15 Jan 2020
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United Kingdom
I have a Worcester Bosch 35cdi System boiler with optional diverter valve (diverter valve enables it to be used with a hot water cylinder). The control package is via Tado and integrates via the Worcester EMS bus system.
My issue is that when the system is heating the hot water tank, it routinely goes into the temporary error state that indicated that the boiler temperature gradient is too high (the flow is heating up too fast), flow of about 85+ degree. It does this a couple of times and then eventually heats the hot water tank, holding a flow temperature of about 80 degrees.

The pipe run to the hot water tank is reasonably long at about 22m between the boiler and tank.
There are very few settings on the boiler to adjust the hot water function.
I was thinking that the boiler is having difficulty getting a decent flow when on hot water mode. The resistance in the pipes to the hot water tank may be causing the boiler to reduce the pump speed.
I was considering adjusting the pump speed map, to a constant high pressure rather than a modulating high pressure. The down side of this is the heating in the house already works perfectly and I'd like to use the modulation if at all possible.

Is there something I've missed that could stop this initial gradient limit error in hot water mode?
Would limiting the maximum hot water boiler power help?

Any views appreciated!
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