Boiler Issue - No hot water to more than one tap at a time

Fud_Face · 7 Dec 2014

Hi All, guessing this forum area is busy at this time of year!

I have an issue with my Worcester Junior24i Combi Boiler producing hot water to more than one tap at a time.

Only one tap at a time can be hot and its increasingly worsened as the weather has got colder.

For example, if i'm running the hot tap in the kitchen (2nd closest to boiler) and you suddenly switch on the closest tap to the boiler the kitchen tap will then go cold.

I've asked the plumber that i usually go to and he is unsure.

So any help or advice in terms of troubleshooting the issue would be great!

Thanks

45yearsagasman · 7 Dec 2014

For starters, a Combi like yours will only supply one outlet at a time. That's all they are capable of. Incoming water temp will also affect the delivered temp. The colder the inlet water becomes the lower the final temp will be unless you reduce the flow slightly at the tap.

St0rmer66 · 7 Dec 2014

Welcome to 'owning a combi'. Guessing you're new to it?

MeldrewsMate · 7 Dec 2014

Does the closest tap also go cold?
Does the water from any single tap get as hot as the specifications suggest, e.g. 35 degree C rise at 12 litre per minute flow rate?

Is the kitchen tap (2nd from boiler) a mixer tap, if so set it to max hot water. Does it still go cold, or does the flowrate just drop ?

Early suggestions are a scaled-up DHW heat exchanger, restricting flow and also severely limiting heat transfer.

Fud_Face · 7 Dec 2014

I've had a combi boiler before in my previous flat and was able to have a shower no problem while taps were being used elsewhere so im quite curious as to why this one is different. The previous boiler was just a cheap biasi combi boiler. This time if im in the shower and someone uses a tap downstairs it goes freezing!

No the closest tap stays hot.

The taps downstairs are extremely hot. (when boiler wants to work perfectly) so yes i'd say it does reach the correct temperature specified.

The kitchen tap is not a mixer it is an individual hot/cold tap. I just went to try test what you said. All taps are currently lukewarm, It has been doing this now the weather is cold for some reason.

All the taps upstairs/including shower are warm but rarely very hot. The pressure of the water is strong.

MeldrewsMate said:
Does the closest tap also go cold?
Does the water from any single tap get as hot as the specifications suggest, e.g. 35 degree C rise at 12 litre per minute flow rate?

Is the kitchen tap (2nd from boiler) a mixer tap, if so set it to max hot water. Does it still go cold, or does the flowrate just drop ?

Early suggestions are a scaled-up DHW heat exchanger, restricting flow and also severely limiting heat transfer.

St0rmer66 · 7 Dec 2014

You may need to run the tap slower in winter.

We'd need to know the exact model. Your Biasi could have been 30kw and your current boiler 24kw for instance. You might have had a lower flow rate at the old place and a higher one at the new place. There are many factors to consider before jumping to conclusions about it being faulty!

MeldrewsMate · 7 Dec 2014

Some boilers have a diaphragm operated diverter valve, when this starts to fail it restricts heat to the output, and sends the rest into the heating system......that's why we want to know the make and model of the one you're complaining about.

Fud_Face · 7 Dec 2014

MeldrewsMate said:
Some boilers have a diaphragm operated diverter valve, when this starts to fail it restricts heat to the output, and sends the rest into the heating system......that's why we want to know the make and model of the one you're complaining about.

I mentioed it in the first post unless im missing part of the model number?

The model is Worcester Junior24i Combi

JohnD · 7 Dec 2014

dmcg85 said:
This time if im in the shower and someone uses a tap downstairs it goes freezing!

then it might be a result of your shower, or the pipes to it. I presume it is a mixer without thermostatic control.

Does the bath or basin taps do the same thing?

Dan Robinson · 7 Dec 2014

But what was your old boiler. Currently you have a boiler that lurks in the boiler equivalent of the "Chicken Cottage " end of the gastronomic world.

One tap really is your limit. And when there is snow on the ground, you will be grateful for that.

St0rmer66 · 7 Dec 2014

dmcg85 said:
MeldrewsMate said:

Some boilers have a diaphragm operated diverter valve, when this starts to fail it restricts heat to the output, and sends the rest into the heating system......that's why we want to know the make and model of the one you're complaining about.

Click to expand...

I mentioed it in the first post unless im missing part of the model number?

The model is Worcester Junior24i Combi

Missed that! 24kw is the smallest size combi you can buy, so it's not for fun to give a good flow rate. As soon as the incoming water temperature drops in winter you need to run the taps slower.

It doesn't have a diaphragm btw, just a flow switch.

Sounds like you have a standard mixer shower instead of a nice thermostatic one which would help stop it going cold!

Fud_Face · 7 Dec 2014

JohnD said:
dmcg85 said:

This time if im in the shower and someone uses a tap downstairs it goes freezing!

Click to expand...

then it might be a result of your shower, or the pipes to it. I presume it is a mixer without thermostatic control.

Does the bath or basin taps do the same thing?

Yes the bath and basin taps do the same, the shower is the last in line in terms of the plumbing so is always effected. It is also a thermostatic mixer.

The previous boiler was a Biasi Riva Advance HE

Dan Robinson · 7 Dec 2014

I still think we have a situation of managing expectations

14l/min at 35 degrees delta and now you have 9. Both boilers are warnk.

Fud_Face · 7 Dec 2014

Dan_Robinson said:
I still think we have a situation of managing expectations

14l/min at 35 degrees delta and now you have 9. Both boilers are warnk.

I wouldn't say that was the case, yes they are not great boilers but that doesn't explain why previously the boiler worked without issues before.

St0rmer66 · 7 Dec 2014

dmcg85 said:
Dan_Robinson said:

I still think we have a situation of managing expectations

14l/min at 35 degrees delta and now you have 9. Both boilers are warnk.

Click to expand...

I wouldn't say that was the case, yes they are not great boilers but that doesn't explain why previously the boiler worked without issues before.

How many times do we need to say it?

. The cold water coming into the house drops by 10 degrees or more in winter. Therefore so does your hot water if you run it at the same flow rate. Slower water, hotter water. More powerful boiler means faster flow at the same temperature. You have a minimum sized combi and by the sounds of it a fast flow rate.

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Boiler Issue - No hot water to more than one tap at a time

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