How about an anwer or response to my question Bunnyman? (afterall, I did provide the answer the this weeks trivia! lol)
Vaillant Issues
- Thread starter vince101
- Start date
How about an anwer or response to my question Bunnyman? (afterall, I did provide the answer the this weeks trivia! lol)
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ALEC1
Sorry Bunnyman no offence ever meant to a man on the tools...
I've been suffering from similar symptoms to Vince101 (boiler cycles when driving HW only) and would like to hear if replacing the HW cylinder fixes Vince101's problems.
I don't believe the story of the pump being too slow, given that the CH-only scenario works fine. The "resistance" of the CH pipework loop should be higher than the shorter HW pipework loop. So if the pump is fast enough for CH, then I think it's fast enough for HW.
Also, I don't believe the story about the boiler being oversized for a HW-only scenario. This is a common use-case that the boiler will have been tested with. Boilers are designed to modulate down to cope with scenarios where not as much heat is needed.
My theory is that it's all caused by the cylinder not extracting sufficient heat. This can be caused by either:
- a short coil in the old cylinder
- limescale inside/around the coil acting as an insulator
- limescale inside the coil reducing the flow rate to the boiler
Please let us know how it goes.
I don't believe the story of the pump being too slow, given that the CH-only scenario works fine. The "resistance" of the CH pipework loop should be higher than the shorter HW pipework loop. So if the pump is fast enough for CH, then I think it's fast enough for HW.
Also, I don't believe the story about the boiler being oversized for a HW-only scenario. This is a common use-case that the boiler will have been tested with. Boilers are designed to modulate down to cope with scenarios where not as much heat is needed.
My theory is that it's all caused by the cylinder not extracting sufficient heat. This can be caused by either:
- a short coil in the old cylinder
- limescale inside/around the coil acting as an insulator
- limescale inside the coil reducing the flow rate to the boiler
Please let us know how it goes.
gypsy182...I was about to give an update so you've prompted me.
I've just replaced an old 120 litre cylinder with a 140 litre version that has high recovery. (Range Ultracal). I've gone slightly over the top on that as the family is growing and needs more water etc. I reckoned the heating time would be less that 15mins and most importantly is rated around 24kW so should be able to cope with D0 setting of 22. Internal surface area was 1.23 m2 which is massive. I could have gone with a lower spec recovery time but didn't want to take that chance.
I couldn't see very clearly inside the old cylinder except to see very few coils.
The previous cylinder leaked very slightly on pump speed 3 that meant I had to limit to speed 2 which meant some S53 problems. (Pump is DAB VA 55/130) Now I can use that setting that gives ~3.5m head at 20 litre/min well above the manual minimum setting.
The end result...no problems whatsoever!
HW and CH now works great with no S53 problems. D41-D40 is about 15 degC
HW indeed gets to temp within 15 mins and no cycling until its up to temp. D41-D40 is also about 15 DegC.
In summary I maybe have been unfair in criticising Vaillant for all the problems that I had. Most of the problems resulted from the nupty installer...and it was only with the help of this board that I was able to resolve the numerous issues.
Best of luck!
I've just replaced an old 120 litre cylinder with a 140 litre version that has high recovery. (Range Ultracal). I've gone slightly over the top on that as the family is growing and needs more water etc. I reckoned the heating time would be less that 15mins and most importantly is rated around 24kW so should be able to cope with D0 setting of 22. Internal surface area was 1.23 m2 which is massive. I could have gone with a lower spec recovery time but didn't want to take that chance.
I couldn't see very clearly inside the old cylinder except to see very few coils.
The previous cylinder leaked very slightly on pump speed 3 that meant I had to limit to speed 2 which meant some S53 problems. (Pump is DAB VA 55/130) Now I can use that setting that gives ~3.5m head at 20 litre/min well above the manual minimum setting.
The end result...no problems whatsoever!
HW and CH now works great with no S53 problems. D41-D40 is about 15 degC
HW indeed gets to temp within 15 mins and no cycling until its up to temp. D41-D40 is also about 15 DegC.
In summary I maybe have been unfair in criticising Vaillant for all the problems that I had. Most of the problems resulted from the nupty installer...and it was only with the help of this board that I was able to resolve the numerous issues.
Best of luck!
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ALEC1
installers are only as good as he infornation they are supplied with...you cant blame the installer!
If you use the vr 65 control centre, you can range rate in hot water to match an old cylinder with a small coil...
So no Vailliant engineering shoild not get the flack, but may be the UK trainig and technical departments should
If you use the vr 65 control centre, you can range rate in hot water to match an old cylinder with a small coil...
So no Vailliant engineering shoild not get the flack, but may be the UK trainig and technical departments should
Vince 101 did you upgrade/ change or alter the tankstat when you changed cylinder? This may have given you your perceived cure. Granted your cylinder coil may have helped but there are fundamental flaws in the start up routine that only with the correct settings on the boiler and a lot of luck can you get round.
That's great to hear. I knew it would be the cylinder 
So looks like I'll be replacing mine too. The Range Ultracal looks like it does the job. The Range brochure says I'll only need an 80l cylinder for my 2 bedroom house, though I think I might overspec it to be on the safe side and go for the 120l Ultracal for £386.
So looks like I'll be replacing mine too. The Range Ultracal looks like it does the job. The Range brochure says I'll only need an 80l cylinder for my 2 bedroom house, though I think I might overspec it to be on the safe side and go for the 120l Ultracal for £386.
scoobydo123
I kept the same cylinder thermostat
I kept the same cylinder thermostat
That's a very broad and unsubstantiated comment ALEC1. I think you'll find that there are many great installers (and S/R engineers) out there that that have sourced and digested their own information and honed their skills without such need as to be spoon fed by others.. On the flip side, there are many that HAVE received far more information and training and yet still continue to fail as a quality, skilled engineer, as it largely depends on the individual and the ability to "LISTEN"....... learn, digest and retain...
Curious..... Where do you place yourself??
And how have you managed to come to this conclusion?
Oh god Alec at it again go an fit something constructive with ur talents maybe Ferroli
A
ALEC1
well its just frustrating that vaillant say various things that are blatently misleading...
1) the mixing module does not work with UFH - it does
2) vr10 doesn't work on vented cylinders - it does
3) vaillants instructions are misleading too, and in some case miss essential detail...I am referring to the instructions of the low loss header sensor. Then theres the fact that no where does it explain the benefits of this sensor...
All this reflects on installers, the manufacturers just hide behind that...
1) the mixing module does not work with UFH - it does
2) vr10 doesn't work on vented cylinders - it does
3) vaillants instructions are misleading too, and in some case miss essential detail...I am referring to the instructions of the low loss header sensor. Then theres the fact that no where does it explain the benefits of this sensor...
All this reflects on installers, the manufacturers just hide behind that...
A
ALEC1
I let my clients decide on this..my work is referral and some boiler manufacturer listings...
but reflect on this Mr V..of about 100 900/800 and 600 series boilers vaillant have been to one, about a faulty pressure sensor... a known issue! People also approach me to sort out compatibility issues with UFH and up grade controls.
I don't put the high reliability down to anything I have done, the only thing that I do that others do not is install vaillants own controls usually the weather compensation.
Vaillant boilers, installed as they are installed in Germany, are fine reliable boilers that will do the service. People get issues with them, in my opinion, because they compromise the technology by using numpty on-off controls...
I fail to see how on/off controls affect reliability?
@ ALEC1 in reference to range rating for HW coil all good as long as it doesn't cycle once. The issue comes around if the boiler does cycle and flow is set reasonably high. The anti cycle timer cannot be adjusted high enough to stand a chance of the boiler getting to the range rated setting as it chooses to ignore the setting for the first 50 seconds. I am currently evaluating getting advanced controls for my set up 428 and Megaflo (145L). Have been looking at the new vrc470 but they seem to have recently added that it needs the vr61 or vr66 I though the vr 65 was required for this?
Vince jusr re-read your post, yes the key to your success is that you make it to cylinder satisfied without a cycle hence you dont hit the software bug. Out of interest what do you have your d.2 setting set to and also flow temp. Congrats on getting your system sorted.
Vince jusr re-read your post, yes the key to your success is that you make it to cylinder satisfied without a cycle hence you dont hit the software bug. Out of interest what do you have your d.2 setting set to and also flow temp. Congrats on getting your system sorted.
What a laugh reading all the threads.
Vaillant 400 range is a cracking boiler when fitted correctly, and doesn't matter if vaillant controls are fitted or not.
Problems this range of boilers suffer from is undersized pipework on flow and return ( yes they are 22mm tails on boiler but for 428 and 438 should have 28mm primary circs)
Second problem is sh*t in the heat exchanger ( No it does not come pre fitted in the boiler out the box )
3rd problem mainly on the 418 as few installers actually gas rate they don't realise that the 18kw boiler they have fitted can actually be running at close to 21kw causing a noise issue that can easily be corrected through the 4 button display in less that a minute.
Vaillant 400 range is a cracking boiler when fitted correctly, and doesn't matter if vaillant controls are fitted or not.
Problems this range of boilers suffer from is undersized pipework on flow and return ( yes they are 22mm tails on boiler but for 428 and 438 should have 28mm primary circs)
Second problem is sh*t in the heat exchanger ( No it does not come pre fitted in the boiler out the box )
3rd problem mainly on the 418 as few installers actually gas rate they don't realise that the 18kw boiler they have fitted can actually be running at close to 21kw causing a noise issue that can easily be corrected through the 4 button display in less that a minute.
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