Vaillant boiler issues F28 on ecotec 430 not the normal culprit

[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

 

[Antonio Dinis]

Hi there
See if this helps

 

[Antonio Dinis]

By the way I’m a gas engineer

 

[Antonio Dinis]

Pure or plus are the same on this case

 

[gmartine]

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.

As tempting as it is (because you can) trim down demand to the odd radiator. Unless you have a boiler that can modulate 20:1 or so your boiler is not going to like it one bit so open up a few zones/rads even though it seems counter intuitive.

 

[Riley]

By the way I’m a gas engineer

Then please pm your details to @Riley @ShaunCorbs or @Harvest Fields and we can arrange for you to gain your gsr tag and access to gas safe only area. Until you have it then please be wary on commenting on gas issues as our members need to know that we talk gas safety very seriously. Keep posting, introduce yourself hang around. Very nice to have you