Vaillant VRC 430f cycling issues - a solution?

[Tipper]

It's going into anti-cyling mode.

The factory seeting for this is way too generous imho and reducing it drastically helps. On my 937 I think this is setting d.2.

In addition some Ecotech boilers fire to much on start-up and this causes anti-cyling to kick in.

I have 4 Ecotech Plus boilers at various properties, 2 x 824, 1 x 831 and 1 x 937 and all start up in different styles. Some light up at low heat and then ramp up after a period and some light up on high heat and ramp down.

I assume this is because of software changes depending on the build date. Either that or more that one has the same fault.

 

[David937]

It's going into anti-cyling mode.

The factory seeting for this is way too generous imho and reducing it drastically helps. On my 937 I think this is setting d.2.

It might not be anti-cycling, could be the 'pump blocking'

If the flow target temperature is achieved for a longer period of time, the heating is switched off for the prescribed pump blocking time (depends on the external temperature)

I have seen mine do this occasionally, as soon as the target flow temp is reached, the target flow temp drops to 0 and the pump runs for a while and then it continues heating as normal afterwards, haven't a clue why Can't say I would notice it if I wasn't monitoring the heating when it came on. I know it's not anti-cycling as you don't get the flashing radiator symbol.

 

[Modokon]

The difference comes in the start up fan rpm and ignition burn time being different for an ecoTEC 600/800/900 series to a 400 series. Different fan and gas valve. This is makes the 428/38 over shoot really badly when low flow temperatures are requested by the 430/392.

Ignition rate is approx 80% of appliance full rating for 45 secs on a 400 series ecoTEC, irrespective of D.0.

Mr.831Bunny
Not so, by my and at least one others observation. I can clearly hear a difference in fan speed and observe different water rate changes on the 428 if I set d.0 to 12, 18 or 22 etc.
You may be the Vaillant-master, but you are mistaken on this issue.

 

[Modokon]

The difference comes in the start up fan rpm and ignition burn time being different for an ecoTEC 600/800/900 series to a 400 series. Different fan and gas valve. This is makes the 428/38 over shoot really badly when low flow temperatures are requested by the 430/392.

Ignition rate is approx 80% of appliance full rating for 45 secs on a 400 series ecoTEC, irrespective of D.0.

I also think the 400 series is a noisy, cheap piece of rebadged Glowworm crap. With wonders of hindsight I should have gone for a sealed system and a decent Vaillant boiler. Pipes under screed persuaded me not to.

 

[UpgradeME]

I also think the 400 series is a noisy, cheap piece of rebadged Glowworm crap. With wonders of hindsight I should have gone for a sealed system and a decent Vaillant boiler. Pipes under screed persuaded me not to.

A little bit of research reveals the following:

2001 - Vaillant Group purchase Hepworth plc and with it, take ownership of the Glow-worm brand.

Sept 2006 - Vaillant launch ecoTEC Plus 400 series (Press Release)

March 2007 - Glow-worm launch Ultracom hxi models (Press Release)

My own anecdotal view is that the Ultracom hxi models are a cut-down version of the Vaillant ecoTEC plus 400 series, not the other way around! It makes sense to re-use the same design's for a budget model, it happens in a lot of industries... Take model 1 (Vaillant), trim away as much cost as possible (lower cost materials, features, cosmetics etc) and market under a different brand name as model 2 (Glow-worm).

 

[Gary27]

Can I confirm some findings on the matter of cycling, and get it straight in my head whet is happening.

When the system is cold, the system fires up, runs at a high setting (I assume d0 related) and brings the flow d40 up to flow temp target.

At this time d41 will be some way behind d40 approx 20c below.

As d40 is now at target temp it modulates down to maintain d40 at target temp but at the same time d41 is slowly increasingp. As d41 approaches d40 heat required falls so system continues to modulate down.

Now my problem!!!!

As d41 increases, d40 starts to rise unless the system can modulate down to a lower enough output to stop this. My problem appears that it cannot modulate low enough so the system shuts down.

Temp then falls rapidly and about 1-2 mins later system refires at highish output and quickly exceeds target temp and the system gets into a cycle.

Is this a correct explanation of what is happening. I have raised minimum temp (50c) which helps a bit and lowered d0 which helps a bit. I can force it out of the cycles by temporally raising min temp.

Is there anything else I can do. (ecoTEC 418)

 

[Gary27]

Can I confirm some findings on the matter of cycling, and get it straight in my head whet is happening.

When the system is cold, the system fires up, runs at a high setting (I assume d0 related) and brings the flow d40 up to flow temp target.

At this time d41 will be some way behind d40 approx 20c below.

As d40 is now at target temp it modulates down to maintain d40 at target temp but at the same time d41 is slowly increasingp. As d41 approaches d40 heat required falls so system continues to modulate down.

Now my problem!!!!

As d41 increases, d40 starts to rise unless the system can modulate down to a lower enough output to stop this. My problem appears that it cannot modulate low enough so the system shuts down.

Temp then falls rapidly and about 1-2 mins later system refires at highish output and quickly exceeds target temp and the system gets into a cycle.

Is this a correct explanation of what is happening. I have raised minimum temp (50c) which helps a bit and lowered d0 which helps a bit. I can force it out of the cycles by temporally raising min temp.

Is there anything else I can do. (ecoTEC 418)

Is there no Valliant experts out there that can run there eye over what I am finding?

 

[chrisfi]

It might not be anti-cycling, could be the 'pump blocking'

If the flow target temperature is achieved for a longer period of time, the heating is switched off for the prescribed pump blocking time (depends on the external temperature)

I agree with David. The setting for 'pump blocking' or as on my VRC 430 'pump delay time' will shut the boiler down from time to time and this is on top of the boiler shutting down when the flow temp overshoots or flow/return difference becomes too small.

My suggestion in addition to the settings from the OP would be to set the VRC 430 'Max pump blocking time' or 'pump delay time' on screen C21 to 'off'.

I have and it has greatly reduced the cycling on my system.

 

[Modokon]

Can I Is there anything else I can do. (ecoTEC 418)

Is there no Valliant experts out there that can run there eye over what I am finding?

Gary
I am no expert, but have plenty of experience with cycling. A few questions/suggestions:
1. What is d.0 at the moment? Try 15 or 12. How many rads?
2. What speed is your CH pump set at? It should be max speed, (not anything clever like Grundfos Alphas are prone to do!) as that pushes the water through the exchanger more quickly, so preventing the opportunity for d.41 to get too high.
3. Is your system nice and clean and flushed? You want to be sure that the water is flowing through.
PS. Could you try and set the min temp in screen C9 to 55degC to see if that helps?
RSVP with your findings.

 

[Modokon]

I also think the 400 series is a noisy, cheap piece of rebadged Glowworm crap. With wonders of hindsight I should have gone for a sealed system and a decent Vaillant boiler. Pipes under screed persuaded me not to.

A little bit of research reveals the following:

2001 - Vaillant Group purchase Hepworth plc and with it, take ownership of the Glow-worm brand.

Sept 2006 - Vaillant launch ecoTEC Plus 400 series (Press Release)

March 2007 - Glow-worm launch Ultracom hxi models (Press Release)

My own anecdotal view is that the Ultracom hxi models are a cut-down version of the Vaillant ecoTEC plus 400 series, not the other way around! It makes sense to re-use the same design's for a budget model, it happens in a lot of industries... Take model 1 (Vaillant), trim away as much cost as possible (lower cost materials, features, cosmetics etc) and market under a different brand name as model 2 (Glow-worm).

Research? Try my empirical data. I have had both boilers. The Glow-worm was a heck of lot quieter. The Vaillant is so much louder it's hard to understand why. The installer said every one he had installed was loud. The 4xx is also very unforgiving, requiring a fast, high volume of water.
The glow-worm just plain worked. No fuss, no drama. It was invisible, which is the best compliment I can pay to it.

 

[Gary27]

Can I Is there anything else I can do. (ecoTEC 418)

Is there no Valliant experts out there that can run there eye over what I am finding?

Gary
I am no expert, but have plenty of experience with cycling. A few questions/suggestions:
1. What is d.0 at the moment? Try 15 or 12. How many rads?
2. What speed is your CH pump set at? It should be max speed, (not anything clever like Grundfos Alphas are prone to do!) as that pushes the water through the exchanger more quickly, so preventing the opportunity for d.41 to get too high.
3. Is your system nice and clean and flushed? You want to be sure that the water is flowing through.
PS. Could you try and set the min temp in screen C9 to 55degC to see if that helps?
RSVP with your findings.

Thanks, I am starting to get the hang of this now, all your suggestions help and with the cold weather it seems to be working fine, i have been able to curve the down to 1.8, this give me a flow temp of about 62 in the cold and I have 55 set as minimum for the warmer weather.

 

[Tipper]

Turned my Vaillant 937/430f combo on to 'holiday' whilst I had a few days away and it's taken an age, well a good few hours, to get the house back up to temperature! Grrrr.

Is there a general concensus as to the best settings for the 430f? Is it what was posted a few threads ago by Modokon? Can someone list there 430f settings?

I see now that I have upgraded this year to a 430f Vaillant have produced a new model - 470f? What's the difference? Can the software in my 430f be upgraded somwhow?

I really do find Vaillant's programmer settings confusing!!!

 

[David937]

I guess it took a while as the building fabric also cooled down maybe?

I have my VRC430f set to:

50ºc Minimum flow temperature.
2.6 Heating curve.
Thermostat room temperature control.

It works absolutely fine TBH, everywhere in the house is nice and warm and it doesn't cycle much either, maybe just a little when it's fairly mild outside and the room temperature is approaching the set point.

The curve was initially set at 2.8 which caused a bit of overshoot, reduced to 2.7 which was better but still a bit of overshoot at times, now at 2.6 which works perfectly. It's simply left well alone now to do what it has to do, only time it is touched is to change a heating programme or to bring the heating on earlier if it's very cold.

 

[Gary27]

I guess it took a while as the building fabric also cooled down maybe?

I have my VRC430f set to:

50ºc Minimum flow temperature.
2.6 Heating curve.
Thermostat room temperature control.

It works absolutely fine TBH, everywhere in the house is nice and warm and it doesn't cycle much either, maybe just a little when it's fairly mild outside and the room temperature is approaching the set point.

The curve was initially set at 2.8 which caused a bit of overshoot, reduced to 2.7 which was better but still a bit of overshoot at times, now at 2.6 which works perfectly. It's simply left well alone now to do what it has to do, only time it is touched is to change a heating programme or to bring the heating on earlier if it's very cold.

But won't a heating curve of 2.6 nearly always exceed 65c which will not be good for condensing. I use 55c min temp and 1.8 curve to keep the temp down. It's not easy to get efficiency and ease of use.

 

[David937]

The heating curve of 2.6 suits the house which has 9" solid walls so looses a lot of heat. Once the house is up to temperature, the flow temperature won't be exactly what the heating curve dictates because it also takes room temperature in to consideration.

It has only really been over 65ºc in the recent cold weather on initial start up.