Valiant ecotec plus 415

[Ducat2013]

Hi guys we have an valiant ecotec plus 415 boiler which has been fine for the last 5 years or more, only thing I have had to do was install a new ch pump a while back, no issues since.

Now it’s only firing up for heating, doing nothing for hot water, no error message nothing, the only way we can get hot water it changing the 2 port valve from auto to man (open) I have searched and don't believe the boiler has a diverter valve, so could it be the 2 port valve? But would this stop the boiler from even responding to the call for hot water??

 

[Harry Bloomfield]

But would this stop the boiler from even responding to the call for hot water??

It could. The valve has to signal to the boiler, that it has opened, before the boiler will fire to heat the water. The sequence is time-clock > cylinder stat > valve > boiler.

 

[Ducat2013]

It could. The valve has to signal to the boiler, that it has opened, before the boiler will fire to heat the water. The sequence is time-clock > cylinder stat > valve > boiler.

Ok in theory then if in man position and we called for water should the boiler not fire up without the heating, or does it not respond like that in the man position?

 

[Johntheo5]

Ok in theory then if in man position and we called for water should the boiler not fire up without the heating, or does it not respond like that in the man position?

No, the manual position is only designed to facilitate draining and filling the system so you don't want the boiler firing up with a empty system in case you havn't switched it off.
Check that the two port valve opens on auto, if the boiler doesn't fire up then more than likely a end switch problem.

 

[Mottie]

Hi guys we have an valiant ecotec plus 415 boiler which has been fine for the last 5 years or more, only thing I have had to do was install a new ch pump a while back, no issues since.

Now it’s only firing up for heating, doing nothing for hot water, no error message nothing, the only way we can get hot water it changing the 2 port valve from auto to man (open) I have searched and don't believe the boiler has a diverter valve, so could it be the 2 port valve? But would this stop the boiler from even responding to the call for hot water??

I had the same but in reverse - hot water working, heating not. Switching the power to the heating system on and off a few times would make it kick in. Fitting a new head on the 2 port valve on the heating side permanently cured the problem.

 

[Harry Bloomfield]

Ok in theory then if in man position and we called for water should the boiler not fire up without the heating, or does it not respond like that in the man position?

No, it only opens the valve.

With timer and cylinder thermostat, both set for demanding heat, the valve actuator should run to open position. If not, chances are - that the valve actuator has failed. Often that failure will be the actuator motor.

It's pointless just making assumptions, though - you need to be able to test things out, to determine exactly what has failed.

So far, you have only mentioned what boiler you have, a Vaillant. The Vaillant can have a variety of control systems attached to it, one of which is Vaillants own fancy control system. If it is a Vaillant system, skip straight to the test marked [1] below. Equally, you might have a more basic standard control system, like the one in the diagram below, which is a standard S-Plan diagram. Could you maybe identify the timer/clock + 2-port valve?

Assuming the latter type of control, and you have a suitable meter.....

Timer and cylinder stat, both set to call for heat.

The HW ON terminal should have 240v appearing on it.

Both terminals of the cylinder stat should have 240v on them.

[1]The orange wire going to the 2-port actuator, should have 240v on it.

If all above are true, then your 2-port actuator/head has failed. Some 2-port valves come as a unit - water valve + actuator, some you can buy just a replacement actuator. Identify the 2-port, and we can tell you which type it is?

The usual failure points on actuators, are the motor burning out, micro-switches failing, or simple wear and tear on the mechanism. You can buy replacement motors, or switches cheap enough, but the entire, new actuator/heads are not that expensive.

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[Harry Bloomfield]

I had the same but in reverse - hot water working, heating not. Switching the power to the heating system on and off a few times would make it kick in. Fitting a new head on the 2 port valve on the heating side permanently cured the problem.

Yep, almost certainly it will be a failure of the 2-port actuator. My system uses a 3-port, and I keep a spare, new actuator head to hand, ready to swap in just in case of a failure.

 

[Ducat2013]

Cheers for all the input guys, going to replace the head on the 2 port valve.

 

[Mottie]

Cheers for all the input guys, going to replace the head on the 2 port valve.

When you take it off, just make sure the spindle on the valve moves (they don’t move much though). Also, my new genuine Honeywell head came with an extra wire (white, I think) but the instructions tell you not to use it if you don’t already have it. I was advised to get a genuine head as they last longer than copies.

 

[Harry Bloomfield]

I was advised to get a genuine head as they last longer than copies.

Two heads are always better than one