Mystery Worcester Bosch Combi Status Code 265.

[Peter155]

Can anyone please explain why my 12 month old WB Greenstar 28CDi Compact ErP Combi with fascia mounted Comfort ll room stat continually stalls with a 265 Status Code "Stand-by mode forced due to energy transfer limit", causing it to take twice as long to reach the set room temperature than it should. This has been a continual problem since installation in November 2021. HW has no problem and works fine.

If you can then you will be better than the installer, service engineer, and 3 WB engineers who say they have never seen this status before, and seem to be unable to fix it.

Thanks in advance.

 

[John.g]

I think I asked before but what is the flow/return dT typically before it reaches that 4C dT and what was/is it when running the boiler at say 10kw or thereabouts?

Have those Drayton TRVs got a setting index that' you can adjust for balancing?

 

[Peter155]

I think I asked before but what is the flow/return dT typically before it reaches that 4C dT and what was/is it when running the boiler at say 10kw or thereabouts?

Have those Drayton TRVs got a setting index that' you can adjust for balancing?

The power setting doesn't seem to make much difference to the flow and return temperatures, just the time it takes for them to collide. They start off very similar, in the 20s or 30s, then the flow increases slowly or quicker, depending on the power and pump settings, and the return comes along behind it, gradually gaining on it, generally not catching it until the flow is in the 40s. The only time the flow gets much hotter, I think 61 is the highest I remember seeing (SP was 60), is when I push the room stat up by at least 2 degrees and then it runs solidly for a while until the gap narrows or up pops one of the others codes I mentioned earlier, or it goes straight to a 265 shutdown.

Sorry, I don't know what you mean by a setting index on the TRVs. It seems to have a movable pin with which you can adjust to limit the range, is that it? but I have never used that feature.

 

[John.g]

Have a look at this, the default settings are 4 for the pin (max temperature setting) and 6 for the flow settings (max flow setting) so shouldn't have any effect but as suggested maybe remove the heads.
Normally, once the system is up to temperature, for any given flow rate and heat demand and as long as the boiler output matches the heating demand then the dT should not change until the roomstat is satisfied?, if the dT starts reducing then the flow rate would have to increase which seems improbable. If the heating demand is less than the boiler minimum output then the return temperature will start increasing but so too will the flow temperature at the same flowrate.

Also, running with a flow temp of 60c and a dT of 20C results in the rads only emitting 51.5% of their rated output, so assuming your total rad output at 15kw then output at 60C is 7.7kw, close to the boiler minimum output.

https://www.draytoncontrols.co.uk/news/unlocking-secrets-trv4-0

 

[Peter155]

Have a look at this, the default settings are 4 for the pin (max temperature setting) and 6 for the flow settings (max flow setting) so shouldn't have any effect but as suggested maybe remove the heads.
Normally, once the system is up to temperature, for any given flow rate and heat demand and as long as the boiler output matches the heating demand then the dT should not change until the roomstat is satisfied?, if the dT starts reducing then the flow rate would have to increase which seems improbable. If the heating demand is less than the boiler minimum output then the return temperature will start increasing but so too will the flow temperature at the same flowrate.

Also, running with a flow temp of 60c and a dT of 20C results in the rads only emitting 51.5% of their rated output, so assuming your total rad output at 15kw then output at 60C is 7.7kw, close to the boiler minimum output.

https://www.draytoncontrols.co.uk/news/unlocking-secrets-trv4-0

Hi John

Thanks for that. I certainly hadn't realised that the TRVs could be set up differently so that's food for thought. I am also teaching myelf about Delta T which I had never heard of.

My plan is to get Christmas out of the way and take on board all the advice you and others have kindly given me, and try and get my head around exactly what is happening with my system and go through the various recommended set up procedures and see if anything works. If nothing improves then I shall be back on the phone bending the ear of my installer and the WB technical people. I'll let you know how I get on.

Many thanks again for all your advice, and I hope you and yours have a great Christmas 🎄☃️🎅

Cheers, Peter

 

[John.g]

Many happy returns to you and yours Peter.

Just a final thought re the changing flow/return dT of 20C/4C, you would no doubt have spotted it but if the burner cut out then the return temp will continue to rise slowly but the flow temp should fall and obviously the dT will reduce to 4C or so during the 10 min recycle time.

If you do get the experts back, ensure that they also /renew that internal bypass.

 

[Peter155]

Many happy returns to you and yours Peter.

Just a final thought re the changing flow/return dT of 20C/4C, you would no doubt have spotted it but if the burner cut out then the return temp will continue to rise slowly but the flow temp should fall and obviously the dT will reduce to 4C or so during the 10 min recycle time.

If you do get the experts back, ensure that they also /renew that internal bypass.

Thanks John, will do 👍