classic drivel
classic drivel
But a diverter is either in the HW only or the CH only position. There is no mid position, so the last sentence does not make sense.on the avantas when you wire the controls to the pcb board it has 2 connections for the cylinder stat and for the heating stat. when only the hot water stat calls for heat and the diverter valve confirms that hot water only is being heated then it runs at the maximum temp that you have set the boiler at. if the controls call for both heating and hot water or heating only then it relies on the weather compensation.
At last, after 16 replies and three requests, I have a sensible answer.sorry should have read mid position valve not diverter valve.
I have seen this in operation and if you still don't believe then give a broag a ring.
I think you will find the diverter valve is part of a controlled temperature zone DH, In weather compensation it only allows a set point into the heating circuit.
I would have though a rotary shoe or needle valve would be the norm ESBE come to mind.
At last, after 16 replies and three requests, I have a sensible answer.sorry should have read mid position valve not diverter valve.
I have seen this in operation and if you still don't believe then give a broag a ring.
However, this begs the question: why do Broag only show diverter valves when weather compensation is being used? The only time they use a mid position valve, Y plan, they use 230v switching with no weather compensation.
if im not mistaken the 18V is an open vent heat only boiler. The weather compensation option is only avaliable when using a system boiler or combi. If on a system boiler then you have to use a DHW prioity diverter valve instead of y plan or s plan.
if im not mistaken the 18V is an open vent heat only boiler. The weather compensation option is only avaliable when using a system boiler or combi. If on a system boiler then you have to use a DHW prioity diverter valve instead of y plan or s plan.
You are correct in saying the 18v is open vent. However it can be set up for weather comp, we have been fitting them that way for some time. Funnily enough, before Big Burner decided it was his idea.
I don't want to use a diverter valve but a mid-position with weather compensation. However, according to the wiring diagrams, this is not possible. Also, from what you and others have written, the boiler will be in weather comp mode whenever heating is called for, i.e. heat only and mid-position. This would not be any good as the hot water would never get heated if the weather comp set the flow temp below, say 60.The boiler works, in your desired config, as a hot water priority.
It switches out of WC mode when the Programmer is energised for HW and the cyl stat is calling for heat. The boiler is then in standard modulating mode until the cyl stat says HW is satisfied.
When it has completed the HW heating it reverts to WC mode thereafter if there is a heating demand.
That answers another question! I was wondering if the weather compensation would work with the PI control of the CM900 series.You do not need to use Opentherm controls to get this functionality. We have used Honeywell CM907s to good effect.
The Biasi M110-32 is a Band A combi with weather compensation built in which only needs a 10 K NTC outside sensor rather than an expensive and complicated controller.
I fit them with both inside/outside sensors which gives better control.
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