Hi I need help,
I have a vaillant 828/2e turbomax boiler and I'm having problems with getting constant hot water. The heating works fine no issues there. When any tape is open to get hot water the boiler will go through the same sequence of hat then warn water. I've looked at the program sequence and it keeps going through the following status modes. S.10, S.13, S.14 then repeat the sequence.
Does any one have any idea what could be wrong.
I've changed the diverter valve and aqua sensor. could it be the main c/board.

Cheers

RC, October 2008

take the front cover off and then check the hot water, if it is ok and when you put the cover on it goes back to normal(ie cold water) it is the seal on the combustion chamber(gas burner chamber) it is leaking C02 and the air to C02 ratio goes to Pot, very easy repair 5 nuts on the cirlinderacle cahmber and change seal (cost £15 + Vat)( i have had the same problem and change the seal it is working fine know)

MK, February 2009

THanks tojo it was the secondary heat exchanger

rc, November 2008

Have the flue switch checked by a competent person - it senses the fan is running.
On DHW demand the boiler ignites with a high flame, which causes a pulse of pressure in the combustion chamber. This can cause misoperation of the flue switch, leading the boiler to drop out of the ignition sequence - then it tries again . . .and again.

On central heating the flame is modulated to a low start up setting and there is less of a pulse. The boiler will frequently ignite without problems.

Anengineer, November 2008

possibly scaled up secondary heat exchanger, if boiler temp keeps shooting up then burner modulating down again or going off possibly because heat can't transfer to secondary

tojo, October 2008