I Am Soooo Confused

[dazzab]

Fitted a bath with a shower mixer on the deck.
Also fitted thermostatic shower valve on wall.

I took the feeds for the shower valve from the bath pipes like i have always done..

Problem is:
When running the hot water,it comes out for 2 mins hot then turns cold. Close tap and wait 1 min then turn back on and wholla hot water but then goes cold after 2 mins.

I am soo confused as i have spent many an hour (without pay)going through cures.

h/w is worked from a combi set at 1.5 bar
thermo shower is for low/high pressures.


any help or any questions much appreciated as they want me back asap to deal with it or no pay

 

[seco services]

the boiler is set to 1.5 bar on the heating so whats that got to do with the shower ?
is the boiler firing up when turned on ?
is the hot / cold round the right way ?

 

[LUNAT]

HI

is basin hot tap working correct ?
is bath hot tap working correct ?
if yes to both then the thermostatic mixer valve could be culprit

 

[dazzab]

yep sorry. but yes i mentioned 1.5 bar incase someone asks about pressures etc.


bath/basin taps run cold for a while then heat up and go cold then hot, so same prob. basin is 2 ft away from boiler.
kitchen taps getting hot water.

piping all correct.

im no corgiman but thought boiler might be the prob as i could not be airlock due to hot water coming out for a length of time .
im 10 yrs in the job but this is a first.

 

[doitall]

If you haven't got it sorted in 10 years you should pack up

How about back flow

 

[superdupergasman]

Try isolating the cold supply to the combi.

Turn on a hot tap, you should get nothing.... however you might
get water causing the cold hot water.

I have this very fault yesterday. Shower mixer faulty.

 

[dazzab]

nice 1 doitall i laughed my head off.

i undid all pipework and checked the out put and everything was the same...cold out of cold outouts okay.......hot out of hot outputs start hot then go cold then hot.

thank for all replies guys and keep em coming....all could be of help.

 

[doitall]

You need to do what SDG said and turn the mains to the boiler off, then try the hot taps for cold water.

 

[dazzab]

do ya mean isolate combi only while mains water is still on.???


blimey im back in training again.....lol

 

[Rob]

 

[jontheplum]

did you check hot water [boiler] was working correctly before you started working on the system

 

[dazzab]

nope never checked it but the customer says she has had it 7 years and serviced 2 months ago.
am back there in 2 days when i will try the isolation of combi.
im hoping its as easy as a diverter fault or any fault on combi as it has me stumped at the mo.
then she will have to get the inspector out again and ill get paid.
she cant blame me for that one eh (but i bet she'll try)

 

[dazzab]

spoke to a fitter today and he said that if the stopcock is opened right up that this can cause this problem so close it up a bit.
how true is this????

said that the pressure is overpowering the boiler??????????

 

[superdupergasman]

well if you only open the tap a little and its still doing the fault with a slow flow its not high flow causing this.

 

[manortim]

i had a customer with a combi and while the shower was being used, the water went hot/cold/hot/cold. looked a various issues, in the end i whacked a incoming mains pressuere reducing valve @3bar and stuck a non-return onto the hot supply pipe to the shower, cured it.

maybe your kit you've fitted is allowing backflow of cold?

basically what rob884 said.