Vaillant "D" Settings help

[pd1971]

Hi Guys

Will try to respond to all questions -sorry if I miss any answers

CH is on for about 1.5 hours in the morning then about 7-8 hours after 16:30
Sometimes left on during the day at 18°C

HW on for about 1 hour/day

Currently paying

£0.03359 per KW ex vat
£0.3088 ex vat standing charge / day

No higher rate for quarterly useage

working out at about £1.58 ex vat @ 38KW per day

Will monitor usage & do understand you can't really compare day to day useage due to temp differentials but was comparing the usage with a similar day with similar temps outside with settings at 18KW & the new lower setting

System is Open Vent the Cylinder stat is set to 60°C

The boiler Rad water temp is set to 58°C the temperature is fine rooms temps are about 21°C to about 23°C upstairs

When I had the Rad water temp set too high it was very uncomfortable

D2 is set to the default 20 minutes

Dave

 

[scoobydo123]

you do not have separate control over flow temp unless you have the advanced vaillant controls. Your boiler is currently set to below the cylinder stat this means it will struggle to be satisfied what size cylinder and is it fast recovery? Have you tried my test to see if you can produce the short cycling issue.

 

[pd1971]

As far as I'm aware the water temp cannot be controlled by the 418's top HW dial - this is what I was told by the installer? - I just have the cylinder stat set to 60°C

From the label is states - supercal Indirect with Econoplus - 117L Capacity

So are you suggesting to set the Rad water Temp dial to just above 60°C as this is temp needed by the cylinder HW temp?

 

[scoobydo123]

correct if the flow temp is below the cylinder stat it will never be satisfied. You should be able to reduce by 5c on the cylinder stat these can be quite inaccurate so do you have a temp probe as you should be storing water no lower than 55. The hw dial has no function with your current controls. Normally depending on length of run from boiler to cylinder 5c at a min is recommended above hw storage temp.

 

[pd1971]

Ah ok understood - would this be the reason for the short firing even through the HW isn't even on?

Where is the best place to measure the temp on the cylinder?

 

[scoobydo123]

Short cycling is because the 4x series has some very silly logic of burning at 80% of max rated heating load of boiler regardless of d.0. Obviously if everything is up to temp then the boiler will come on at 14.4kw. No chance of it getting the heat away with that amount of energy going into primaries that are already hot. You will find a lot of guys on here wont have it by I am yet to see one that does behave. You can try and get round it by ensuring pump is set 3, pump overrun set to say 15minutes and anticycle set higher. That way after the cycle you might get rid of enough heat but very much doubt it with the flow set slow low. Let me guess here the boiler come on and the temp overshoots your target flow rate within 8 seconds or so. You will find it very difficult to squeeze another 40 seconds out the damn thing.

But I thought you had the latest and greatest 4 series this suppose to have enhanced logic but dont tell me they still have this stupid setting. To test rate d.0 at lowest setting and save. Then listen to the boiler when it fires after cycle the boiler will then fire at a perceived higher noise (greater fan speed more gas). Note this is all for the old series so may get shot down if wrong for the new series but day say they have overlooked and not listened to the complaints (there is hope though for the old series as a Dev board has been released).

Stored water temp just measure at the tap with a probe to make sure tank stat is not miles out.

 

[pd1971]

This is the start of the 3rd Year since I had the boiler installed & just been serviced for a 2nd time

Different engineer told me the boiler is kettling which I have heard this noise pretty much from being installed, he suspects the system wasn't flushed properly, as the system was very very dirty from the old boiler.

He had a F22 fault come up when he was there, but didn't say it was an issue.

I've just checked the D36 on the display (hot water flow sensor settling) its showing 0 when then boiler is firing, is this correct?

When I had the boiler installed the engineer put sludge remover in the system & said it was safe to leave it in

The boiler is set to 8KW which is working fine, when it 1st fires it is quiet loud, then drops once it modulates, but it still kettles

I've noticed the flow temp shoots up very, very quickly (not sure if this is normal behaviour

Your thoughts please?

Thanks in advance

 

[Tibbot]

You simply cannot install these boilers on anything other than a clean system. The level of cleansing required on an old system is, in my opinion unachievable for the level cleanliness required.

Unless of course you're lucky enough to have little or no debris in it to start with.

 

[pd1971]

The installer flushed the system for about 3 hours approx. connected to one of the radiators pipework

Piping is microbore

 

[Tibbot]

You can flush it for 3 hours or 3 weeks, it'll make no difference, especially with microbore. If the system is dirty, you'll never get it clean enough to offer a long, blockage-free life to any Vaillant (Giannoni) heat exchanger.

 

[pd1971]

Many thanks

So are you saying it was a bad idea to install a Vaillant Boiler with Microbore?

Is there a solution apart from power flushing with strong chemicals?

 

[Tibbot]

No, I'm saying that with waterways as narrow as a few mm as well as other design features, that heat exchanger is easily blocked.

Systems piped with microbore are also hard to flush.

 

[ScottishGasMan]

Leaving sludge remover in is not an option, so straight away your system has not been flushed correctly.

As said microbore systems are hard to clean out. But you can flush any system if you do the correct flush for that system. Powerflushing is simply ineffective as the powerflush pump will never flow enough water through the microbore to shift sludge from the radiators.

Powerflushing or mains flushing the pipe work to ensure the microbore is clean and free from restrictions is ok, but the rads would have to come outside and be flushed manually with a hose.

After the system has been filled/run/emptied enough that there is no more cleanser left (water should be clear AND colourless) then inhibitors can go in.

Kettling since new certainly backs up an improper install. Did they fit a filter on the heating system? While not an excuse not to flush correctly, a good filter on the return to the boiler can aid in preventing further buildups in the system and boiler coils.

I'd also refer you to your installation instructions to see if the Cold feed and Open vent pipes from the header tank (if you still have one) are correctly fitted as per the diagram.

D36 applies to hot water rate on combis and has no meaning to your boiler.

Was the pump renewed when the boiler was fitted? see so many of these fitted on systems with 30 year old pumps that just dont have the strength to flow the correct water rate through the main heat exchanger (which is quite restrictive) and the microbore system.

 

[pd1971]

Leaving sludge remover in is not an option, so straight away your system has not been flushed correctly.

As said microbore systems are hard to clean out. But you can flush any system if you do the correct flush for that system. Powerflushing is simply ineffective as the powerflush pump will never flow enough water through the microbore to shift sludge from the radiators.

Powerflushing or mains flushing the pipe work to ensure the microbore is clean and free from restrictions is ok, but the rads would have to come outside and be flushed manually with a hose.

After the system has been filled/run/emptied enough that there is no more cleanser left (water should be clear AND colourless) then inhibitors can go in.

Kettling since new certainly backs up an improper install. Did they fit a filter on the heating system? While not an excuse not to flush correctly, a good filter on the return to the boiler can aid in preventing further buildups in the system and boiler coils.

I'd also refer you to your installation instructions to see if the Cold feed and Open vent pipes from the header tank (if you still have one) are correctly fitted as per the diagram.

D36 applies to hot water rate on combis and has no meaning to your boiler.

Was the pump renewed when the boiler was fitted? see so many of these fitted on systems with 30 year old pumps that just dont have the strength to flow the correct water rate through the main heat exchanger (which is quite restrictive) and the microbore system.

Many thanks ScottishGasMan....

Before they came to install I took off all the rads outside with a hose & flushed them through, as I knew how much sludge there would be.

I drained the system 4 times so the water was clear before the install

The pump I replaced, with a brand new Wilo Smart Pump before the install, as the old one had a leak

The only thing that wasn't replaced is the motorised valve

A TF1 Filter was fitted to the flow pipe for 1 day, then I got the installer back as I wasn't happy, as I had asked for it to be fitted to the return as it really should be.

The water colour is light brown but this could be down to the sludge remover that was left on the system as they said it was fine to do so

Just taken some liquid out of the TF1

The installer is an accredited Vaillant installer so I got a 7 year warranty

Should I be getting the original installer back to resolve this, as when I called Vaillant about this they weren't interested apart from giving me the area mangers phone number who hasn't called back as yet.

They said I wouldn't be covered under warranty if the H/E was blocked due to a bad install

May need to go through small claims, but need to be able to prove that it was don't to poor installation.

Do you suspect the boiler is kettling due to sludge?

Thanks again for your advise

 

[pd1971]

Video of the boiler firing, sounds louder than it is due to my my phone's mic, but you get the idea

After 1 minute the boiler modulates down then quietens to 8KW

https://www.youtube.com/watch?v=e5T74L-N0Gg