Vaillant boiler issues F28 on ecotec 430 not the normal culprit

[Navi Bhander]

Why do you need two boilers for such a system with 30 kw each running in the same time? As mentioned above to all the others well oversized and get a reliable engineer or perhaps donit via warranty

I honestly don’t know, I have asked the subcontractors that built the property and they said they are variable output so will work load dependant or something along those lines.

Apparently the heat calculation for the house was 57kw and the space worked out best for 2x 30kw.

I’m not sure tbh but it’s been one nightmare.

I’ve had a various gas safe plumbers out, they all looked at the system and said it’s fine and it’s a gas supply to the property issue. I’m sure apart from cadent I’ve paid 3 local firms to come check it.

The last guy checked it and gave me a certificate to say it’s gas safe tested as well and said it’s a supply issue to the meter.

As you can see I’ve been trying to resolve this and was obviously fobbed off by everyone that it’s a supply issue to the house.

 

[Navi Bhander]

I will second the post re Andrew, if anyone can Mr Millward can.

I’ve spoken with him and he’s coming out tomorrow 🙂

 

[gmartine]

If you use Millward do keep us posted, thanks.

 

[Navi Bhander]

If you use Millward do keep us posted, thanks.

Will keep you updated tomorrow.

Just to clarify with one boiler disconnected the issue is still there on the remaining boiler.

When the controller demands heat, the radiator symbol comes up on the boiler, the pump switches on and after 5-10 secs the flame light comes on with the triangle variable display comes on on the minimum setting. It then switches off within 2 secs and then starts up again after 5-10 then continues to run.

It does this most times I look at it, I presume this is an ignition failure?

I understand the boilers may be missing headers etc and I will have this rectified. But I don’t think this or a bigger meter will fix my issue as even with 1 boiler I have the issue.

I’m really hoping Andrew comes in and works his magic, having spent 15 mins on the phone he clearly knows his stuff.

 

[Navi Bhander]

Just a quick update.

Had Andrew over today. Firstly I agree with the other recommendations, he is such a lovely guy and clearly knows his stuff.

To cut a very long story short he identified the lack of low loss header and isn’t convinced pairing the boilers together is the best way. As I have 2 Honeywell evohome systems to cover all the zones and 2 tanks he needs to double check how to integrate everything together.

However none of this is the cause of the F28.

He checked the pressure at each boiler, 24mb standing that drops to 18 on full load of both boilers when in chimney sweep.

He said that’s on the low side but not enough to give the problem I have.

The f28 is ignition failure and luckily it played up once while he was there. The boiler while having 24mb pressure fails to ignite on its first attempt, something it does on every other start up.

He checked the flue pipe, did various tests on the boilers, co2 checks etc and nothing at all.

He’s going to speak with a few Vaillant contacts of his to check as nothing is untoward but yet both boilers display identical issues even when each one is isolated.

As it stands in the past few days the F28 hasn’t come back with 1 boiler running, albeit it may not start on the 1st attempt.

Andrew has also advised to increase the pipe diameter to the boiler to 22mm instead of using a 15mm pipe from the 28mm pipe.

Any other suggestions to what my f28 fault could be?

 

[gmartine]

We sympathise with your frustration but do give him a chance to get back to you and make the necessary changes as occasionally a combination of events especially where electronics and sensors are concerned can lead to anomolies that aren't easily explained by a fault code. With an untracable intermittent fault it may eventually be a case of replacing parts in a systematic semi-educated way which is expensive but still no guarantee. Do continue to keep us updated as we're also on a learning curve albeit at your inconvenience, and goodluck hopefully you won't need it now Andrew is on the case.

 

[Navi Bhander]

We sympathise with your frustration but do give him a chance to get back to you and make the necessary changes as occasionally a combination of events especially where electronics and sensors are concerned can lead to anomolies that aren't easily explained by a fault code. With an untracable intermittent fault it may eventually be a case of replacing parts in a systematic semi-educated way which is expensive but still no guarantee. Do continue to keep us updated as we're also on a learning curve albeit at your inconvenience, and goodluck hopefully you won't need it now Andrew is on the case.

I fully understand intermittent issues and I respect Andrew’s honesty with all the advice. He’s not given up either, so he’s going to contact his Vailliant chap to do some further fault finding and send someone else over too.

The system installation design will be getting fixed regardless, he’s just doing some research into the evohome system to make sure it will all integrate and function better.

 

[gmartine]

I'm reluctant to tread on anybody toes mid-investigation, let it run it's course but this would be my next areas of concern...

Igniter, gas valve and electronics. You never know both boilers could've been installed with faulty igniters, highly unlikely but a cheapish swap out.

 

[Navi Bhander]

I'm reluctant to tread on anybody toes mid-investigation, let it run it's course but this this would be my next areas of concern...

– There’s a problem with the gas supply to the boiler.

– [/s]There’s air in the pipes.

– The pressure of the gas flow is too low.

– Igniter is defective.

– There is a fault in the gas valve.

– Electronics are defective.

The good thing with Andrew was he’s sonopen to ideas he even asked if the forum had suggested anything else!

How would air enter the gas system?

Once the boiler has ignited it’s fine, it doesn’t switch on which brings up the F28.

 

[gmartine]

See above post again Navi, my strike throughs are like your boilers... unpredictable. It sounds like everything has been done with regards to your gas supply, F28 error includes gas + ignition so that side of things require further investigation imo hence recommending the igniter swap out. It may at this point ask be worth asking Vaillant to participate again IF parts are required.

 

[Gasmk1]

See above post again Navi, my strike throughs are like your boilers... unpredictable. It sounds like everything has been done with regards to your gas supply, F28 error includes gas + ignition so that side of things require further investigation imo hence recommending the igniter swap out. It may at this point ask Vaillant to participate again IF parts are required.

can this fault also so be due to ignition lead

 

[gmartine]

Probably about as unlikely as a faulty igniter, no point assuming anything at this stage.

The simultaneous fault occuring in both boilers is the kicker here which is why everybody has concentrated on the gas side of things to date. Could've been a late Friday afternoon at the Vaillant factory when these boilers rolled out, who knows.

 

[Navi Bhander]

See above post again Navi, my strike throughs are like your boilers... unpredictable. It sounds like everything has been done with regards to your gas supply, F28 error includes gas + ignition so that side of things require further investigation imo hence recommending the igniter swap out. It may at this point ask be worth asking Vaillant to participate again IF parts are required.

Yes, Andrew has the same thoughts. He’s asked to get Vailliant back over again to check them.

The only baffling thing was one boiler will never switch off by itself, always both of them together at the exact same time.

But when you’re clutching at straws and have tried everything then sometimes the most unlikely cause can be the cause.

I’m stuck at work today so will call them in the morning and get an engineer out.

 

[gmartine]

The only baffling thing was one boiler will never switch off by itself, always both of them together at the exact same time.

I don't think your boilers have been paired properly so that may cause some issues. It sounds like whoever designed your semi-commercial system has had a go with trying to design/install it by scaling up their domestic knowledge. I'm sure Andrew will get to the bottom of it...eventually.

 

[Jerry]

I look forward to finding out what the fault is.

 

[Aire]

Did Andrew check the termination of the condensates? Both go to the same pipe so if there is a blockage or partial blockage it may cause an intermittent f28 fault code.

 

[Navi Bhander]

Did Andrew check the termination of the condensates? Both go to the same pipe so if there is a blockage or partial blockage it may cause an intermittent f28 fault code.

This was checked by another gas safe engineer before as well. I remember him pouring water down there and stating there definitely was no issue on that side.

Well the one boiler still hasn’t kicked out yet, but when it ignites it will switch off within 2 secs and then fire back up after 5 seconds.

So the confusing bit is the boiler will actually ignite then extinguish instead immediately, then reignite and work. It does this most times.

Which would mean the flow rate wouldn’t matter, has pressure is fine, the electrics should be fine as it ignites. Andrew even thought it could be a dodgy flue but there are 2 different flues and yet both have the same fault at the same time!

Will be on the phone with Vaillant in the morning and see.

Andrew will pop back as he wants to check the HT lead or something or another as well.

The system layout that he suggests is using the boilers independently, one to do the underfloor and one for the radiators and hot water tank. He wants me to get the accuweather or something on the boilers fitted but it makes the evohome system half redundant so will need to have a think.

 

[chris watkins]

Did Andrew check the termination of the condensates? Both go to the same pipe so if there is a blockage or partial blockage it may cause an intermittent f28 fault code.

Spoke to him today, I think he was going back to check a few things including disconnecting the wastes's.
It makes sense, it could be double trapped or part obstructed.
It has been happening from the start. Would effect both boilers or just the one. Mainly happens around start up just when more condense is produced.
worth a check.
Has anybody pulled the burners to check HeatX and electrodes I wonder ?

 

[Navi Bhander]

Spoke to him today, I think he was going back to check a few things including disconnecting the wastes's.
It makes sense, it could be double trapped or part obstructed.
It has been happening from the start. Would effect both boilers or just the one. Mainly happens around start up just when more condense is produced.
worth a check.
Has anybody pulled the burners to check HeatX and electrodes I wonder ?

It happened a few times June last year and progressively got worse. As we were convinced it was a gas pressure issue and in fairness it did only play up once in a month after the gas pipe was upgraded.

As with all intermittent issues you think it’s cures till it’s not!

Nope the burners have not been touched.

 

[chris watkins]

his was checked by another gas safe engineer before as well. I remember him pouring water down there and stating there definitely was no issue on that side.

Oh well that blows me out of the water. 😕

 

[Navi Bhander]

Oh well that blows me out of the water. 😕

It’s the pipe that comes out of the bottom of each boiler that drips out water?

If that the case I remember the pipes being removed and water being put down the drain pipe that dissappears into the ground and out somewhere to make sure there was no blockage.

 

[Steve weightman]

Seems gas related...maybe dodgy meter governor..just a thought

 

[gmartine]

The system layout that he suggests is using the boilers independently, one to do the underfloor and one for the radiators and hot water tank. He wants me to get the accuweather or something on the boilers fitted but it makes the evohome system half redundant so will need to have a think.

Up to you, I expect his angle is that Evohome doesn't support true weather compensation which'll give the greatest efficiency savings which maybe fairly sizable for a large building. Yes Evohome has plenty of bells and whistles giving you the impression of control but it's really a fairly crude pseudo smart system. Go with the recommendations, if you really dislike the results or lack of controls it can be disconnected and your full Evo reinstated fairly easily I think (Check that with AM).

 

[ShaunCorbs]

tbh i would get the boilers running constant without problems first before you start messing with stats etc

even go down the road of simple controls for now

 

[Navi Bhander]

tbh i would get the boilers running constant without problems first before you start messing with stats etc

even go down the road of simple controls for now

I have been thinking this today.

What I don’t want for do is spend the money on separating the boilers, adding the low loss header, re plumbing everything and then still be left with the fault on the boilers.

I will get the work done asap but want the boilers up and running. What I don’t want is to do this and then find out there’s issues with the boilers, in that respect I’m better off biting the bullet and swapping to one correct spec boiler and save the expense of fitting and redoing the pipework again.

 

[ShaunCorbs]

i would get a llh fitted and the added items to get the system working right then if all else fails this can be still used for a new boiler etc

you sure the new gas main is 63mm seems big

 

[Navi Bhander]

i would get a llh fitted and the added items to get the system working right then if all else fails this can be still used for a new boiler etc

you sure the new gas main is 63mm seems big

63 mm to just under the meter where it reduces to whatever goes into the meter.

 

[Navi Bhander]

Also just a thought here, with my limited knowledge.

If we separated the 2 boilers, one for the underfloor heating so the temperature could be set lower and the other one doing hot water and radiators. As the boilers have CH and HW function on then I wouldn’t really need the LLH? I would just need another boiler wiring centre, and 2 pumps, one for Hw and CH.

 

[ShaunCorbs]

The underfloor heating one wouldn’t like it tbh would cycle like a mother when one or two zones are open

TBH I would keep it as is and sort the pipeing out etc

 

[Navi Bhander]

The underfloor heating one wouldn’t like it tbh would cycle like a mother when one or two zones are open

TBH I would keep it as is and sort the pipeing out etc

At The moment I get 2 boilers firing up for it!

The issue Andrew has by leaving the boilers paired is the hot water cylinder will take longer to heat up as the boilers will only be running at 65’c. Increasing it will make them condense or something or another. I’m an osteopath so a fair bit goes straight over my head!

 

[ShaunCorbs]

I think he means when he separates the boilers as you won’t have 60 kw going to the cylinder only 30kw

Potential with no other load etc

Cylinder will be happy with a flow of 65

 

[Navi Bhander]

Just an update.

With one boiler switched off the other boiler still triggered a F28 code yesterday.

Interestingly I have noted one thing.

It seems to trigger the F28 on the central heating demand for the radiators. As it was a very mild day yesterday the only zone active in the house was our bedroom as it’s set to 20’c as there is a new born in the house.

The evohome system switches the boiler on for 1 min every 10 mins or so to regulate the temp. In reality what happens is the bdr91 relay switches on, the pump switches on but by the time the boiler ignites it only runs for a few seconds before it switches back off as the relay switches off.

Could this scenario some how cause the boiler has supply issue as it’s just ignites and then switches off due to the demand not being required anymore?

I’m mechanically competent and used to restore classic cars. If you start a car but switch it off without it fully turning over it sometimes results in it flooding and difficult to start the next time. In very layman terms could this happen with gas?

 

[ShaunCorbs]

It’s a possibility I would turn that off and make it run for a min of 5 mins before it switches off

 

[Alex Price]

Hi, has anyone tried disconnecting all outside controll interface to the boilers, put the jump cable back in to call for heat and run each one Independently?

I have known a split controll interface spike between the two sides, if the draw on the switch is great enough it can cause some weird resistance values and that can cascade through the pcb, Biasi and morco air pressure switches are good for that. gas supply sounds iffy for the pair but the only constant seems to be the call for heat, Worth a try ?

 

[ShaunCorbs]

Hi, has anyone tried disconnecting all outside controll interface to the boilers, put the jump cable back in to call for heat and run each one Independently?

I have known a split controll interface spike between the two sides, if the draw on the switch is great enough it can cause some weird resistance values and that can cascade through the pcb, Biasi and morco air pressure switches are good for that. gas supply sounds iffy for the pair but the only constant seems to be the call for heat, Worth a try ?

Yep simple controls