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Vaillant Boiler F.75 error code...


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Old 14-02-2010, 17:26
undermytree
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Anyone know what I should do? What does that code even mean!? This has appeared on our boiler display. No heat or hot water. The boiler is still under warrenty but is there anything I can do (DIY) NOW to fix the problem...Just what you need at the weekend... Is it a call to the engineer in the morning and 's?Hope its covered under the warrenty and its only tonight we have to suffer the inconvienence!

Any background info , that will make me sound like I know what I'm talking about tomorrow, when I call it in, much appreciated
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Old 14-02-2010, 17:40
CaptMcMallister
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Anyone know what I should do? What does that code even mean!? This has appeared on our boiler display. No heat or hot water. The boiler is still under warrenty but is there anything I can do (DIY) NOW to fix the problem...Just what you need at the weekend... Is it a call to the engineer in the morning and 's?
F75 is the pcb not acknowledging the pumping kicking in from the sensor measuring the change in pressure.

Most likely cured by changing the sensor, its a known issue with the Ecotec plus range (I assume that's what you have as you haven't told us).
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Old 14-02-2010, 17:44
undermytree
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Its an ecotech pro 28...feeling very ill informed here...
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Old 14-02-2010, 17:48
undermytree
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F75 is the pcb not acknowledging the pumping kicking in from the sensor measuring the change in pressure.

Most likely cured by changing the sensor, its a known issue with the Ecotec plus range (I assume that's what you have as you haven't told us).
Its an Ecotec pro 28 .. Sorry, I am rubbish with this sort of thing!

(And the thread seems to be sticking too, just to make my day !)
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Old 14-02-2010, 17:53
undermytree
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F75 is the pcb not acknowledging the pumping kicking in from the sensor measuring the change in pressure.

Most likely cured by changing the sensor, its a known issue with the Ecotec plus range (I assume that's what you have as you haven't told us).
Thanks for the response Captain! I have no shame...what does 'pcb ' mean?
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Old 14-02-2010, 17:55
collincn
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printed circuit board - the contol system
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Old 14-02-2010, 18:04
undermytree
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Thank you!
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Old 14-02-2010, 18:35
Andykel
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As above. Likely the sensor, also worth checking is the pump and water pressure in the system.

Regardless, it's under warranty - give Vaillant a call.
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Old 14-02-2010, 18:46
seacam
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Hello Under,

F75.

My money first is on a stuck pump or a defective one, very common across the range,--- then the sensor.

Before new boiler was hung, did you have the system throughly flushed, if not you had better get use to F75s, that or have the system throughly flushed?

Also check bypass valve and believe it or not, the expansion vessel.
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Old 14-02-2010, 18:50
Andykel
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, the expansion vessel.
Ah yes. I forgot that one! Fooled me a couple of times in the past also.
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Old 18-02-2010, 22:18
Tynan
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Hello gents

same here, a 2 and a half year old Ecotec pro, been good as gold until a month ago and since then the pressure falls to shutdown levels over about three days so Ive got rather used to topping it back up via the filling loop, finding a leak seems to be impossible from what I've read

anyhow, for the last three days it's starting gving f75, it tries to start, funny whirring scarpy noise that fits well with a stuck pump, I've read about the sensor too

anyhow, is this tackable for a dumb grunt with simple tools?

are the pump and sensor easily accessable and removeable and cleanable?

I'm brave but not stupid ...
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Old 18-02-2010, 22:34
Andykel
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As your pressure is dropping on a daily basis it sounds like your expansion vessel has lost its air charge. Find out where your boilers blow off pipe exits the property and place a bowl/bucket etc underneath it and leave for a day or two with the boiler operating (and repressurise it if needed). If the bucket fills from the blow off pipe your expansion vessel needs pumped up. Expansion vessel problems can also cause an f75 code.

The scrapy noise you're hearing could just be a pump attempting to circulate with no water present in the system due to it all being vented outside because of the vessel issue.

If memory serves the ecotec has it's expansion vessel within the combustion chamber. If you remove the casing and gain access to the vessel, drain off the boiler via the blow off valve (a quick turn to the side), attach a foot pump to the shraeder valve of the vessel and charge to approx 1bar (don't look at the boiler gauge, check the gauge on your foot pump).

If in doubt call an engineer out.
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Old 18-02-2010, 23:04
seacam
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As your pressure is dropping on a daily basis it sounds like your expansion vessel has lost its air charge. Find out where your boilers blow off pipe exits the property and place a bowl/bucket etc underneath it and leave for a day or two with the boiler operating (and repressurise it if needed). If the bucket fills from the blow off pipe your expansion vessel needs pumped up. Expansion vessel problems can also cause an f75 code.

The scrapy noise you're hearing could just be a pump attempting to circulate with no water present in the system due to it all being vented outside because of the vessel issue.

If memory serves the ecotec has it's expansion vessel within the combustion chamber. If you remove the casing and gain access to the vessel, drain off the boiler via the blow off valve (a quick turn to the side), attach a foot pump to the shraeder valve of the vessel and charge to approx 1bar (don't look at the boiler gauge, check the gauge on your foot pump).

If in doubt call an engineer out.
Yep I agree but the pump is a known problem but checking/charging the vessel is the cheaper first option.

Also Andy, the F75 error code mimics what is in fact and F22 code/cause on the Ecotecs, ( so I have found ).
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Old 18-02-2010, 23:08
seacam
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Hello gents

same here, a 2 and a half year old Ecotec pro, been good as gold until a month ago and since then the pressure falls to shutdown levels over about three days so Ive got rather used to topping it back up via the filling loop, finding a leak seems to be impossible from what I've read

anyhow, for the last three days it's starting gving f75, it tries to start, funny whirring scarpy noise that fits well with a stuck pump, I've read about the sensor too

anyhow, is this tackable for a dumb grunt with simple tools?

are the pump and sensor easily accessable and removeable and cleanable?

I'm brave but not stupid ...
Hello Tynan,

I saw your other post, Andy's advise is good so follow that, although we differ on cause but if the pump is running on dry, what ever the cause it's going to make a noise.
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Old 18-02-2010, 23:27
Tynan
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thank-you very much indeed

suspect my post wasn't clear, apologies

the pressure dropping is one thing, thatt akes place over about three days gradually, started about a month ago

more pressing is the f75 error, that's two days ago, the heating runs all night on a low setting, the house is warm when I wake up, I'm guessing that it shutdown at 6am when it's set to kick up to the higher temperature? that's happened the last two mornings

a squirt of extra water through the filling loop fixes it so far

but today it failed at about 8pm, again a quick squirt of water through the filling loop and it restarts perfectly

the pressure guage shows pressure to be fine when the f75 shutdow happens

be assured that I stop as soon as I get frightened

I'lll check the outdoors stuff tomorrow
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Old 18-02-2010, 23:50
seacam
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thank-you very much indeed

suspect my post wasn't clear, apologies

the pressure dropping is one thing, thatt akes place over about three days gradually, started about a month ago

more pressing is the f75 error, that's two days ago, the heating runs all night on a low setting, the house is warm when I wake up, I'm guessing that it shutdown at 6am when it's set to kick up to the higher temperature? that's happened the last two mornings

a squirt of extra water through the filling loop fixes it so far

but today it failed at about 8pm, again a quick squirt of water through the filling loop and it restarts perfectly

the pressure guage shows pressure to be fine when the f75 shutdow happens

be assured that I stop as soon as I get frightened

I'lll check the outdoors stuff tomorrow
Hello Tynan,

Pump and a leak or expansion vessel, but check vessel first.
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Old 19-02-2010, 10:18
Tynan
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Ta

Right, the 'blow off pipe'. That's the plastic pipe that goes out and then runs down to the drain? About 20mm ish, other than that i have the one the steam/gas comes out of and a small metal pipe poking out that I'm almost certain is left over from the old boiler. bucket bag on that for 24 hours, fine

and take the cover off and attach a pump to the car type valve I should see on top and pump to 1 bar

is there no way to check the expansion vessel air pressure from the control panel?

and if the little dial on the bootom right side shows me I have pressure than I do surely? I do;t follow the suggestion that the boiler/pimp is dry

Thanks again, I have an engineer booked for Monday but I'd be ever so pleased not to have to pay out if it can be avoided

I'm up bright and early on Saturday to try out the suggestions
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Old 19-02-2010, 11:06
nightstar
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I'm glad I found this thread - I have the same boiler with the same ongoing problem.

Thanks.
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Old 19-02-2010, 11:10
Tynan
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Hi nightstar, lets make a pact that the person that fixes their boiler first has to come round and do the same for the other person

do post progress here please, 'll be tackling mine Sat morning with perhaps some preparatory reconnaissance this evening

I might take the day on Monday should the engineer be needed so I can learn something for the future
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Old 19-02-2010, 23:23
Tynan
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hmm. Friday night reconoitre

well, got the cover off fine and seen the valve for the expansion vessel

seen finally the PRV tappy thing at the back RHS under the case, not inside the bloody case at all

so I've resisted tacking it at 11pm on a Friday night, wil do tomorrow, so as simple as dump the water through that PRV, pump the expansion vessel up to 1 bar, close PRV, filling loop to get water back in and then turn back on?

also, the bottom od the boiler case looks like some thing has leaked and dried to a fine brown residue like plaster, is that just the byproduct of the installation or evidence of a/the leak? a couple of the lowest pipes has a fair bit of residue caked on

I took a picture of the bootom of the case, some bloody big and bloody dry moths in there, will try and post it shortly

once it's drained how hard is it to remove and clean the pressure sensor (it is the dodgy pink topped one) and the pump? full and detailed instructions with liberal warning tips would be appreciated
thank-you
Tynan
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Old 19-02-2010, 23:56
Tynan
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http://www.tynandean.co.uk/IMG00013.jpg

http://www.tynandean.co.uk/IMG00110.jpg
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Old 20-02-2010, 07:44
Tynan
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mornnig

when I put the case back on the boiler last night and turned it on, it did the thing, tried to restart, make a noises like something did;t want to and then f75, a tiny squirt of warter from the filling loopand it started perfect, I'm getting so good at making the squirt tiny it keeps the pressure in the gray, top of anyway

it's run all night and the pressure has barely dropped at all that I can see

just put a bucket under the outflow pipe and there's a slow steady drip, perhaps a drip every six to ten seconds, any water there is a bad thing isn't it? over three days that's be significant I assume

ah well, showers etc for the mob and then I'm going to drain through the PRV and pump the expansion vessel to 1 bar, fingers crossed
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Old 20-02-2010, 09:17
fat controller
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These links are asking for some kind of username and password?
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Old 20-02-2010, 10:25
Tynan
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ah, sorry

ah well, I now know that what i thought was the blow off pipe ws the condensate pipe, that drips every five seconds but I think that's ok yeah?

the little meatl on I thought a relic is indeed the blow off pipe, almost certain that oe os dry as a bone although it took a while jiggling the PRV to get it to stop dripping

umm, released the pressure i the boiler and pumped the expansion vessel up to 1 bar from about 3/4

frankly honour is stisfied now and I'll let the engineer take over on Monday, that;s if it gives any trouble n the mean time, it's too bloody cold to have it off while I tinker doubtfully

thanks t all for their help, I know at least something about the boiler now

right off to watch West Ham massacre Hull by way of cafe and pub
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Old 20-02-2010, 10:59
seacam
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Pacts, I think a better understanding wouldn't go amiss.

Hello, Under, Tynan, Nightstar.

Tynan, is there any point in asking you to stop what you are doing to your boiler and just read a little, I ask cos' you may cause yourself some major problems and you might just save your self some time and work in the long run.

That thing sticking out of the wall creating steam is the flu and the steam,---that's exhaust gases.

That 20mm pipe is your condensate drain, it should be a larger pipe and it should be lagged.

That bit of pipe sticking out of the wall is not a left over from the old boiler but is in fact rather important on the new one,----is your PRV pipe.

As explained the F75 is indicative, ( and is usually correct ), of a failed sensor or faulty pump, ( knackered or sticky ).

As explained the F75 error code can mimic another fault code, F22 as I recall, ( but this is a rare occurrence and I've not seen it reported elsewhere ).

Early in this thread I mentioned a faulty or discharged expansion vessel would also give a F75 error code.

Since then this thread has have moved away from sensor and pump to the culprit being definitely the EV,------not so.

It is well known that the pump and sensor across the ecotec range can be iffy.

6 out of every 10 faults on these units,---- it will be the pump or sensor reason for the F75 code.

However a faulty or discharged EV may produce the same EC, this is my experience.

However in this thread, leaks have also been written about.

Generally the usual culprits and rightly so of a leaking system is a a rad' nipple not done up, pipe work & joints, pinhole rad', leaking rad' valves,----- you get the picture.

The above are the usall reasons why a system needs constant topping u as well as a faulty PRV.

If a faulty PRV you will see drips or pour from the PRV pipe out side.

The PRV can also be activated if you leave a filling loop in place, connected both ends, SO DONT DO THIS.

How ever there is a more serious reason for a leak in a CH system, I'll write more of that later.

The easiest thing to check, ( although most times not the culprit ) is the EV,---- if showing an F75.

An F75 code is unlikely to tell you if the EV is knackered but a simple check can.

With the system off and the housing/case,---- find the Schrader valve, ( looks like a tyre valve ), depress the centre pin, if water shoots out, STOP, you need a new EV,-----period.

In all the posts/problems mentioned in this thread this is a highly unlikely event.

Next check to undertake is if the EV needs charging,----- follow Andy's post 12 for this.

But I will add to his advise and explain further maintenance work, important maintenance should be undertaken at the same time as the re-charge or a pump change, which will make an easy task a little more harder and take longer, more expensive but well worth it.

Referring back to the other cause of leaks mentioned earlier, not often mentioned is system erosion gas, this too can cause a system,--- lead to leaks or constant topping up in a CH system.

What has that to do with re-charging?,----well prevention for one thing.

Anyone who knows of me on DS may have figured I'm on a mission to get everyone with, old, new, just about to replace,------to chemically pre-clean or simply clean their system and then introduce inhibitor in their systems but especially so before strapping a new boiler to the wall and to an existing system.

What is not mentioned a lot is that a gunged up, internal dirty system can result in leaks and can make your combi/boiler loose pressure.

To change a pump or recharge the EV because of the above EC you are going to have to isolate and drain the combi so might consider the works below.

If you can live with the hassle of slow leaks or constant topping my advise would be three weeks prior to any maintenance, drain a rad', introduce via the bleed nipple X400, allow it to do its work then do your maintenance.

If on the other hand you don't do the 3 week introductory thing but crack on for the reasons above my advise would be to drain the whole system, not just isolate/drain the boiler, do any maintenance then introduce X 400, leave for three weeks, drain/flush, introduce inhibitor, pressurise system.

You have to isolate/drain the boiler/combi or the whole of system before you re-charge and EV,----your pressure gauge should read 0.

If your EV is reading 0.8 to 1 bar the EV, the charge is fine, [b] don't charge. [B/]

If you leave your filling loop connected you may activate your PRV if the combi is being over pressurised.

Below advise goes for all combis and boilers but more so on some brands and models then others.

Two of them being Valiant and Vokera, they really don't like dirty systems, especially the ecotec range.

If you are finding water marks in side a casing that is indicative of a small leak but a lot of these drips self seal but it can also mean a perished/worn washer or leaky joint and these needs to be dealt with before the PCB is ruined and until these are done the boiler/combi will require constant topping up.

I wouldn't be surprised to be told,-----but would be to find in this thread,------ if any of the EVs needed charging.

IMO the F75 EC is either the sensor or pump,-------then the EV.

While not required to fix a F75 EC If any of you lot had your Vailliant strapped to a wall,---to an existing system, I really do recommend a chemical clean and flush.

But I'll think you will find it's the sensor or pump for your F75EC.

( note to self seacam, confusion reigns when you throw a little extra knowledge into the mix ).
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