Valliant EcoTech min output

[Gary27]

I have a Valliant 418 with a minimum output of 5kw, is there a way of reduceing this further. Although 95% of the time it behaves now and then 5kw is still to high for my installation and it can cycle.

Just though I would ask, tweeked other setting and pump speed to get it to work as best as I can.

Gary

 

[Dan Robinson]

The minimum output is governed by the burner and gas valve's capacity to maintain a stable flame.

5 is as low as yours can go.

 

[Gary27]

The minimum output is governed by the burner and gas valve's capacity to maintain a stable flame.

5 is as low as yours can go.

Thanks, just though I would check, read on another make you could reduce minimum fan speed.

Gary

 

[Dan Robinson]

There are all sorts of things you can do to all sorts of boilers, but they are issued a certain way for a reason.

Yours with 5kW is what Vaillant are happy to say will provide a stable SAFE burn in all conditions likely to be met across the UK over a year.

the cost benefit of trying to minimise the cycling is not worth it.

*edit* - keyboard shenanigans...

 

[ALEC1]

you mean not worth it Dan surely...

 

[Dan Robinson]

Indeed....

 

[scoobydo123]

Gary when does yours cycle? Could you check to see what happens when your cylinder thermostat calls for heat, your boiler may well cycle once the cylinder gets close to recovered. What happens when it fires up after the cycle? Do you hear it start at a very high fan speed and then probably only stay on for 10 seconds (please no CH demand during this process) and then cycle like this until it finally recovers the cylinder.

 

[Gary27]

Gary when does yours cycle? Could you check to see what happens when your cylinder thermostat calls for heat, your boiler may well cycle once the cylinder gets close to recovered. What happens when it fires up after the cycle? Do you hear it start at a very high fan speed and then probably only stay on for 10 seconds (please no CH demand during this process) and then cycle like this until it finally recovers the cylinder.

After various changes to setting including weather comp curve I think it just comes down to fact the house cannot dissipate 5kw for the entire cycle. Manages most of the time but sometimes shuts down, waits then restarts. It's just that sometimes the wait is not long enough and it takes a couple of cycles before the rads have cooled.
Gary

 

[ALEC1]

you need to google vaillant cycling problem blog...

 

[Gary27]

you need to google vaillant cycling problem blog...

Done that, thats how I have got it to work 95% of the time OK, it was just I came across someone that managed to down rate their boiler more than just with the normal setting, but it was not a Valliant.

 

[Dan Robinson]

What boiler was it? And did the person doing it have the understanding and the equipment to to it safely and correctly?

 

[Agile]

Gary, it seems the only problem is that the boiler needs to cycle in order to maintain the required flow temperature.

Thats the result of having a boiler which has a higher heat output than you need.

I dont see anything that you can do about it and its not such a problem anyway.

Much more of a problem when a 35 kW boiler has been fitted!

Tony

 

[Gary27]

Gary, it seems the only problem is that the boiler needs to cycle in order to maintain the required flow temperature.

Thats the result of having a boiler which has a higher heat output than you need.

I dont see anything that you can do about it and its not such a problem anyway.

Much more of a problem when a 35 kW boiler has been fitted!

Tony

I think you are right, it was just a question can a Valliant be slightly down rated within the settings other than the normal d0 setting. Its not that big an issue now I have the pump speed correct and the curve set actually lower as this gives a longer wait time. Also I make use of all the rads in the house and not turn some off. It is derated down to 12kw and I have set the minimum ch temp to 48c and the max to 60c.
Gary

 

[Agile]

Why not set d0 down to 10 kW?

You can always increase when the weather is colder!

 

[hazetimesfive]

whats wrong with it cycling?