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Low running hot water from all hot taps. why??

View the thread, titled "Low running hot water from all hot taps. why??" which is posted in Bathroom Advice on UK Plumbers Forums.

R

rui7

Hi,

We have three bathrooms upstairs. All the sinks have uni-taps (runs both hot & cold water). The cold water flow is fine but the hot water from has been decreasing steadily over the past year. The showers hot and cold water flow is working fine.

We have a cold water storage tank in the loft and and copper cylinder tank in the hot press. The hot water is fed off the top if the cylinder tank.

Im presuming theres a separate pipe feeding off the cylinder for the showers and the problem lies with the pipe thats feeding off the cylinder for all the hot water taps upstairs and downstairs.

I dont think theres a problem with the taps themselves as when I first turn on the taps the flow is fine but then slows down. This suggests theres nothing wrong with the taps and the problem lies somewhere within the piping from the sinks back to the cylinder tank.

Am I right in saying the pipes could be coated with scale/sediment and thus reducing the flow of hot water or would it be something stuck within the piping? What are the remdedies and would this be an esy job to fix (DIY)??

Thanks,

Rui
 
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At the spout of your tap you should find a thing called a aerator, which is a an attachment threaded onto the tap where the water comes out. There is a fine mesh filter on each one which catches all the sediment and dirt that comes from your storage tank and eventually reduces flow from your hot tap. You need to loosen each one to each tap with a adjustable spanner and give them a good clean. Some taps just have the mesh filter and this can be unscrewed by inserting a fine screwdriver into its edge and turning it.

You should flush out your pipework with mains water but it's best to get a plumber to do this. Cleaning the filters will make a big difference. One of my customers had the same problem and I found pipe lagging that had fallen into the tank on her aerators!
 
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Hi,

Yeah I can work a spanner. I replaced the element in the cylinder last year so familiar with the cylinder.

Should there separate feeds off the cylinder tank for the taps and shower?
 
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Hi,

thanks for the reply.

Ok, I havent tried that yet. I will give that a go. I just presumed the because the hot water flow from the shower was fine that it wouldnt be sediment and maybea blockage in the piping connecting the hot taps to the cylinder.
 
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just thinking, theres only one tap for both the hot and cold flow so it couldnt be the aerator because the cold water flow is fine from every tap.
 
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Could be mains, we have a fairly big cold storage tank up in the loft which is definitely used to fill the toilet cisterns as when a toilet is flushed you can here the tank in the loft start to fill again.

So it still could be the aerators in the taps then?

Any idea on how to open up one of them uni-taps (probably wrong name for them)? I took a small cap off one of them but theres nothing to unscrew.
 
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quick way to test for tank or mains fed taps, put your thumb over the spout and turn the tap on. if you can hold the water back it's tank fed and if you get soaked it will be mains.
 
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rui7 said:
just thinking, theres only one tap for both the hot and cold flow so it couldnt be the aerator because the cold water flow is fine from every tap.
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The hot is tank fed via your cylinder, the cold feed is most likely mains fed or it's fed from a separate supply from your tank. Both hot and cold get mixed at the tap outlet. You have a blockage and may need to flush out pipework, cylinder and clean out your storage tank depending on the severity of the blockage.
 
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its tank fed so, i can hold back the water. also, managed to get the aerator off and there was no blockages there. water flow on hot side still dribbling out.
 
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yeah took the aerator out and not blockage. just tried one of the hot taps. the hot still flowing out very slowly with aerator off.

cold is tank fed from the loft.

the fact that the shower is working fine, would that narrow down the possible pipe work thats affected?

Hot water causes more limescale than cold. Could it be that the internal of the hot water piping has scaled up?
 
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You will need to flush out your pipework. Connect your cold main washing machine hose to the hot washing machine valve under your sink, open a hot tap upstairs and flush it through.
 
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So are you saying to swap the two hoses on the back of the washing machine? because the hot tap is also running low downstairs could this mean to a low amount of water entering the washing machine = possible damage to the machine?

just one other thing I noticed. When i went into the hot press to turn off the hot feed using the red wheel I noticed it was very difficult to rotate and I dont think I was able to rotate it with alot of force. I also noticed there was scale build up around the joints of the pipework.
 
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where would that be located? When I tried to shut off the hot feel in the hot press using the red wheel I couldnt rotate it even with alot of force and I noticed scaled build up around the pipe joints at that junction.
 
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no not to swap the hoses, close the two taps where the hoses connect to and remove one hose from the tap end and the other from the washing machine end. join the two taps together with the hose just taken off the washing machine. first open the hot tap then the cold tap for about thirty seconds, then close both taps and see if flow any better from problem hot taps.
 
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Is the valve on the hot feed still jammed?

The trick on the washing machine feeds is to disconnect the washing machine then use one hose to link the hot and cold together.
 
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yeah its still jammed.

Is connecting the cold to the hot just a way to flush out the pipe work? If the flow is still restricted after switching the cold to the hot would this indicate a blockage somewhere in the hot piping?
 
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Ok, so your using the high cold water pressure to flush the hot water pipe network out.

If this doesnt remedy it, then how would you pin point the problem pipe so to speak? Is it a cases of having to replace all the pipes involved?
 
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As i said in my first post disconnect the fitting coming out the top of the cylinder and pull the pipe to the side. Your problem is likely to be scale build up at that fitting. You can poke it off but it should really be changed for a DZR one.

You will need to turn the hot water off to do this. If your valve is jammed just leave it unless you fancy forcing it with a pair of footprints or small stilsons. The spindle may break inside the valve if you do but this normally happens when you try to open it again. Otherwise you can drain the tank in the loft.
 
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