Vaillant ecotech plus 831

[ajcon]

Hi,

My boiler is making a lot of funny noises and is not working. The pressure seems fine but it is not firing up. The display gave me an error message one time of ‘F20’ with an ignition symbol to the left of it. Is this a gas supply issue as my pressure at the boiler is only around 14.5/15 and not the required 17.5? Any advice greatly appreciated. It is just over 12 months old. Cheers

 

[kevindgas]

how are you determining gas pressure? as you should have 20 at the inlet of the boiler!

 

[kevindgas]

F20 is an safety temperature limiter by NTC activated fault

and is linked to Flow NTC not connected or faulty

to get a list of last ten faults press i & - together then scroll up or down

 

[ajcon]

Thanks for getting back Kevindgas. I think with Vaillants it is 17.5 at the inlet from previous posts when I asked this question. It looks as if it was never installed correctly – I think there are issues with my gas carcass underneath my floors which unfortunately are wooden floorbloods. Faults are - two F20s and the rest F75s. What needs to be done based on these errors and to get the boiler back working again asap. I am prepared to cut into part of the floor and replace say the 1st 5/6 feet of the run from the gas coming into the flat (which is a 2 bed ground floor – 1 other above) with larger piping hoping that this will bring the pressure to within the required level – maybe also at the other end where it meets the boiler. Will this make a difference do u think? Apologies if I go quiet but I’m popping out but will log on again later. Your input is greatly appreciated – Thanks . Andy

 

[ajcon]

Sorry NTC ? I’m a real novice fella

 

[ajcon]

Hello again, Any feedback re what fault F75 is. These were shown after 2 F20 faults. I am unsure how old they are as the pressure was low on it months ago and it showed some faults. I was advised to top up by opening 2 screws underneath the body of the unit which I did and the pressure topped up. It’s been working fine until recently. In simple language what do these errors mean and what do I need to do to rectify the situation as quickly as poss. Last thing I want is to get someone around and get ripped off again with work that doesn’t need doing etc . Many thanks for your help in advance.

 

[kevindgas]

sorry have been out this afternoon as one of our horses has a new foal and we have had trouble with a new foal before with this mare so we are keeping an eye on it.

anyway F75 is a flow detection fault

No pressure rise was detected on turning on the pump
-- water pressure sensor or/& pump defective
-- quick bleeder not removing air (located on back top of pump)
-- too little water in appliance

ntc is the Vaillant name for a temerature sensor/thermistor

so i would be looking at a blockage or sticking pump, air trapped in pump or crud in the system water.

I doubt gas pressure is the problem in this case, but should be 20mbar at the appliance but most Vaillants will work at anything as low as 14mbar

 

[ajcon]

Thanks for getting back. I hope all turns out well with the foul. I just tried to turn it on again to see if we could get any hot water for a bath and after making weird noises cam up with the F75 again. I had a Magnaclean installed which is attached to a pipe – I haven’t cleaned this out or anything in the last year since it was installed. Should I try and turn up the water pressure via turning the screws on the bottom again and see if that makes a difference and makes it fire up? It is resting at present at just above 9 o’clock. When it was fitted a year ago it was chemically flushed/ cleaned and the debris wasn’t that dirty I believe (unless it wasn’t done correctly). Fault 75 sounds pretty ugly? Is it going to cost a lot to get mended? Thanks again. A

 

[ajcon]

sorry foal - typo there.....

 

[glasgowgas]

you said that the pressure was fine, but could you tell me what the system pressure is when cold.
you should clean out your magna clean as often as you think ( every 3 months) the dirtier this gets the less efficient your system will be.

make sure boiler is properly vented, an airy heat exchanger will heat up far too quickly for what the ntc thermistors are looking for

 

[ajcon]

I topped the pressure up a little and turned it on and there was nothing. I turned on the hot tap in the bathroom full, turned it on and off again and it tried to fire up but it went into F20. When cold, I assume u mean is when not in use. I am looking at the little gauge and it sits at about 9 (although now at 10 after my top up). When the rads were on etc it went to about 11. Re the ventilation, it’s on a side wall of the flat and there is a flu going out and a pipe leading to the drain. There are holes from piping in the wall from the previous boiler that haven’t been filled in which would let in a lot of air I amagine. Is this what u mean by airy?

 

[ajcon]

sorry – 2 other things that might be worth mentioning. Since the new boiler has been fitted I have been getting a lot of pipework squeaking that I didn’t previously have. When taps are turned on or the heating goes on and off I get a lot of pipework noise. The boiler over the last couple of months has also been turning itself on and off for a few mins every so often – quite regular – it fires up and then stops – no rads are heated in the process though. Could this be linked to the heat exchanger? Cheers again

 

[kevindgas]

. Re the ventilation, it’s on a side wall of the flat and there is a flu going out and a pipe leading to the drain. There are holes from piping in the wall from the previous boiler that haven’t been filled in which would let in a lot of air I amagine. Is this what u mean by airy?

err no!!

what we are saying is air in the pipes/pump/heat exchanger stopping circulation

have you checked on the pump's auto air vent that the cap is open?

 

[gas4you]

F75 is a classic and very common Vaillant fault, although they will not openly admit it It will be either a faulty pressure sensor (85% of the time) or crap in the system that has blocked the pressure sensor.

The pcb looks for a 0.2 Bar pressure increase once the pump has started to prove the pump is working.

 

[glasgowgas]

kevindgas & gas4you,looks like this thread could run and run!!!!!!!!

to the OP what is the pressure in your boiler. it should be between 1 and 1.5 bar.

if you do not have the correct amount of water in your boiler and system then you could have air in your boiler/ heat ex/pump,so when the boiler fires it is heating air not water.

was your old system thoroughly cleansed?
did you clean out magnaclean?