Vaillant turbomax Luke warm on Dhw

[proelitegas]

Hi got a call from customer only getting Luke warm water on
Dhw. Any ideas I'm suspecting temp thermistor or maybe plate heat
X Changer? Customer not sure of what fault codes are displyed. Also complaining of pressure rising when hot tap turned on g pressure gauge on boiler goes up

 

[CES]

If pressure is rising when hot water turned on then you have a pinhole in the dhw heat exchanger. Mains water tracking back into the ch circuit when dv moves into dhw position. Lukewarm dhw is usually either plate heat exchanger or DV, in this case it sounds like a new heat exchanger.

 

[Jonwells]

With turbomax, the only problems, I have had is diverter or plate.
Turn on hot water and see if boiler is modulating, ( on off), check to see if water is being dumped into heating cucuit, if not see if hot water is being passed into plate from primary circuit, if it's not it's plate, if primary circuit is Luke warm and boiler is on and more off, it's ntc or thermostat. Jon.

 

[diamondgas]

:iagree: as above ... check out the expansion vessel also regardrs the system pressure rising

 

[leedsgasservice]

Had a similar fault with the ecomax,only getting luke warm water as the burner stayed on low flame. Ended up tracing fault to a broken wire on the dhw flow switch. Obviously if the boiler is over pressurising could be dhw heat exchanger.Good luck.

 

[proelitegas]

Thanks having a look at it Tom will you all soon as ive sorted it

 

[Billy Bob Bob]

i would be careful of what the custard says,for example we know the pressure will increase with the boiler running but of course not to 3 bar,i had one this week who had low pressure on a performa it must be broke the burner on lights on when i run the hot tap *sigh*(expression nicked from diamond gas)anyway take the resistance of your dhw thermistor and compare it to mi,s you will need to measure this with a COLD boiler,if this proves to be in spec is the ch flow pipe getting very hot in dhw mode?if so look at the divertor or plate heat

 

[proelitegas]

Thanx gas man will get the multimeter out Tom...