classic drivel 
Aavantaplus control systems - a question for Bigburner
- Thread starter D_Hailsham
- Start date
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B
BigBurner
classic drivel
I agree, total 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.
I am still waiting for evidence, from Bigburner, SNB or anyone who knows, that the boiler switches to max power when there is a call for hot water. (I am, of course, talking about the 18V heat only boiler.)
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At last, after 16 replies and three requests, I have a sensible answer.
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.
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.
I would have though a rotary shoe or needle valve would be the norm ESBE come to mind.
System option 5 Doitall.
Which is what (I think) the discussion is refering too.
A mid position valve is hardly going to work as you don't want (compensated) warm water flowing to the hot water cylinder.
Perhaps you are not reading our posts correctly, D_H.
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.
You do not need to use Opentherm controls to get this functionality. We have used Honeywell ST9400C and CM907s to good effect, as Opentherm controls don't tend to be as easy to use (being earlier generation typically). I can see Opentherm would give slightly more efficiency but at the expense of being understood by our customers.
You asked whether a standard three port valve can be used and we found that it will only work with a three wire spring return divertor valve. The spring return can be either biased to the HW or CH port because there is a Xover relay on the PCB, which, as mentioned earlier, is not referred to in the manual.
Does this answer your question?
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.
You do not need to use Opentherm controls to get this functionality. We have used Honeywell ST9400C and CM907s to good effect, as Opentherm controls don't tend to be as easy to use (being earlier generation typically). I can see Opentherm would give slightly more efficiency but at the expense of being understood by our customers.
You asked whether a standard three port valve can be used and we found that it will only work with a three wire spring return divertor valve. The spring return can be either biased to the HW or CH port because there is a Xover relay on the PCB, which, as mentioned earlier, is not referred to in the manual.
Does this answer your question?
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.
B
BigBurner
I rang them up.
B
BigBurner
Strange you knew little about the control system and what the boiler was capable of, which puts it way ahead of the competition, like Vaillant. Using one on UFH directly can save great expense. Use a 30C combi on UFH and much savings in thermal stores, etc. And a system that is cheap to run.
The only cheap boiler I know of with weather compensation is a BIASI model, but they do not sell it as a weather compensation model and do not sell the outside weather sensor. However someone on this forum realised a standard BIASI temperature sensor was of the same range, so putting one of these in weatherproof box would do.
//www.diynot.com/forums/viewtopic.php?t=102536
There may be models by Heatline (who have OpenTherm controls on some models) and ECA using weather compensation. Others may tell.
The only down side about these Avantaplus boilers is that they only modulate down to around 6kW, while the likes of MAN drop to approx 3kW.
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.
This model will also directly supply under floor heating without the need for pumped loops. They will acurately control the flow to below 25 °C.
Biasi is now under new UK management and I am expecting them to be repositioning themselves in the marketplace.
Hopefully they may soon be selling the remote control unit for their boilers which also allows the boiler diagnostic log to be interrogated.
Tony
I fit them with both inside/outside sensors which gives better control.
This model will also directly supply under floor heating without the need for pumped loops. They will acurately control the flow to below 25 °C.
Biasi is now under new UK management and I am expecting them to be repositioning themselves in the marketplace.
Hopefully they may soon be selling the remote control unit for their boilers which also allows the boiler diagnostic log to be interrogated.
Tony
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.
That answers another question! I was wondering if the weather compensation would work with the PI control of the CM900 series.
B
BigBurner
Do they now sell the outside weather compensator temp' sensors?
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