Maybe I should get the boiler serviced…?

[Tim+]

But would it have helped?

My 18 yr old Vaillant ecoMAX pro has been playing up recently. Running for a while and then stopping inexplicably with a “flame detection” fault code.

Rebooting the boiler always got it going again for a while but not today.

I hate checking on the boiler as it’s in the loft and a pain to get to but couldn’t put it off any longer. I though a good place to start would be the spark igniter/flame detection electrode so I started to remove it. As I slackened the second screw water started to dribble and then pour out of the combustion chamber. Not good!

My first thought was that the heat exchanger had finally sprung a terminal leak but after a bit of thought I realised that if it was leaking, it should be draining down the condensate drain, not filling the combustion chamber.

Long story short, the condensate siphonic trap was full of 18 years worth of crud. This much in fact.

Took a long time to rinse out and shake all the crud out and because of the one piece moulded design, it’s impossible to get inside it to clean it properly but I managed to clear a lot out.

Put everything back together (using a new gasket left over from last time I “serviced” the boiler about 5 years ago) and woohoo, it fired straight up!

So, a couple of questions, would any boiler servicing have prevented this? It’s quite a task removing the condensate trap and I very much doubt that any service includes trap cleaning.

Secondly, whilst my boiler is working the fan keeps speeding up and slowing down. I don’t think it’s always done this but I can’t remember whether this is “normal” for this boiler or not.

(Boring video of boiler fan noise)

If it’s *not* normal, what would be the likely cause?

Tim

[Spike]

Yes!

My condensate trap is cleaned out at every service; usually there’s a couple of dead bugs and bits of leaf in it.

It is normal for a modulating boiler…

Couldn’t get the videos to run.

Pass.

[Harry Bloomfield Esq]

It depends on the level of service ordered, at its most basic, they will just check the combustion is OK.

It should speed up and slow down, with the demand for heat and the level of modulation. I think when they first fire up, they do a purge, then they fire up running flat out, then settle.

[alan_m]

Have you got the service manual, or can get one from the Web?

I have a fairly new Vaillant boiler and on its first service the condensate trap was cleaned. It's mentioned in the service/maintenance part of the Installation and Service Manual.

The technician who performed the service followed the Vaillant check sheet and the covers off service took around 45 minutes. The magnetic filter was also flushed. This service was from a small local 2 or 3 man central heating company.

I'm aware that some routine services seem to only check the flue gasses with an analyser and the technician may be in and out the house in 10/15 minutes. My mother was once on a service contract with BG. They did turn up once a year but were in and out pretty quickly. She then had a fault and part of the same contract a technician came out for the fix. His first comment on removing the case was the boiler didn't look if it had any service for a long number of years!

Your link seems to stall for me but is it the fan constantly changing speed or are you hearing the boiler modulating up/down?

[Brian]

No if the hole is large enough (been there- the chap who came to fix it got a soaking when he removed the inner cover.

Not surprising if the boiler hasn’t been serviced. I normally watch when ours is serviced and I’ve noticed they always clean the trap.

Certainly the company that does ours have always cleared the trap. We have a service contract and they do a service / check every year.

That said, last winter, the pipe froze and we had a problem with water in the burner.

Our boiler was a number of fine ‘slots’ - possibly ceramic?- which make up the burner ‘bed’. It was saturated. The chap spend ages drying it out with a hair dryer before the boiler would fire up.

I’ve rearranged the way the pipe drains, hopefully it won’t freeze again.

[Tim+]

I suspect boiler design has improved then. It’s really quite a convoluted process to clean out my condensate drain. First the boiler outer cover has to come off. Then the inner “cover”. Then an inner plate that protects all the electronics and seals the boiler compartment. Then the HT coil for the ignitor. Then the hoses connecting the condensate drain. Only then can you access the retention screws and remove the whole siphonic trap. Mine doesn’t seem to have been designed to make this at all easy!

Tim

[John Rumm]

Mmmm yummy :-)

(must admit I tend to get little if anything in the condensate trap - the only time it collected some slightly dodgy looking water was when the main HX sprang a leak!)

Yes, a condensate trap check and clean if required is a standard bit of the service.

If it like that on mine (ecoTec 624) then it is tucked down the back on the right hand side - it takes a bit of fiddling to slide it out and then wiggle it to the left where there is enough space to get it out...

However if doing it frequently I expect one would get quite adept at it.

I can't play the video at the mo - just says "your video will be ready soon"

But it is a modulating boiler, so you can expect the fan to change speed depending on the heating load. Especially just after it fires on a slightly warm system - the temperature of the return water can vary a bit depending on how much residual heat there is still in it. That will vary with which rad or pipe it has been sitting in.

(if you listen carefully you can often hear the stepper motor on the gas valve click as it adjusts its power setting)

knackered fan?

[Tim+]

Having had a quick squint at some videos the design has been vastly improved. Doesn’t look like any disassembly or tools are needed! Fairly major strip down needed in mine. Still, hopefully that’s it good for another 18 years. ;-)

Tim

[Andrew]

And up in the loft it is in an environment that cycles through a far wider range of temperatures than one installed within the living areas. Notably, very hot in summer when the boiler fires up far less, resulting in a greater chance of the condensate trap drying out before it gets flushed out.