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

[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

 

[tamz]

Depends if you cqan work a spanner.
The fitting coming off the top of the cylinder is the 1st place to check.

 

[Guest123]

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!

 

[rui7]

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?

 

[rui7]

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.

 

[rui7]

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.

 

[PlumbBobBob]

the cold is probably mains pressure so wouldn't show up as much

 

[rui7]

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.

 

[PlumbBobBob]

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.

 

[Guest123]

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.

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.

 

[rui7]

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.

 

[rui7]

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?

 

[Resolute]

Could be a collapsed gate valve?

 

[Guest123]

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.

 

[zzzjim]

In the quiet , any gurgling noises ? , may be an airlock and some sediment .
Curing this could send sediment the wrong way !

 

[rui7]

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.

 

[rui7]

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.

 

[rui7]

no gurgling noises at all.

 

[PlumbBobBob]

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.

 

[Resolute]

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.

 

[rui7]

ok i get ye, i will have to try this tomorrow. I will post back what happen. thanks for all the helps guys!

 

[rui7]

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?

 

[PlumbBobBob]

yes that's right

 

[rui7]

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?

 

[tamz]

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.

 

[Guest123]

This is the way I do a pipe flush, but please you really must know what you're doing and it's as a last resort:
Switch off the cold mains supply, drain your storage tank.
Switch of the gate valve at the tank supplying your cylinder.
Thoroughly clean out the tank.
Cut a washing machine tee into the 15mm main supplying the tank.
Cut a 22mm tee into the 22mm cold feed supplying the cylinder, reduce this to 15mm with a reducer and connect a straight washing machine valve.
Connect one to the other with a washing machine hose.
Open both valves for about 30 seconds, leave running and then open hot tap at lowest point, usually at kitchen.
All the dirt, debris, scale etc should flush out and come out at the tap. Repeat this until clear.
Switch off washing machine valves in attic.
Clean the tap aerator when finished.
Refill system, washing machine valves for about 20 seconds to flush out air and then close.
Disconnect and cap off washing machine valves in attic.

Done this procedure many times and it works really well, but please don't attempt it unless you know what you're doing.

As Tamz says you can disconnect the cylinder coupling and check for a loaclised blockage there, but loosen it with care or you may burst the cylinder.

Personally, I'd "bite the bullet" and get a plumber in from the forum. Money well spent in the long run.

 

[rui7]

Hi,

thanks for all the info. Yeah I wouldn't be capable of doing that flush out procedure.

I did connect the washing machine cold to the hot under the sink and opened up the hot taps. The flow was fine but not has fast as the normal cold taps but it was a big increase as what the hot water flow would be. There was no sediment or debris and no spluttering. Then I switched it back and the hot water flow was still the same slow rate.

So the next thing will be to try tamaz's suggesting. So is it only the hot taps that are fed by this section coming off the top of the cylinder? The shower must be fed by a separate feed as that hot flow is fine.

Yeah, a plumber may be a good call.

 

[PlumbBobBob]

hi can you put a picture of your hot tank showing the connections to it, we may see something that needs changing to get your hot taps working

 

[rui7]

heres some pics.

 

[philtheflush]

theres more pipes there than the edinburgh military tatoo

 

[rui7]

haha I know. looks like its an indirect heating system if im right. Wheres the pipe feeding the hot water for the shower+

 

[PlumbBobBob]

that would be the pipe that comes off the pipe that is at the top of the cylinder and the cold feed is from the other pipe by the side of the hot feed/vent pipe. in one of the pictures you can see where they go through the wall to the shower.

 

[rui7]

theres a pipe on the lower middle right side of the cylinder which I thought was for the showers. I thought the top ones which are going through the wall are the tap feeds, where are the tap feeds then?

 

[PlumbBobBob]

the tap feeds will be teed into the hot feed under the floor. the pipe off the top of the cylinder goes down towards the floor and up towards the cold tank in the loft and acts as the vent for the system, it goes up and over the cold tank.

 

[rui7]

ah ok, so the main pipe coming off the top of the cylinder tee's at the back, the section going upwards is the vent to the loft cold tank and the section going down feeds the hot taps.

I thought the far left red wheel was for the hot water shut off but that seems to be the heating systems pipes. The other red wheel is the cold shut off so where is the hot shut off??