Vaillant EcoTEC Combi Boiler - pressure / water issue ?

[hedgedge]

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• hedgedge
• 26 Dec 2014
• 1

Thanks again gazdaz36 and bunnyman, I think you're both right. Before I swop hot and cold pipes around can someone confirm from the picture attached that the cold IN should be the plain copper pipe to the left of the central chrome gas pipe (not as the order in the label) and that the hot OUT should be the one with the currently closed grey valve (again not as the order indicated by the label). The system is currently plumbed the other way around - as in the order shown on the label. I can see why the pressure may drop with a hot water tap left when the cold IN is switched off. Apologies for random capitalised 'chance' word in last post. Please ignore that one word. Otherwise I hope all else makes sense and the image does not appear back to front. It's not how things appear to me when lying on my back in the loft space but as a camera phone recreates, as if taken looking up at the boiler as if hung high on a wall - viewed from below the boiler facing the wall on which its hung...

 

[hedgedge]

Actually forget all that viewed from business. I'm not making sense but I'm sure you'll figure it out. My theory is that someone put the label on the wrong way round??

 

[hedgedge]

Just checked official installation documentation and the label is right and the boiler is plumbed the right (page 20 of http://www.vaillant.co.uk/mediaarchive/2013/10/ecoTEC-installation-servicing-2-2005.pdf). Perhaps I've just opened the valve that needs to be closed and closed the one that should be open?!? Any other ideas, please let me know - if I don't get back in half hour with good news.

 

[The831Bunny]

The connection to the NRV (non return valve) and the cold inlet tap are reversed. Shut the grey tap on the heating flow (far left 22mm valve) and that will go some way to retain your system pressure.

What's happening is your heating (radiator) water is passing back through the cold tap (NRV not in correct place) and draining out through your shower/hot taps when you use them. I bet you are having orange tinted hot water too... This drops the system pressure till it faults on F.22/F.75. You turn off the hot water, it refills because the taps are open, and off you go again after you reset the F.75 or it repressurises.

Your cold main must be under 2 Bar static pressure too, as otherwise there would be quite a gush from the boiler safety valve. I'd get the firm back to attend to that pronto. It's breaking water by-laws for a start...

Edit added: that NRV is probably shot too as in its position it is in now, it shouldn't let ANY water into the boiler, unless the hot and cold are reversed too lol! Run the hot tap and feel which one gets hot...

 

[hedgedge]

Hi 831 Bunny, I'm just down from the loft space after fiddling around with those grey knobs. I've managed to get things working by turning the grey knob where the cold comes in, to part way. Sounds odd but with it fully open, nothing comes out of the hot taps. When it's part open (and with the other closed to maintain the rad pressure) all works fine. Do I have a broken NRV and does it matter??

 

[The831Bunny]

You need to get it repiped correctly.

Only educated guesses with a spattering of experience otherwise from this end.

If the bloke can pipe it up like that, then the plastic tap handles could have been put on with the wrong orientation too... Who knows sorry to say...

 

[Bunnyman]

As 831 said u got the mains comin in where the non return valve should be, the bloke wants a kick up the bum... Just plumb it right...
There's nought wrong with the boiler, just the installs wrong, but it needs fixing urgently or u will cook the boiler up

 

[hedgedge]

Thanks for replies. I woke this morning to a cold house . Checked boiler, and even with the filler tap fully closed (on left as looking from front), the pressure had crept up to 3.0 bar shutting the boiler off - error 75. No problem as I'm plenty familiar with how to get the pressure down. It's been going all day today after dropping pressure to 1.0 although I've not gone up to see if pressure is creeping up again as it probably will be. As earlier I have the other tap at 45 degrees. It stops the flow if its in the on or off position. This one being the mains cold water coming into the boiler. The 'plumber' that reconnected the boiler is long gone on other jobs in another part of the country. Bunnyman, please can you confirm what you mean when you say that the cold water should be connect to the non return valve. It looks to me that it is connected as described in the installation docs - see page 20 of link to vaillant website PDF earlier in thread - though you probably know how things should look etc. If I can survive until he returns I will but I know enough to put things right myself if otherwise. Thanks again for help.

 

[bedfordkeys]

every house ive lived in ive had trouble with the boiler.this time moved in 6 years ago searched for best bolier and came up with the ecotec plus831.luckily i took out insurance after first year with npower and nearly every year ive had to call them out to fix it. ive just been up in the loft to raise the pressure bar down to zero tomorrow i will be phoning npower. my advice is to get insurance

 

[The831Bunny]

Any boiler is only as good as the engineer who installs and 'services' it...

 

[hedgedge]

Ok thanks guys. Will get insurance next time. Meanwhile it works like this (see pic) for about 8 hours. Then the pressure rises too far and I have to open the tap that is used for topping up the rads and close the 'mains in' tap (see earlier pic). With any hot tap on, this reduces the pressure and it fires up again after a reset. Then it's back to the funny 'half way setting' for the 'mains in' Tap. Any ideas please let me know and I'll pipe it differently or replace nrv. Thanks

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• hedgedge
• 29 Dec 2014
• 1

 

[stardanny]

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• hedgedge
• 26 Dec 2014
• 1

The main cold water and flexible filling hose is wrong way. The silver flexible filling hose should be connect to NRV and the incoming water main should be connect to where the flexible filling hose used to connect.

Can you see the brass little slot next to grey knob on the left? This is the isolating valve for water main. This is where the water main pipe go to.

With this turn on to get hot water, with the grey knob on, while the heating is repressured, the hot water will not come out.

I am surprised the circle clip holding NRV is holding well under pressure.

After it refit the correct way, Make sure the grey knob on both left and right is closed 100% shut after repressure heating, remove circle clip between left grey knob and NRV, pull the NRV out and into a small bowl, open the right greys knob, if water come out of NRV, it is faulty. If no water come out, NRV is fine and refit back, refit clip and turn right grey knob closed.

Daniel.

 

[hedgedge]

Thanks! I'll have a go. Family getting wound up so if I can't sort easily I be back for phone numbers. Anyone local to Brighton?

 

[Bunnyman]

For gods sake mate u got 2 blokes with 60 years vaillant only experience between them! Stop asking the same questions! We told u what waswrong u keep questioning an banging on.. Either fix it or get someone to fix it.. It may be to late now with the damage done

 

[hedgedge]

Didn't intend the wind you up bunnyman - hope you've got your sense of humour back. I have been holding out for someone to say what they thought the problem was in more detail than 'it's pipes wrong' after an earlier idea in this thread that the hot and cold pipes were round the wrong way, turned out not to be right. Thanks Daniel for giving the detail needed. I'm not going to get the previous plumber back - it's a mystery that he could have got it wrong when it was working fine before he moved it and there are only 5 pipes to reconnect (not counting overflow and condensate). Now that it turns out to be more than swapping the hot and cold around, I've decided to fund a local plumber to sort this out (previous plumber is back in Cambridge). If someone watching this thread can quote and is available in the next few days please message me or leave a number etc. Fyi, excuse the caution with just phoning anyone and using this forum to figure things out but I paid someone £140 in last house that I renovated, to get a gas meter connected. It took 40 mins and was connected back to front - it got a bit akward with the gas supplier when the numbers on the metre where going backwards! I'm used to paying £150-180 for a day for plumbing work, so a proportion of that with travel/parts etc would be good. Let me know. Simon