@jamespa The flow temps scale is on the image James, but now I look at the values rather than the difference between them they are very low 24C flow with a Delta T of about 4C.

I cant help but think i must have a setting wrong somewhere.

Without jury rigging something I wone be able to run the destratification pump as it loops through my PV diverter.

Posted by: @bontwoody

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@jamespa The flow temps scale is on the image James, but now I look at the values rather than the difference between them they are very low 24C flow with a Delta T of about 4C.

I cant help but think i must have a setting wrong somewhere.

I can't see anything obviously wrong in your settings that would cause the behaviour you are seeing.

Can you check FSV 105*

Can you increase #3021 to 55C?

What temp have you set on the controller as the set point (desired temp) for the DHW? Also, what mode does the controller show (Economic, Standard, Power, Forced?). Just stick with Standard whilst you are trying to get things working.

How is your immersion wired? Is it wired directly into the mains or is it wired into the Samsung controller?

#3031 controls this (Samsung refer to it as Booster heater). If it's wired directly into the mains on a manual on/off switch, then you can set to NOT USE as the Samsung controller cannot see it anyway.

If you want to use the booster heater (immersion) to top up the DHW tank temp after a heat pump run with the indirect coil, then #3032 needs to be less than #3025 (both currently 95mins)

For example, if you wanted a maximum 90min DHW cycle, with 60mins by the ASHP and then the immersion taking over for the final 30mins, you'd set #3025 to 90mins (total time) and #3032 (booster delay) to 60mins.

@old_scientist Hi.

Ive done as you suggest 3021 -55C etc.

I know I set the heating mode to Economic but now cant find it again to change it back to standard!

What is a little confusing is that the DHW temp is dimmed at 45C and I cant alter it.

@old_scientist.. Ah found the heating mode in the schedule 🙂 Now standard

Posted by: @bontwoody

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@old_scientist Hi.

Ive done as you suggest 3021 -55C etc.

I know I set the heating mode to Economic but now cant find it again to change it back to standard!

What is a little confusing is that the DHW temp is dimmed at 45C and I cant alter it.

 

It's dimmed like that because it's currently turned off.

It will either turn on/off by schedule (daily) or by manually turning on/off on the front panel using the power switch, illuminated on left hand side. You can only adjust the set temperature (45.0C as shown) when the DHW is turned on. When it's off (greyed out as in your pic), you cannot adjust it up or down. 

To manually turn on, go back to front screen, move to RHS to select the DHW side of the screen and press the power button to turn on.

@old_scientist well that's solved one problem 😁

I've raised it to 50C and could feel water circulating in the coil pipework but after a minute the 3 way valved closed. 

Curious. 

Posted by: @bontwoody

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I've raised it to 50C and could feel water circulating in the coil pipework but after a minute the 3 way valved closed

Could it be looking for higher DT?  But this makes no sense when the ft is so low, it only makes sense once the ft has been raised.  Something odd!

@jamespa logically if the Samsung is turning things off it only has four inputs. The cylinder temperature, flow and return temperatures and flow rate. Unless I've missed something?

Posted by: @bontwoody

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@jamespa logically if the Samsung is turning things off it only has four inputs. The cylinder temperature, flow and return temperatures and flow rate. Unless I've missed something?

Agreed 

Does Samsung have any kind of 'stream of consciousness' real time monitoring telling you what it's currently doing?  My Vaillant does and my installer used it to confirm his suspicions of a blocked filter

@jamespa Not the Samsung but I have openenergy monitor so I can see flow rate and flow and return temperatures. The cylinder temp is on the Samsung controller and way below the required temperature so I can't see how it could be that. Im mystified at the moment.

Posted by: @bontwoody

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@jamespa logically if the Samsung is turning things off it only has four inputs. The cylinder temperature, flow and return temperatures and flow rate. Unless I've missed something?

Agreed.

Posted by: @bontwoody

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Not the Samsung but I have openenergy monitor so I can see flow rate and flow and return temperatures. The cylinder temp is on the Samsung controller and way below the required temperature so I can't see how it could be that. Im mystified at the moment.

Definitely not the cylinder temp, as the DHW cycle would not start if the cylinder was already at temp (or within hysteresis), and certainly would not cause it to end so quickly.

Assuming your flow rates are also OK, as limited flow rate will cause an error on the controller so we'd know about that from the error code and system stop state.

Which only leaves flow and return temps. I wonder if the return temp is above the flow temp, and that could be causing it to shot off? If the cylinder is already at 30C, and LWT from a cold start is below that (for example 20C), the flow of water will be warmed as heat is transferred from the hotter DHW cylinder to the circulating water in the coil so the retuning water may initially be hotter than the LWT, causing a near immediate shut down? Could that be a thing??

Posted by: @old_scientist

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Which only leaves flow and return temps. I wonder if the return temp is above the flow temp, and that could be causing it to shot off? If the cylinder is already at 30C, and LWT from a cold start is below that (for example 20C), the flow of water will be warmed as heat is transferred from the hotter DHW cylinder to the circulating water in the coil so the retuning water may initially be hotter than the LWT, causing a near immediate shut down? Could that be a thing??

Crazy if that is the case.  It will surely be the norm if you try to top up a partially heated cylinder in summer when the ft will start out cold compared with the cylinder temp.