Hot out of cold tap on unvented

[justlead1]

Hi A pal has had a plumber round to sort a fault on a new property (one year old) plumbing system. Unvented heated via gas boiler and solar. When the cold tap are run hot water flows. (non stop) It may be a balanced system (info was over phone from a layman) Has anybody come across this fault with this type of system.

 

[Gray0689]

Is hot coming out of both hot and cold taps
If not the pipework might be cocked up

 

[ferret]

Could also be cheapo mixer valve on shower or mixer tap letting by , turn off hot supply and try taps again if running cold look at the mixers.

 

[justlead1]

Hi Guys Is happens with no other appliances on (pipe are as they should be ) its been working fine up to three weeks ago. I wondered my self if a a temp blender is fitted down stream of cylinder. But i have had not experience with this sort of set up (if it exists)

 

[BLOD]

What was the problem the pals plumber was sorting out ?

 

[plumbman]

hi i have had the exact problem on one of my installations same set up solar,unvented problem still unsolved leeds area

 

[Toddyplumb]

Could it be the cold feed is taken off after the non return valve and water is coming from cylinder instead of cold main ?

 

[moony]

Could it be the cold feed is taken off after the non return valve and water is coming from cylinder instead of cold main ?

good thinking batman

 

[ferret]

Could it be the cold feed is taken off after the non return valve and water is coming from cylinder instead of cold main ?

Not if it is only a recent problem , it must be something mechanical failed like a mixer/blender

 

[justlead1]

Hi Gentlemen thanks for your input. How it come about, just a social call to a pal. He remembered my plumbing carrear. Told me of the problem, and the body language of plumber sent to investigate, suggested he was lost. He went of to order parts. Never to be seen again. What prompted him to call out the plumber was, when using the toilet, he lent back to celebrate the function, bare back touching cistern. The reaction that followed caused him to rick his neck. I will keep you informed as the job unfolds.

 

[Gray0689]

Is it hot water in wc and taps

 

[Toddyplumb]

Not if it is only a recent problem , it must be something mechanical failed like a mixer/blender
I always thought that the the TMVs failed to safety ?
Interesting if it does fail safe and then puts hot out of the cold taps through the cold connection ? Oh ****
If this proves to be the case , for a solar with TMV the balanced cold comes off before NRV BUT the cold to TMV has to come off after the NRV to stop reverse flow . Im gonna av a look at MIs
Check them all , NRV may have jammed , they are only plastic inside
Just looked at INTA Solar TMV there schematic shows NRV on cold feed to TMV . Should be easy to check

 

[justlead1]

Hi Thanks again. I may well get more involved with a visit.(if i am not careful) Trying to avoid adopting the system for life. I am sure you all understand this reference.

 

[keeny7293]

deffinatly check for a non return valve!