Valliant Eco tec plus 637 Fault F75

[move2leeds]

I had a Eco Tec 637 fitted 18 months ago, was fitted by uncle whos corgi registered, it's been serviced. He recommended a TOTAL new system to the house, so all pipe work was removed new installed. ( He lives in Ipswitch I live in Yorkshire, but hes currently away hence me writing here!)

A week ago I bleed the radiators re-pressured the system to 1.5 when the system was off and cold, everything fine. 2 days later I heard an almighty banging from the boiler like someone was hitting it with a hammer, and the pressure needle jumping all over the place. Turned it off left for 5 mins restarted the boiler, and everything seemed to return to normal. I noticed the room get cold and when i felt rads they were off. Went to check on boiler and saw F75. tried several attempts to get it back on. In the end the only way I could get heating, was to lower the pressure by taking water form a rad, turning the boiler back on and then pressure up when it was trying to kick in. that got it working.... next day I called Valliant to come out , the same day same problem with banging, Had the problem all weekend, Valliant couldnt get an engineer out for 4 days....froze then warmed froze then warmed.
Engineer has just been today tested the water said it was black ( which it was, im not going to deny) said it was that that was the problem, it had effected the heating exchange, said said they wouldnt touch it untill I'd had a power Flush and inhibitor put in as it will invalidate my warrenty, If after I had this carried out and if the problem still persited they would then come back, test the water even if it was clear, which takes a week and then change the exchange........

DOES this sound plausible???? and if so, I have still got the problem untill a power flush, Engineer said press ignition button and it will relite but it DOSENT!!! and I dont want to keep emptying and repressuring to get heat as that i know doesnt help a system but its freezing! How much will I be looking for a power flush, the house is 4 floors, with 13 rads and a Mega flow 210 tank thanks

 

[Agile]

Its essential when a new boiler is fitted that the system is properly cleaned and thats usually by power flushing.

I always get this feeling that a relative will not want to charge the usual amount and then will do a poor job because he is charging less.

In the normal course of events you would call back the installer and get him to power flush it all free as he should have done it properly in the beginning !

Now you are in a fix!

Power flushing a large house like that would usually be about £450.

Tony

 

[gas4you]

F75 is a well known and documented fault with Ecotec boilers.

It can be made worse with dirty system water, but more often than not it is a faulty pressure sensor.

Call Vaillant out under warranty. You still have 6 months left yet

 

[Deleted member 105431]

F75 is a well known and documented fault with Ecotec boilers.

It can be made worse with dirty system water, but more often than not it is a faulty pressure sensor.

Call Vaillant out under warranty. You still have 6 months left yet

f75 is a faulty pump (jammed) or pressure sensor. If the system is full of sludge this will cause the pump/sensor to fail prematurely. If you have a pink coloured pressure sensor it may be faulty but it sounds like you have a dirty system (and a very oversized boiler!) I would range rate the boiler down to 26kw and check for an external autobypass.

 

[ollski]

Is this one of the ones with the stupid rubber hoses from the hx, if it is expect that to be the problem.

I've really gone off vaillant had a turbomax with a faulty honeywell gas valve lead, took out the gas valve and pcb with it...over 2 days I have been on hold to vaillant tech for 4 hours!!, had to work it out myself in the end after all that!

 

[Deleted member 105431]

Is this one of the ones with the stupid rubber hoses from the hx, if it is expect that to be the problem.

I've really gone off vaillant had a turbomax with a faulty honeywell gas valve lead, took out the gas valve and pcb with it...over 2 days I have been on hold to vaillant tech for 4 hours!!, had to work it out myself in the end after all that!

that is a very easy fault to diagnose and is very well documented/known amongst Vaillant engineers.

 

[ollski]

that is a very easy fault to diagnose and is very well documented/known amongst Vaillant engineers.

Shame they can't be arsed to share it or even answer the phone.
Agreed it is very simple to diagnose the fault initially but most of us with no prior knowledge wouldn't really be expecting to look for a boiler so badly designed that a simple fault takes out 2 other major components.

 

[Agile]

Shame they can't be a***d to share it or even answer the phone.

I have a feeling that the book does not even mention that there is a diode bridge in the gas valve lead!

Easy enough to discover if you measure the resistance of the lead though.

Tony

 

[Deleted member 105431]

Shame they can't be a***d to share it or even answer the phone.

Easy enough to discover if you measure the resistance of the lead though.
Tony

a 30 second test with a multimeter is all it takes. But then I wouldn't expect you ever use a multimeter (or know how it works) being BG ollski.

 

[ollski]

Lol, I certainly dont have mutilated probes that can get into the connections in the lead if that is what you mean, but I do have the bulletin from vaillant saying the lead itself can't be tested, merely polarity and resistance checks on the valve and board.

 

[Agile]

The lead can be tested, but not with just a multimeter. It needs an AC source of say 12 vac and a load of say 56 ohms and then measure the voltage across the load.

Amusingly the BG would test the lead for continuity, find there is none and then assume its faulty and replace it.

I have not encountered enough failed leads, but they probably go partly short circuit and it may well be possible to measure a failed one on a multimeter. Pity the PCB designers dont put some protection on it.

Tony

 

[Deleted member 105431]

The lead can be tested, but not with just a multimeter. It needs an AC source of say 12 vac and a load of say 56 ohms and then measure the voltage across the load.

Amusingly the BG would test the lead for continuity, find there is none and then assume its faulty and replace it.

I have not encountered enough failed leads, but they probably go partly short circuit and it may well be possible to measure a failed one on a multimeter. Pity the PCB designers dont put some protection on it.

Tony

It is a well known but rare fault. I work on these boilers on a daily/weekly basis and find one such circumstance a year approximately.

 

[Agile]

A lady who I know a little socially, undercut my very reasonable boiler replacement quote and had a Potty fitted by a non registered Portugese plumber ( who had the cheek to call and ask my advice on boiler models ).

The diode bridge lead failed during the first week and Potty had so much trouble with them failing that they had run out of spare ones.

She asked me for help but, although I would have got it going had I fitted the boiler myself, all I did was to give her the email of the potty spares director. She is a very tenacious woman and unfortunately she found that BG has just one left in their spares store. I was disappointed to hear that!

Tony

 

[Deleted member 105431]

A lady who I know a little socially, undercut my very reasonable boiler replacement quote and had a Potty fitted by a non registered Portugese plumber ( who had the cheek to call and ask my advice on boiler models ).

The diode bridge lead failed during the first week and Potty had so much trouble with them failing that they had run out of spare ones.

She asked me for help but, although I would have got it going had I fitted the boiler myself, all I did was to give her the email of the potty spares director. She is a very tenacious woman and unfortunately she found that BG has just one left in their spares store. I was disappointed to hear that!

Tony

What a cheek! I'd have told her (and the portugese bloke) to poke it!

 

[move2leeds]

The System was completly new, as the house was a shed when we bought so all new pipe work rads etc.....as there was nothing here! but was still flushed with Senitol X500 and Senitol Inibitor X100 2 bottles added.
With regards to the comments about the system been too large the house is a victorian detached 5 bed, 2 bath ( 3 kids!) and 3 large downstairs rooms, kitchen and 3 cellar house!! which is to be extended ( god it sounds as if im in buckingham palace!) to add a large dining kitchen down stairs bathroom and 2 ensuites and 2 loft beds, so the the system was added knowing this work is to be carried out . So thats why the system was put in.


ANYWAY>>>>>>>> I called Valliant back out after reading other plumbers comments spoke with my uncle as he landed! and demanded a 2nd opinion, they came today, took a water sample .............which was clear!, and the engineer this time said he could smell the inibitor in the water, and he knew that it was ok, said immediatley it was the pump, took the pump out where there was a slight build up of Ferrous iron, checked the balancing etc.... and suggested investing in a MagnaClean. Checked the sensor, air etc... all ok, we turned the room termostat and boiler on and BINGO fired straight up, rads boiling hot and hes been gone 4 hours and were still running, I was lucky if I got 20 mins of luke warm radiators, before the F75 Code came and locked it out for the last week.

He says whilst he wont slag other engineer off..... he did say he knew him, and that he should of let the water run for more than 1 second not take from the pressure realease valve, checked the rads water, which was clear.....and said "maybe he needed to leave work early!" and smiled!
So I'm all up and running..............lesson don't trust them........and ask for a second opinion .............and get your Uncle to move closer to you!!