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Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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My vaillant ecotec boiler works OK except when short cycling

Customer Question

My vaillant ecotec boiler works OK except when short cycling between 40 degrees and say 70 degrees. What can I do please?
Submitted: 2 years ago.
Category: Appliance
Expert:  Plumberpro replied 2 years ago.



Hi , what happens when between those temperatures?

JACUSTOMER-v3g9hnm1- :

The radiators upstairs are warm but the downstairs radiators are cold.

JACUSTOMER-v3g9hnm1- :

The system has been drained, topped up and bled of air.

JACUSTOMER-v3g9hnm1- :

When not short cycling all seems well.

JACUSTOMER-v3g9hnm1- :

It is as if the boiler is OK but being instructed by a programme other than the usual thermostat / pump demand command.

JACUSTOMER-v3g9hnm1- :

Can I override this by using the plus and minus buttons somehow? I have not touched these buttons yet.


Hi , if you had been patient I could have helped you with this . we are not robots on the site 24 hrs a day. If you still need help then you will have to re rate me


Firstly Open all the radiator valves donstairs( both sides) fully and see if any there is a change.

JACUSTOMER-v3g9hnm1- :

The radiator valves are open.

JACUSTOMER-v3g9hnm1- :

I am new to this website so was disappointed that I was asked questions without a hint of a solution to my problem. When you have been cold for many days you don't feel charitable. I have rerated as requested to move things on. I will rerate later as warranted.

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Expert:  Plumberpro replied 2 years ago.
Ok , I understand that . did you open the rad valves fully both sides down stairs?
Expert:  Plumberpro replied 2 years ago.
Hi , I am pretty sure that it may be ac flow issue due either to weak pump or a blockage in the heating system ( sludge or air) . I have to go out for an hour . do you mind if we continue in an hour or so ? Thanks
Customer: replied 2 years ago.

The system has been flushed with an anti sludge liquid by a plumber and the pump cleaned.

The plumber did say he thought that the heat exchanger may need replacing but this seemed more in desperation than logical analysis.

I don't think the plumber was expert in setting up the Vaillant ecotech 415 boiler because after two weeks of flushing and tinkering no progress was made and he left me with a system that provided little heat to the radiators although plenty of hot water.

The plumber is semi retired and no longer Gas Safe registered. I wonder if he has kept up to date with the technology.

I managed to get some radiator heat upstairs by studying responses to internet searches and finally managing to restart the boiler and avoid persistent F23 codes by gradually increasing the radiator max temperature over an hour to just over 70 degrees. This gave me some heat in the upstairs radiators but not downstairs.

I feel disloyal in saying the above because I have used the plumber for nearly 30 years but the boiler is only 7 years old and I need independent help.

Expert:  Plumberpro replied 2 years ago.
Ok , has any pipework been changed?
Expert:  Plumberpro replied 2 years ago.
I really feel , there is an airlock somewhere. Look for air release valve on pipework near the hot water tank and in the loft. .
Also change the temperature thermistors/ stats on the boiler .

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