Vaillant F83

[Harry Bloomfield]

No hot water this afternoon. Vaillant 418 EcoFIT Pure, open vented system, 3-port valve, VRC 470F, VR 65, VR 10 thermistor sensing cylinder temperature.

Reset it to clear fault, and try again , and now getting the near constant pause symbol, though had it actually purge, and fire the boiler briefly, a few times. Checked loft header tank, 4" of water, checked flow and return sensors d40 d41, and they agree with my add-on pipe temperature sensors. 3-port seems to respond correctly.

Throughout, I have not heard the circulation pump run, or seen it's LED come on. Pump is fed/powered directly by the boiler. My next stage of investigation, is to power the pump up from a 13amp socket - but not for a couple of days, I am too busy on other things.

Has anyone any alternative diagnostic suggestions?

 

[Johntheo5]

The circ pump is the most likely cause IMO, the "insufficient water in product" is generally triggered by the non detection of a slight rise in pressure when the pump starts, on boilers with a pressure gauge, you will see a slight rise in pressure which should be the pump head, could also be a blocked pressure tube but testing your pump first is the way to go.

I see from one of your (2019) posts that you have or had a Grundfos Alpha pump, these should display at least the power in watts and the more modern ones also display the head in M as well I think.

"When the burner starts, the temperature change registered at the flow
and/or return temperature sensor is non-existent or too small.
– Insufficient water in product
– Flow or return temperature sensor not in correct position at pipe"

 

[Harry Bloomfield]

I see from one of your (2019) posts that you have or had a Grundfos Alpha pump, these should display at least the power in watts and the more modern ones also display the head in M as well I think.

No, it was an older Alpha+ it just has a speed setting, and a green LED. I've just got back to it, and my/our diagnosis was correct - the pump is totally dead, powered direct from the nearest socket. Hopefully, it hasn't taken the PCB out.

 

[Harry Bloomfield]

It hadn't taken the PCB out I opted to buy a Wilo Yonos PICO 25/1-6-130, as a cheaper alternative to the Grundfos Alpha, at £120 from the local Screwfix. The Alpha was quiet, always run on minimum, but this Wilo is much quieter, even on maximum power.

I was dreading trying to turn the now 40+ year old pump isolator valves off, but managed it with a bit of struggle, and one still passing a bit of water. The old Alpha pump, now some 20 years old, and only replaced the original, because a new boiler was going in, nowt wrong with the old pump. The longest single task, was working out from the pictograms, how to actually connect the pumps mains supply flex, onto the supplied terminal, screw-less plug. It took the two of us, a solid hour trying to work out, how the spring catches were supposed to grip the flex wires..

On first firing it all up, no boiler faults showed, but setting it to Cylinder Boost, the VRC 470F kept cancelling the Boost, and the 3-port kept rotating to the CH position, with no demand for CH - fooling me into thinking there might be yet a second issue. So with the indoor temperature at 24C, I wacked it up to 30C, and the boiler at last fired up. Turned back down, and Cylinder Boost pressed, it accepted it, and heated the cylinder of water, as just normal. I guess it just had some air trapped somewhere.

I just have to fathom out now, how to configure the pump settings - I HATE PICTOGRAMS..

 

[Johntheo5]

I have one of those Pumps, Harry, installed well over 6 years ago, IMO, a Rolls Royce in that you can set the head in 0.1M increments between 0.5M & ~ 5.5M in either CP (constant pressure) or PP (proportional pressure) modes, the three settings in the middle are the conventional constant speed setting, I is 2.0M, II, 3.8M & III, 5.8M, II is probably a good initial setting.
Turning the setting knob to the left of the constant speed settings is the PP mode, every time you stop turning it, it displays the set pressure by flashing for a few seconds, CP mode is to the right of the constant speed settings, I have mine set to a PP setting of 4.6M which gives a actual head of ~ 3.5M at 22/24W with the the 8 TRVd rads fully calling, (TRVs), the power then falls off to ~ 14/16W as the TRVs throttle down. My pump gives just the power W but yours should give the flowrate as well, in m3/hr.

 

[Harry Bloomfield]

Turning the setting knob to the left of the constant speed settings is the PP mode, every time you stop turning it, it displays the set pressure by flashing for a few seconds, CP mode is to the right of the constant speed settings, I have mine set to a PP setting of 4.6M which gives a actual head of ~ 3.5M at 22/24W with the the 8 TRVd rads fully calling, (TRVs), the power then falls off to ~ 14/16W as the TRVs throttle down. My pump gives just the power W but yours should give the flowrate as well, in m3/hr.

Thanks, getting I'm somewhere now! Three bed semi, nine rads, all but one with TRV's, open vented, with a 3-port - what would you suggest I set it on, PP or CP please, and at what level?

What does the tiny button, lower left do please? It seems to flash top, middle, then bottom horizontal lines in the display?

 

[Johntheo5]

I would suggest setting it to 3.0M on CP mode (to the right). When its next heating HW cylinder, make a note of the power and flowrate.

The lower left button is for venting the pump, if you keep it pressed for something like 5 secs or so the pump will speed up and down for around 10 minutes I think and then return to its normal mode & setting.