Vaillant ecomax 835e - losing pressure, no hot water/heating

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Hi,

I was hoping someone on the forum could help me regarding problems with a Vaillant 835. Here's how I have got to a boiler with no hot water/heating.

I noticed that the hot water was going cold in the shower and that the boiler kept losing pressure (had to be topped up every day) about 2 months ago. My insurance company sent someone round who re-pressurized the vessel. This seemed to fix the pressure problem for a while, but not the hot water problem.

To fix the hot water problem, the company came back and replaced the "NTC". This didn't solve the hot water problem and the pressure problem resurfaced.

They have been around again and have now replaced the PCB, which has solved nothing.

This has been rumbling on for about 2 months now and the boiler has got must worse during this time. The last time I spoke to the engineer he said "maybe a powerflush is needed, maybe a new boiler". To be honest, I've lost all faith in the company as I'm without hot water or heating during a pretty chilly time!

I tried to re-fill the boiler last night and (with no hot water demand and heating switched off) the pressure guage fell to zero again within 30mins. I filled it up again this morning (6am), switched the heating on, but the pressure dropped again at around 11am. I'm not sure the heating was actually doing anything as the radiators were lukewarm and d40 was at 70c, d41 was at 41c.

The boiler is seven years old and has been serviced every year. There's no magnaclean device fitted and from what I've read around the forums/other sites the plate h'ex sounds like its blocked. I'm not sure this would cause all the problems I've mentioned above.

Thanks for reading the post and for any advise!
 
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Unfortunately you dont get the best people working for those firms.

Their only interest is to get out as quick as they can.

Obviously something is leaking and that should be easy to find.

I am glad that I dont need to accept the very poor service those firms give.

Tony Glazier
 
My insurance company sent someone round who re-pressurized the vessel. This seemed to fix the pressure problem for a while, but not the hot water problem.

To fix the hot water problem, the company came back and replaced the "NTC". This didn't solve the hot water problem and the pressure problem resurfaced.

They have been around again and have now replaced the PCB, which has solved nothing.

Pressure drop = leak, simple as that. If the ev is completely flat or gone, this could contribute to it.

The guys you had around were clearly not engineers, but parts changers.

Probably little wrong with the boiler.

You can only expect moneys' worth from a powerflush if dhw goes hot/cold/hot etc.

First suspect is 3 bar valve. find a 15 mm pipe outside the rear of the boiler and below. Tie a sandwich bag over it with rubber band and fill boiler to 1.5 bar, and fire up. If you find water in the bag after a couple of hours/days, there's your problem.

Finally, the vast majority of people doing insurance work are muppets.
 
When the expansion vessel loses pressure you can pump it up, but like a leaky bicycle tyre, the air is going to leak out again.

Insurance monkeys get a fixed rate per repair providing the repair lasts a set number of days - typically 14.

So faced with finding a new expansion vessel and possibly also the pressure relief valve that will also be in a poor state, or putting some air in the old one and getting paid £100, he took the obvious option.

Dream ticket £200 a year maintenance contracts are often a waste of money, and most tradesmen here would not earn a suitable living working in this industry.

Consequently, as a generality, you get gas technicians very low down the Darwinian scale working in this area, particularly in London, where there are plenty of jobs for good gas engineers.
 
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To answer your question, you may or may not need a new HW HEX, but until you stop the pressure/water loss it isn't speculating on the HW fault.

If you had a magnaclean it would have started leaking by now, waste of money. Filters are only needed on poorly prepared or severely corroded systems.
 
I have the same boiler and have suffered the same problems. It sounds as if you have 2 separate problems, one being a small leak in the central heating system and the other a fault in the hot water side of the boiler. I traced the leak in my heating system myself after the so called engineer failed to find it, it was a radiator valve in the kitchen, the leak was very small and not visible but feeling around the valve there was a trace of water, it was enough to depressurise the system overnight. I changed the valve and haven't had a problem with depressurising since. The problem with the no hot water took British Gas a week to fix, they didn't have a clue and ended up changing nearly everything in the boiler. I was really glad that I had a service contract. My boiler was 4 years old at the time. From talking to other people with Vaillant boilers it would appear that it is a common problem with this boiler.
 

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