Mend > Home Heating Systems

Mend Vaillant Combi Boiler Home Heating Pressure

how can i fix my valliant combi boiler?

i had the boiler serviced last month and a new part that helps with the pressure was fitted but still the pressure drops every time the boiler isnt on (it drops to 0) and i have to add more water from the twist button under the boiler to get to 1.5 on the pressure. Any ideas

sue thrupp
January 2007

Vaillant Heating, Home Heating Systems Combi Boiler Home Heating Pressure

thank you kevin for that response will get it sorted asap

sue thrupp
January 2007

Hello Sue,
To start I am not a plumber, however I do all my own maintenance and and installations. This sounds like you have a leak in the Direct Heating Water loop. In the combi boiler the DHW either heats the radiators or heats the incoming cold water indirtectly via a heat exchanger. If there is no obvious water leak in your heating system then the possibility is that the heat exchanger is leaking internaly and would need to be replaced. This would require someone who had the correct equipment to pressure test the heat exchanger to check for leaks.
If you had this problem prior to the maintenance being done, it is something that a good service "engineer" should have done before replacing parts in the hope of repairing the problem.

I hope this was of some help.

Kevin Wilkinson
January 2007