Vaillant boiler issues F28 on ecotec 430 not the normal culprit

[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

 

[Abuali]

Not withstanding the F28, it would appear you have a you have 2 oversized boilers on a poorly designed system, I take it from the single large pump that there is no low loss header installed? (60kW through 28mm what were they thinking !!!)

Why haven't you gone back to the installer / manufacturer before now?

When you go down to reset, is it both that show the F28 ??

I agree with you on the Low Loss header installation but regarding the single large pump and the 28 mm pipes what could they have done if the pipe installation was there and it was not possible to amend the pipe work as for example its all within the house without them being able to rip the flooring up and and install smaller pumps for each area/floor.
What would you have done differently?
Thanks in advance

 

[Riley]

I agree with you on the Low Loss header installation but regarding the single large pump and the 28 mm pipes what could they have done if the pipe installation was there and it was not possible to amend the pipe work as for example its all within the house without them being able to rip the flooring up and and install smaller pumps for each area/floor.
What would you have done differently?
Thanks in advance

There’s pretty much always ways. It just needs careful planning and design

 

[Abuali]

There’s pretty much always ways. It just needs careful planning and design

Would very much appreciate your ideas.
I will be very thankful if you can elaborate more on that.

 

[Riley]

Depends on space, where pipes become accessible, is there a basement, can zones be set up differently. Too many variables to give a one size fits all response

 

[Abuali]

Depends on space, where pipes become accessible, is there a basement, can zones be set up differently. Too many variables to give a one size fits all response

I agree its hard to generalise.
But if you are colled to change a two old boilers installed in series to new boilers and all what you see is that the old boilers installed without low loss header.
The new pipe work installation includes you installing a UF heating in the basement floor and with the client dont want to re-pipe the pipe work installation.
Now you left with a boiler room and only u can see two old boilers with two zones valves that you cannot be sure wt areas they control, the pipe work from the boilers room under the street to the house is 35mm run then to 22mm all over the house. (No plans for the old pipework run, most floors are marble tiles!)
A house with 5 floors(incl lower ground flr where the underfloor heating installed on three circuits) each floor area is around 120 sq m with around 25 radiators allover the house and 210l HW cylinder.
What options would you do apart from installting a low loss header and a single large pump .
Any ideas would be highly appreciated

 

[Riley]

Mate it’s too vague. You go there you plan you discuss with the client the benefits of the install you propose and you work together towards a sensible solution. Are you looking for help with an install??

 

[Abuali]

Mate it’s too vague. You go there you plan you discuss with the client the benefits of the install you propose and you work together towards a sensible solution. Are you looking for help with an install??

Not really help but seen something like that in a job by a quite experienced GSR engineer and and as i am new gas safe ☺️ was trying to see what options could be done as honestly I thoroughly searched for ideas couldn’t find a way other than wt the other gas safe engineer done.
But i always think you guys with all that collective experience from other engineers and brain storming would always find away around almost everything.
Much appreciated

 

[Riley]

Need to see the job mate. Do you have a mentor??? College tutor or something?? Did you do a short course

 

[Abuali]

Need to see the job mate. Do you have a mentor??? College tutor or something?? Did you do a short course

It was a year course, I qualified almost 18 months ago but the job i was talking about was new to me. And unfortunately it was few months ago and didn’t took pictures at that time.
For tutors, i know few engineers as i am currently also work with one ( not best wage but am very satisfied am building up my experience) and personally and without offense i do hardly take wg college tutors would say as alot are either “lecture” on theory and books based rules or without all the very fast moving sector.
Experience and examples i see here on this website would need many long years in colleges.

 

[Riley]

That’s kind of the point though mate you do a full apprenticeship so you learn how to size systems and design systems and understand the different ways to make one work. College tutors may not be pushing the most up to date technology but what they will push is solid ground work so that you can sit down with a pencil and paper and correctly size and specify a system. If you have the spec of a larger property then some companies will design it for you. The lectures and books as you call it are the groundwork’s knowledge wise to how to do our job properly. Do you ever make reference to your gas regs when out on the job. You should no one knows it all. It’s the same principle. If you are in anyway not confident with this larger job then turn it down as it will come back and bite you this I guarantee. Also your comment about working round things. Sometimes the customer just needs to be told the correct way to do it and they have to accept it or you need to walk

 

[Abuali]

That’s kind of the point though mate you do a full apprenticeship so you learn how to size systems and design systems and understand the different ways to make one work. College tutors may not be pushing the most up to date technology but what they will push is solid ground work so that you can sit down with a pencil and paper and correctly size and specify a system. If you have the spec of a larger property then some companies will design it for you. The lectures and books as you call it are the groundwork’s knowledge wise to how to do our job properly. Do you ever make reference to your gas regs when out on the job. You should no one knows it all. It’s the same principle. If you are in anyway not confident with this larger job then turn it down as it will come back and bite you this I guarantee. Also your comment about working round things. Sometimes the customer just needs to be told the correct way to do it and they have to accept it or you need to walk

I do totally agree Riley.
I never meant to underestimate the importance of tutors and honestly it did benefit me alot and i still do almost on daily basis after work try read a book or online articles. And strongly believe in the importance of the therotical and scientific aspects of heating systems, just as any other domin.
Regarding this large house as I mentioned before (my mistake if I didn’t clarified it) I didn’t do any work on it, its just i came across it with the engineer i work with and just was trying to “explore” what options could been done more than what he could have done and recommended.

The dilemma I personally find is most of the jobs esp bigger houses most of the times i see engineers have to take over from what had been done, work on old pipe installations so not as easy as new system where you can completely design it from the scratch depending on the therotical and “pen and paper” way. The knowledge and to great extend the experience will definitely decisively help.
Thanks for all your replies and time Riley, very much appreciated.

 

[Chalked]

Edited

 

[gmartine]

@Abuali

Theoretical questions regarding low loss headers (or close-coupled tees)

 

[chris watkins]

College tutors may not be pushing the most up to date technology

Some do, or at least we try.

The dilemma I personally find is most of the jobs esp bigger houses most of the times i see engineers have to take over from what had been done, work on old pipe installations so not as easy as new system where you can completely design it from the scratch depending on the therotical and “pen and paper” way.

It is not so much a dilemma Abuali, it is simple a challenge after all you can only do what you can do with what is in front of you. The knack I guess is to do your best & then set out the limitations as you see them but backing it up with just as much “pen and paper” work as you might on a new project.
For instants take the system & photos posted on this thread.
With only a small amount of research it would be clear that these Vaillant boilers can't work correctly without a minimum flow rate at all times so some form of hydraulic separation should have been created when they were installed. If the existing system only had one 28mm F&R then you would have to set out the limitations of this you could do a flow calculation or in my case check the pipe carrying capacities set out in my "Domestic Heating Design Guide" which shows that a 28mm copper pipe can only provide 40kW at 20deg C drop (at 7C it is only 14 which is what the U/F runs at) so it begs the question why a total boiler load of 60 has been provided?

150sqm downstairs, upstairs is 13 rads and 4 towel rads

Now I am not on site, if I were I could go measure all of the above & work out the heating load (or even do full heat calc's) but as I not I could apply some experience - such as rads tend to average out at around 1.5kW in older houses so around 25.5 for the rads + U/F tend to require around 100 W/M2 so around 15kW's giving a total max heating load of 40.5kW (at -1 or -3 out side temp) so why install 60kW boiler power ??
Do you see how you should be approaching the problems ?

 

[Riley]

Brilliant explanation Chris. No offence meant by the college tutors thing. Mine were brilliant and were very much up to speed, sorry the op seemed to imply his weren’t quite so

 

[chris watkins]

Brilliant explanation Chris. No offence meant by the college tutors thing. Mine were brilliant and were very much up to speed, sorry the op seemed to imply his weren’t quite so

Absolutely no offence taken Riley!! 😎
I know all about the poor levels of knowledge & experience out there in FE land. When you have seen store man or newly qualified Plumbers stuck in front of a class & asked to deliver this very technical subject it is no wonder there are so many poor people out there.
It was just to point out (& as you found) there are still a few of us who try very hard to stay on the cutting edge, mind you what is all this malarkey about controlling a boiler via your hand held telephone....? 😛

 

[Riley]

Well it’s just a gimmick. The whole boiker plus thing is too

 

[pepsidog]

Just done quick pipesize calc and for 8 metres gas pipe, 8 bends and 1 tee on 60kw nett boilers smallest gas pipesize is 35mm. On your picture you show 28mm but then 15mm + couple of bends to boiler . Pressure drop through this would be huge. For these size boilers should be 35mm to as close to gas inlet as possible then 35mm to 22mm reducer then 22mm to 1/2 conex to boiler.
You need gas safe engineer to work out properly. You mention original gas pressure were 16mb. Not sure whether this is at meter or appliance but too low and no gas safe engineer would commission at these pressures as appliance would be classed as “at risk”.
Looking at picture it looks like a diy install, cables all over place.
Best to get Vaillant out to do properly.

 

[Aire]

16mb is not too low and i would commission a boiler at this pressure. All boilers sold in the UK have to work properly at pressures down to 14mb. The only thing you have to maintain is the 1mb drop accross the installation pipe work. And yes his gas pipes are probably undersized but we dont know where his metre is in relation to the boilers so we can't know for sure. he's also getting the same issue when only one boiler is working, in which case the 28mm supply would be adequate.

 

[Abuali]

The only thing you have to maintain is the 1mb drop accross the installation pipe work..

How would you achieve or confirm that 1 mbar drop?

Would you add a test point at the end of pipework just before the boiler isolation valve?

Sorry as i had not seen any engineer install a test point in there, apart from commercial (for tightness testing mainly)

As most of posts in many forums will say the P1 at the gas valve is the test point although gas safe Register Technical Bulletins (tec bulletin 129 published 16 February 2016) acknowledges a possible drop of 0.5-2.5 mbar at the inlet side of the appliance gas control valve.

The Gas supplier must provide a minimum of 19 mbar at the outlet of EcV at peak flow conditions. The pressure drop across primary meter can be up to 4 mbar, leave us with 15 mbar take drop of 1 mbar for pipework then its 14 mbar, and average of 1.5 mbar drop through the appliance pipework and then you end up with a reading of 12.5 mbar at Inlet to boiler gas valve.

I think, and please do correct me if am wrong on this: the key issue in this whether the pressure drop affects the safe operation of the appliance or contibutes to a fault condition then GIUSP should be followed and a Gas rate will confirm a satisfactory operation (GSIUR 26.9(c)) Esp with the zero govenor or Air/gas ratio valves where burner pressure measurement is not appropriate

 

[Riley]

The maths will tell you if your pipework to appliance is below 1mbar drop. What the appliance will work at is inconsequential as this prerequisite must be met in the first instance.

 

[Harvest Fields]

Why are we still talking about this in an open forum? I thought the OP had an engineer that was sorting him out?

 

[Riley]

Yes it has strayed rather

 

[gmartine]

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?

How are you getting on, anything to update?