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I would really appreciate some information on the correct operation of this system. The system has two temperature controls - one for the maximum hot water temperature and one for the central heating temperature. The manual (http://www.vaillant.co.uk/stepone2/data/downloads/19/43/00/838402_06.pdf ) clearly shows these being set independently and, for example, shows the CH control set to minimum for summer use while the HW is set at a normal temperature. If I set my boiler like this, there is no hot water.
On my system, which was fitted just before the weather turned cold, I found that if the max CH temperature was set to low, then the maximum HW temperature acheived was low as well regardless of how the max HW temperature control on the boiler was set. The HW control seemed to do nothing. Subsequently I have found that HW temperature control really does do nothing. For HW production I have to have the max CH control turned up appropriately and today have had plenty of hot water with the HW control turned off! Set this way the "hot water supply active" icon is not seen. I have never seen the flashing hot water icon supposed to indicate heating demand from the cylinder regardless of how the HW control is set.
The first question is what do these separate controls actually do - a system boiler has only one output with HW and CH being separated by the zone control valves, not two outputs like a combi, so how can the boiler set different HW and CH maximum temperatures?
Assuming that the controls are supposed to operate independently as shown in the manual, how could my system be behaving as it is? Could it have been wired incorrectly so that the zone valves operate properly but that the only control input to the boiler is for CH? Might this be why the flashing hot water icon indicating heating demand from the cylinder has never been seen?
Thanks for any advice.
On my system, which was fitted just before the weather turned cold, I found that if the max CH temperature was set to low, then the maximum HW temperature acheived was low as well regardless of how the max HW temperature control on the boiler was set. The HW control seemed to do nothing. Subsequently I have found that HW temperature control really does do nothing. For HW production I have to have the max CH control turned up appropriately and today have had plenty of hot water with the HW control turned off! Set this way the "hot water supply active" icon is not seen. I have never seen the flashing hot water icon supposed to indicate heating demand from the cylinder regardless of how the HW control is set.
The first question is what do these separate controls actually do - a system boiler has only one output with HW and CH being separated by the zone control valves, not two outputs like a combi, so how can the boiler set different HW and CH maximum temperatures?
Assuming that the controls are supposed to operate independently as shown in the manual, how could my system be behaving as it is? Could it have been wired incorrectly so that the zone valves operate properly but that the only control input to the boiler is for CH? Might this be why the flashing hot water icon indicating heating demand from the cylinder has never been seen?
Thanks for any advice.
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