No hot water

[antocal]

Just recently my boiler won't heat the water in the bathroom taps or shower, the boiler fires up but the water is just slightly warmer than the cold tap. Hot water is fine at the kitchen sink. Today I played around with it a bit and noticed that the central heating flow pipe gets warm while any hot water tap is turned on (heating off). Looking at the manual I think this may be the divertor valve, but after speaking to valliant they think it may be the secondary heat exchanger.
They didn't give any explanation as to why either part would still allow hot water at the kitchen sink but no wher else.
Needless to say I am now confused and wonder if someone can advise. Following the manual I would be confident to replace either part but need to make the right call.

 

[Agile]

Telling us the boiler model would help !

If you cannot find the fault the usual advice would be to call a competent engineer.

Tony

 

[antocal]

Sorry,
Had the boiler details in the subject line but must have been too many characters.
Boiler is a valliant turbomax VUW242e.

 

[Agile]

It may well be the diverter valve.

You need to see if the boiler fires up for hot water when the heating is OFF !

Tony

 

[antocal]

Yes the boiler fires up when heating off and a tap is turned on.
But the kitchen sink is the only place I get hot water all other taps are cold.
The divertor valve makes sense but I would have thought the hot tap at the kitchen sink would be cold also.

 

[kinhell]

I had the very same problem this week and was told that the secondary heat exchanger would be blocked with sludge. It was either pay a few hundred quid and get the heat exchanger replaced or clean it.

I used Sentinel X800 sludge remover with success. Our boiler (Worcester Bosch 40cdi Combi boiler) had a problem with heating working fine but hot water being luke warm and going cold. I spoke to the guys at sentinel and they suggested X800 which is usually used with powerflushing machines. But I added it in just like an inhibitor and ran the bath quite a few times over 2 days. Its cleared the sludge that was probably in the plate heat exchanger and now the water is lovely and hot again. I have a magnaclean which picked up a lot of crap that the x800 stirred up. I've flushed it out and added the X100 inhibitor.

THe X800 was added in to the central heating system which in turn heats the water. So add it into the central heating loop at some point

By the way its ok to use X800 with aluminum plate heat exchangers for as long as you want according to Sentinel.

It worked for me and might work for you.

 

[Agile]

If the boiler fires up then the diverter valve is likely to be OK.

It sounds to me as if you have cold water entering the hot supply.

Test for that is to turn OFF the cold into boiler and see if anything comes out of the hot taps.

Thats often caused by faulty showers or joystick taps ( which should have been fitted with non return valves ).

Tony

 

[antocal]

Well, at this stage I'm just totally puzzled.
Have replaced the seconday heat exchanger and the divertor valve but still have same problem. Luckily the supplier will take the parts back.
I just can't understand why I get hot water at the kitchen sink but no where else. Two other sinks, a bath and shower and water at best is luke warm.
As I mentioned before CH flow pipe gets hot when the CH is off and any hot tap (excluding kitchen sink) is opened. I have closed the valves on the CH pipes but still same problem. Where is the hot water going!

 

[Agile]

I realish that you are Irish but are you unable to see and read ( and read ) my posting just before your last one?

Tony

 

[antocal]

Tony,
I have turned of the cold as you suggested and tried all the hot taps and the shower and nothing comes out.
Your advice makes the most sense especially as the divertor valve has been replaced is there anything else you can suggest.

Thanks
Anthony

 

[Agile]

OK so I think the diverter valve is OK.

That then leaves a largely blocked plate HE.

Whilst you get hot at the kitchen tap can you do another test?

Run a bathroom hot tap but only turn it on a bit so there is a slow flow rate and see if that gets warm.

Tony