vaillant ecotec plus 837 pressure rising

[123moose123]

Hi, I'm after some advice/guidance. I have a 3 year old vaillant ecotec plus 837 combi boiler and the system pressure keeps rising. I'm at my wits end as to what has gone wrong and how to fix it.
1, only hot water is in use. Heating has been off for all summer.
2, boiler has been drained and expansion tank pressure checked. 0.8 bar.
3, Internal filling loop is off. And doesn't seem to be letting by.
4, I did change one radiator in the spring, its an old cast iron big thing.
5, instructions say that expansion tank is only ok for up to 10lt, how big a system is 10lt?

Thanks for taking the time to help.

 

[The831Bunny]

99% of the time it is the filling taps passing. Disconnect the flexible hose at the heating isolation valve (lhs) and check there is no drips from the tube and/or valve.

 

[Bunnyman]

+1

 

[ScottishGasMan]

The systems not 10L the expansion vessell is. Depends on pipework/layout rad sizes etc, but a very general rule of thumb would be 10 -12 average sized radiators it could take, much more and your looking at adding an external vessel.

However this would only be seen to cause a problem when youve been using the heating.

What does the pressure rise to and how quick does it do it? Diconnect filling hose and see if it still rises as said.

 

[123moose123]

Thanks for the replies. Its an internal filling loop. It has 11 radiators, its a large 3 bed house. I will disconnect the loop and see what happens. Are the replacement internal loops easy to source?

 

[DeletedUser]

Thanks for the replies. Its an internal filling loop. It has 11 radiators, its a large 3 bed house. I will disconnect the loop and see what happens. Are the replacement internal loops easy to source?

Easy to source. You'll need cold inlet valve and the flow valve.
http://www.upperplumbers.co.uk/imag...lumbers_vaillant_ecotec_plus_filling_loop.jpg

 

[123moose123]

thanks it was the loop. capped both ends off and brought an external loop. thanks to all those who helped

 

[The831Bunny]

thanks it was the loop. capped both ends off and brought an external loop. thanks to all those who helped

Glad you got it sorted. Sometimes fitting an external loop is a lot cheaper if you have the space and can do it. Don't forget the 'thanks' button 😉