I have a gas combi boiler in my 2 bedroom flat which delivers scalding hot water to the taps in the kitchen and separate WC basin. However the water from the shower and taps in the two en-suite bathrooms is tepid. I have a British Gas contract, but they claim it is not their problem as the fault is in the taps. Grateful for any ideas as to how the hot water temperature can be different over such a short distance.
Hot water scalding from some taps, tepid from others
- Thread starter Aviator
- Start date
Sponsored Links
Shower:
Is it a thermostatic valve?
What if you turn the temperature control fully to the hot direction?
Basin:
Does it have a TMV (thermostatic mixing valve) underneath?
Both:
What is the flow like from the shower and the basin taps?
With someone observing the boiler behaviour, does it fire up when you turn on the basin tap?
Is it a thermostatic valve?
What if you turn the temperature control fully to the hot direction?
Basin:
Does it have a TMV (thermostatic mixing valve) underneath?
Both:
What is the flow like from the shower and the basin taps?
With someone observing the boiler behaviour, does it fire up when you turn on the basin tap?
Thanks for the reply.
Shower: It has a thermostatic mixer valve. Temperature is about the same at mid and fully hot.
Basin: Is a standard one tap mixer.
Both: Flow rates are reasonable and about the same throughout the flat. The burner cuts in 1-2 minutes after turning on the basin tap. (About the same for the kitchen tap which gives very hot water).
Hope this makes sense.
Shower: It has a thermostatic mixer valve. Temperature is about the same at mid and fully hot.
Basin: Is a standard one tap mixer.
Both: Flow rates are reasonable and about the same throughout the flat. The burner cuts in 1-2 minutes after turning on the basin tap. (About the same for the kitchen tap which gives very hot water).
Hope this makes sense.
which boiler
Sponsored Links
how old
1-2 minutes? Really? A combi should light up within a very small number of seconds, not minutes. Something's very wrong here.
It's a Powermax 155x, about 5 years old. Even though the burner did not cut in immediately, the water from the kitchen tap was hot. Is it possible that the boiler was already up to temperature because of central heating demand?
Effectively you have a tank of hot water which supplies the taps and if its temperature falls then the boiler heats it up.
There is a blending valve which aims to give a constant output temperature. Sometimes these do not work very well. It could well be involved in your problem.
Your thermostatic shower seems as if its faulty and thats quite common too.
Tony
There is a blending valve which aims to give a constant output temperature. Sometimes these do not work very well. It could well be involved in your problem.
Your thermostatic shower seems as if its faulty and thats quite common too.
Tony
OK. I'm not sure we're looking at the real symptoms yet.
Please would you conduct a test, which firstly involves turning off the central heating and not running any hot taps for a while, say 15 minutes, so that the pipes cool down.
Then open just the kitchen sink hot tap, about halfway (or less if it splashes too much), and feel the temperature while leaving open the tap for at least one minute.
Repeat this with the hot tap that is furthest from the boiler, then let us know whether the temperature stays the same, or fluctuates, or whatever, and how hot it feels, at each tap.
Please would you conduct a test, which firstly involves turning off the central heating and not running any hot taps for a while, say 15 minutes, so that the pipes cool down.
Then open just the kitchen sink hot tap, about halfway (or less if it splashes too much), and feel the temperature while leaving open the tap for at least one minute.
Repeat this with the hot tap that is furthest from the boiler, then let us know whether the temperature stays the same, or fluctuates, or whatever, and how hot it feels, at each tap.
Agile, I stand corrected - you're absolutely right - there's a 100 litre thermal store built in.
I was on completely the wrong track. So now I'm thinking that Aviator is not comparing apples with apples, i.e. is the shower being run when the thermal store is depleted?
I was on completely the wrong track. So now I'm thinking that Aviator is not comparing apples with apples, i.e. is the shower being run when the thermal store is depleted?
Have now been able to check the system with the boiler cold. The boiler fires up straight away when the kitchen tap is turned on, and the water runs hot pretty quickly. In the morning when the CH has been off all night, the water in the bathroom takes a long time before it runs semi hot/warm. I will try and get a time for this wait in the morning, plus a check if the boiler fires off straight away.
This morning, with the CH off all night, running the tap furthest from the boiler resulted in a time delay of 3 minutes before the burner cut in and the water started to heat. I will try the same thing with the closest tap in the kitchen tomorrow and see what happens. Any ideas please?
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
