Evohome continually bringing boiler on for one minute then off for 10 minutes

[colin_]

If another boiler without the soft start function comes on, what temperature does the output from the boiler get to (from 30 degrees) in 1 minute and in 2 minutes?

Thanks
Colin

 

[ShaunCorbs]

You get the full rated output within 20 seconds ish

 

[John.g]

It is the boiler that that does the soft start and takes ages to heat its output water to 70 degrees. The hot water will go from ~45 degrees to 60 degrees in around 20-25 minutes (dependent upon what else it is heating at that time)

Thanks
Colin

You will have to try and get that soft start sorted out, ironically, there are numerous posts around re gas boilers firing up at 70/80% of output for up to a minute before modulation and actually cutting out on high flow temperature, you can't win.

 

[colin_]

You get the full rated output within 20 seconds ish

So the boiler I have will probably not play well with the Evohome if it expects the full heat well within the minute (as it needs up to 10 minutes!)

Thanks
Colin

 

[ShaunCorbs]

So the boiler I have will probably not play well with the Evohome if it expects the full heat well within the minute (as it needs up to 10 minutes!)

Thanks
Colin

No boiler will do that you should be able to change the perimeters of evo to adjust this

 

[John.g]

That definitely makes sense.

 

[colin_]

No boiler will do that you should be able to change the perimeters of evo to adjust this

Hi

I adjusted the evo to keep on for 2 minutes but all that happens is it gets to ~40 degrees before tunring it off (nowhere near the 70 degrees set on the boiler).

Near the end of the 2 minutes you can hear the tone of the boiler change as it starts to modulate up, ust in time for the Evohome to tell it to stop.

Not sure I want to go longer than 2 minutes as gas usage will go up rather than the heat.

There appaears to be a parameter 5-A3 "Minimum boiler output (heating and DHW)" whose default is 10% (and max is 50%). I will be asking the installers (who did the boiler and Evohome) whether this needs to be set higher (perphaps 20-25% or higher?) so the boiler does not modulate so low at the start (especially as the Evohome will be in control)

Thanks
Colin

 

[ShaunCorbs]

Need to go longer else you will knacker your boiler as there designed to run longer

 

[colin_]

Need to go longer else you will knacker your boiler as there designed to run longer

The default of the Evohome is 1 minute on time (max is 5 minutes) when it is in the cycling mode (6 timers per hour).

I rang Worcester technical several days agao and he said the boiler would be happy doing it!

The boiler has the Worcester 12 year warranty so hopefully all should be well on that score.

When set for 2 minutes it only gets to 46 degrees before it turns it off again.

I have set it for 3 minutes now and when it came on it was still only 46.3 after 3 minutes - I am still (unfortunately) monitoring it.

I am waiting to see what the installers think after contacting Worcester technical about what the 5-A3 "Minimum boiler output (heating and DHW)" does and the ramifications of increasing it.

Thanks
Colin

 

[John.g]

The majority of boilers only modulate 5 or 6:1 but yours is 10:1 so maybe to replicate these boilers increase the min output to 25/30% (5-A3) and see how it goes, can't do any harm. and can always revert.