are suggesting would be connected with a boiler issue wouldn’t it?
 
Are you sure your boiler is a combi ? What is the exact model ? Do you have a hot water cylinder ?
Hi Terry Mac, yes it is definitely a combi boiler…no we don’t have a hot water cylinder. It’s a Vaillant sixteen years old and always been super reliable. We had another plumber come couple of days ago and he was very knowledgeable (after he and my husband poured limescale remover down bathroom pipes after removing taps - didn’t solve the problem) and said it was heat exchange plate and we made another call to boiler people and a guy came around today and after being here for about an hour testing water flow etc he said he would order heat exchange plate and aqua sensor and come back on Monday to fit. Honestly to think we are paying these people over £300 per year boiler insurance and it’s very hit and miss as to whether you get a knowledgeable guy or someone who seems to know nothing. We had the exact same problem beginning January 2023 and it was heat exchange plate.
 
If the problem was with a heat exchanger ,I fail to see how only some taps are affected and not all of them. The boiler can't decide to reduce flow to certain taps ,whatever reduced flow is leaving the boiler can't miraculously increase to certain taps.
 
Hello Terry, thank you for your comment. The problem has been solved. We had a new Vaillant boiler installed which cost around £2600…turned on the upstairs hot taps and hey presto…still running at a trickle! We then got a plumber who removed the ceiling in our dining room (under the bathroom) to get at all the pipe work. For some reason the builders who reconfigured our bathroom 16 years ago chose to use lots of isolation valves here and there with no way of getting to them so we thought one of those was causing the issue. He changed the pipe work and got rid of all the isolation valves and put new ones in the cupboard under the bathroom sink where we can get to them. However the upstairs hot taps still ran at a trickle. The plumber then lifted the carpet and floorboard in the dining room (which is where the original kitchen was) and found a small tap on the hot water pipe under the floorboards and replaced it with a continuous pipe. Finally the upstairs hot water taps are gushing again. It’s been a nightmare…when the guy pulled out the ceiling it was plasterboard over old lathe and plaster so the dust was unbelievable. We’ve had the ceiling done and replastered and now I’m going to paint the whole room after putting caulk around the edge. You could say we wrecked the ceiling for nothing but actually there was a very small leak up there so not entirely a waste of time. The plumber cost £1300 for two days and the guy who did the ceiling and replastered it cost £600 including materials, so the whole issue cost around £4700. It turned out nothing was wrong with our faithful old Vaillant combi boiler and the new Vaillant is a condensing boiler so a lot of steam going off outside which sets off the security light but it is nice to have a proper shower and the bath fills in less than five minutes instead of half an hour!

Thank you for taking the time to give your advice..I appreciate it.
Jan
 
Thanks for coming back to tell us ,that's quite a story. Quite odd that the " small tap" found under floorboards suddenly reduced the flow. Was it blocked with something ,did you keep it.....just very curious ?
 
Hi, no we didn’t keep it. It looked exactly like an old stopcock. It was black and old looking and we just assume that whatever made that stopcock turn off inside must have broken somehow causing a partial blockage thus causing upstairs hot water to trickle instead of gushing. As soon as they removed it and replaced with straight piece of pipe the hot water upstairs was fine. I really have no idea why any plumber would put such items in places which are not accessible!

A plus with the new Vaillant boiler is it’s almost silent.
 
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