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Hello
Recently moved into a 3bed and having some trouble with the HW, perhaps someone here has some advice. This is my first property with an open-vent system/cylinder/etc, it's been...interesting...to learn about.
Vaillant 418 in heat-only mode (only the lower dial controls temp request), around 160L cylinder (can't find any info on the cylinder, just a quick measurement/calculation for the volume), Y-plan with a Grundfos UPS2 15-50/60 pump set to Speed 3, single old Honeywell stat on the cylinder and a single old Honeywell room stat. Siemens RWB29 programmer, 9 older radiators of various sizes and 2 newer towel radiators (one in each bathroom). Terrace house built in the 80s - I imagine this is a standard heating system for this type of property.
Anyway, at first the 418 would only briefly fire and then go straight to s.53. Barely any HW or CH...took about 9 hours of this behaviour to just warm the cylinder so I figured there was a problem. After browsing this forum I learned about the Vaillant diagnostic codes, d.0 specifically, and saw that my 418 was set to max power and I moved it down.
Setting d.0 to 10 and temp dial to 70C sorted out the CH for the most part...nice long burn of about 30min before it then hit an s.7, then another longish burn after, etc. Radiators nice and warm. Looking at d.40 and d.41 shows a 16C difference between them, I think this is about right?
HW on the other hand is still a problem. Asking for HW kicks of a first burn of about 2min and the flow temp ramps up very quickly before the 418 stops and an s.7 happens, then the burns get shorter and shorter until they're maybe 20 sec burns before the 5min s.7 kicks in, over and over. Difference between d.40 and d.41 with a HW request is 5C. It takes around 3 hours to heat the 160L cylinder to 55C with this behaviour when (ideally) I think it should take less than an hour? Dropping d.0 lower than 10 doesn't seem to help either.
Additionally, when HW and CH are both on, the last few radiators on the circuit don't warm up and the 418 still has the short cycles with s.7. I thought that perhaps this was because now there wasn't enough power being generated for both HW and CH with d.0 at 10 so I experimented with moving d.0 back up, but nothing changes.
It seems as though whatever I do with the HW, the 418 short cycles and s.7 pump overrun status shows up. It's as if there's too much power being supplied to the HW circuit/residual heat from the HW circuit can't be dissipated quickly enough whereas the CH circuit is fine. Is this likely to be some sort of circulation issue with the HW, or are there settings on the 418 which also could account for it?
Thank you!
Recently moved into a 3bed and having some trouble with the HW, perhaps someone here has some advice. This is my first property with an open-vent system/cylinder/etc, it's been...interesting...to learn about.
Vaillant 418 in heat-only mode (only the lower dial controls temp request), around 160L cylinder (can't find any info on the cylinder, just a quick measurement/calculation for the volume), Y-plan with a Grundfos UPS2 15-50/60 pump set to Speed 3, single old Honeywell stat on the cylinder and a single old Honeywell room stat. Siemens RWB29 programmer, 9 older radiators of various sizes and 2 newer towel radiators (one in each bathroom). Terrace house built in the 80s - I imagine this is a standard heating system for this type of property.
Anyway, at first the 418 would only briefly fire and then go straight to s.53. Barely any HW or CH...took about 9 hours of this behaviour to just warm the cylinder so I figured there was a problem. After browsing this forum I learned about the Vaillant diagnostic codes, d.0 specifically, and saw that my 418 was set to max power and I moved it down.
Setting d.0 to 10 and temp dial to 70C sorted out the CH for the most part...nice long burn of about 30min before it then hit an s.7, then another longish burn after, etc. Radiators nice and warm. Looking at d.40 and d.41 shows a 16C difference between them, I think this is about right?
HW on the other hand is still a problem. Asking for HW kicks of a first burn of about 2min and the flow temp ramps up very quickly before the 418 stops and an s.7 happens, then the burns get shorter and shorter until they're maybe 20 sec burns before the 5min s.7 kicks in, over and over. Difference between d.40 and d.41 with a HW request is 5C. It takes around 3 hours to heat the 160L cylinder to 55C with this behaviour when (ideally) I think it should take less than an hour? Dropping d.0 lower than 10 doesn't seem to help either.
Additionally, when HW and CH are both on, the last few radiators on the circuit don't warm up and the 418 still has the short cycles with s.7. I thought that perhaps this was because now there wasn't enough power being generated for both HW and CH with d.0 at 10 so I experimented with moving d.0 back up, but nothing changes.
It seems as though whatever I do with the HW, the 418 short cycles and s.7 pump overrun status shows up. It's as if there's too much power being supplied to the HW circuit/residual heat from the HW circuit can't be dissipated quickly enough whereas the CH circuit is fine. Is this likely to be some sort of circulation issue with the HW, or are there settings on the 418 which also could account for it?
Thank you!