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

 

[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??

 

[philtheflush]

wheres that pipe going to the other pipe that comes of the pipe where the pipe that runs under the pipe quite close to the pipe also right by the pipe near the cold mains PIPE

 

[PlumbBobBob]

you will have to back trace the pipework. the feed to the hot cylinder goes in the bottom of the cylinder maybe with drainoff on it, just follow it back up and you may be lucky and have a gate valve. although it may be up near the cold tank.

just had another look at the pics. to the right of the hot feed/vent is the cold feed to the cylinder it has a gate valve but without it's red handle. you can borrow the handle off the other larger gate valve to see if you can move it at all.

 

[rui7]

i see what ye mean, yeah if i remember correctly when i changed the element last year i used that valve to shut off supply to the tank. so if I shut that valve off, that will shut off the feed to the hot water taps. its starting to come together now!

 

[PlumbBobBob]

yes. it may be that the valve isn't open enough which would explain the slow running hot taps.

 

[Resolute]

That valve may have collapsed and need replacing too.

 

[rui7]

that cold feed valve is fully open. when i closed it fully the hot water was still running from the tap which is strange...

 

[PlumbBobBob]

it's broken and needs replacing

 

[rui7]

the cold tap flow fully stopped when i closed that valve fully but the hot tap flow continued to flow. The cylinder is very hot at the moment. Could it be that theres hot water in the cylinder and its continually expanding out from the top of the cylinder?