valiant combi problems

[dazza1112]

turbo max plus valiant boiler ch fine. hot water downstairs fine upstairs only luke warm

 

[pierrot]

smells like a flow rate problem.
try running the tap a little slower to start with.

 

[chrishutt]

Cold water feeding back into hot pipework via shower valve with missing or faulty check valve? Check temp changes in hot pipework to shower.

 

[weareleeds]

Check diverter valve by running hot tap when rads cold to see if 22mm pipework under blr gets hot.You may have one of the early valves. If you can see the valve check the size of holes drill through the brass body if they are about the size of a pencil it is the newer valve, if it about the size of a biro insert then you have a suspect valve & needs changing

 

[HarrogateGas]

Id go with chrs on this one........faulty mixer tap/shower. Diffuclt to prove although a cheap way is to fit non return valves on the hot supply to any mixer taps or showers.

I had a problem like this only last week..only the bathrrom taps were running luck warm, every other hot tap in the propert was fine. it turned out to be a the mixer shower passing. the customer wasnt intrested in a new shower but a non return valve hid the problem.

 

[dazza1112]

I have 3 "taps" upstairs, the bath the sink and the shower they are all luke warm, so it cant be a faullty mixer

 

[chrishutt]

When you run the shower will the shower only get luke warm even if you put the temperature setting of the shower on max?

 

[dazza1112]

yes its the same with all the taps upstairs which are all mixers

 

[chrishutt]

When you are running hot water from any of the outlets that are lukewarm, what temp. is the hot water outlet pipe from the boiler (the second from left)?

If it is also lukewarm, what happens to the temp. if you reduce the flow by turning down the tap so that flow is only about 5 litres/minute?

 

[Agile]

Id go with chrs on this one........faulty mixer tap/shower. Diffuclt to prove although a cheap way is to fit non return valves on the hot supply to any mixer taps or showers.
quote]

Its actually quite easy to prove. Turn off the cold supply inlet to the combi boiler and nothing should come out of any hot outlet!

Problem can arise with some thermostatic showers because they always mix about 10% of cold water to prevent scalding.

Seals in some mixer taps can fail and allow cold to pass into the hot. However if they had been fitted correctly they would have had non return valves.

Tony

 

[chrishutt]

Its actually quite easy to prove. Turn off the cold supply inlet to the combi boiler and nothing should come out of any hot outlet!

Of course, why didn't I think of that?

 

[ChrisR]

Of course, why didn't I think of that?

Haven't read enough web forums!

 

[HarrogateGas]

Id go with chrs on this one........faulty mixer tap/shower. Diffuclt to prove although a cheap way is to fit non return valves on the hot supply to any mixer taps or showers.
quote]

Its actually quite easy to prove. Turn off the cold supply inlet to the combi boiler and nothing should come out of any hot outlet!

Problem can arise with some thermostatic showers because they always mix about 10% of cold water to prevent scalding.

Seals in some mixer taps can fail and allow cold to pass into the hot. However if they had been fitted correctly they would have had non return valves.

Tony

Depends if its only passing under pressure though.

 

[dazza1112]

The quicker the water flow, the cooler the water.
Like wise with the pipe coming from the boiler. it is very hot when the taps are only open a little, but cools off as the taps are open further

 

[chrishutt]

Well that's what is supposed to happen. The boiler (depending on model - you don't give number) should deliver around 9 litres per minute at a temperature 35C higher than the incoming cold water temperature. Can you measure the flow rate and temps on yours to see if it's about right?