F22 - Vaillant Ecotec Plus 831

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Hi guys. I've had to re-pressurise my combi since about November. It used to be a few weeks between re-pressurising but now it's just a matter of 3 or 4 days.

Clearly it needs fixing before It gets to the point that I can't re-pressurise it any more, plus I read that does more damage.

From my research I'm hoping it's a part in the boiler such as possibly the expansion vessel or a pump rather than any pipe leak under the ceramic tiles in my kitchen.

This boiler has been a champ since it was installed in 2013. I have to admit that it hasn't been serviced since 2015.

I called Vaillant today who said for £51 a month for a 6 months plan they can come and repair, including parts, regardless of what needs fixing or replacing.. If it's not repairable it would just cost £95 callout.

And if I didn't do the 6 month plan, they said it would still cost £311 not including parts.

Do you think I should go for the 6 month plan? And of course, I would assume Vaillant will have more expertise on my boiler than another company. Or go for an independent gas safe engineer which may cost less or more than Vaillant?
 
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No harm in going for the 6 month plan including parts replacement, does it include a service? Failing that it’ll be a leak from somewhere or an expansion issue. Don’t know how much an independent engineer would charge.
 
No harm in going for the 6 month plan including parts replacement, does it include a service? Failing that it’ll be a leak from somewhere or an expansion issue. Don’t know how much an independent engineer would charge.

Yes, I asked the guy at Vaillant about a service and he said that if I'm happy to increase to £65pm instead of £51pm for 6 months, that would include a service. Which I should probably do.

If it's a leak, are we talking under the floor, or more likely a pump? I found an article, wonder what you think.

"A Gas Engineer will need to troubleshoot the boiler to determine whether the F22 fault is related to:

  1. Lack of pressure
  2. Lack of water
  3. Both of the above
Leaks are one of the most common reasons a boiler loses pressure (and water). They can come from radiators, towel rails, radiator valves, pipe work, air vents or even expansion vessels.

Another common cause is a build-up of air in radiators.

However, a faulty pump could also be the culprit. A lot of older Vaillant boilers used Wilo pumps. They are prone to faults and over time they seize or start to leak. This would be the cause of low pressure and lack of water
."
 
A leak can occur on any part of the system, if you look at the safety discharge pipe outside, it might be dripping, if this is the new it’s expansion vessel or prv. If the boiler was leaking for the amount of time you’ve stated, I’d have expected you to have water dripping from the boiler casing. If it’s on the rads/pipes then under the floors, pipes to valves and nuts on valves/entry points.
 
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If you can do without heating for a few days, pressurise system, isolate boiler from system (if iso valves are in working order). Leave for 2-3days and keep a check on pressure gauge. If it drops boiler leak. If it drops when you open iso valves back up, leak somewhere on system.

Need to check if your boiler can run hot water with flow and return valves off, else you can't use boiler during this test.
 
A leak can occur on any part of the system, if you look at the safety discharge pipe outside, it might be dripping, if this is the new it’s expansion vessel or prv. If the boiler was leaking for the amount of time you’ve stated, I’d have expected you to have water dripping from the boiler casing. If it’s on the rads/pipes then under the floors, pipes to valves and nuts on valves/entry points.

Nope, no water ever dripped from the boiler casing. I checked the discharge pipe a few weeks ago and didn't notice any dripping either. But I'll check it again tomorrow.

Do you think though that if there's a leak that it's probably more likely to be in the boiler or at least somewhere more easily accessible than pipes buried under the floor? It's a concrete floor with pipes laid and ceramic tiles over that.


If you can do without heating for a few days, pressurise system, isolate boiler from system (if iso valves are in working order). Leave for 2-3days and keep a check on pressure gauge. If it drops boiler leak. If it drops when you open iso valves back up, leak somewhere on system.

Need to check if your boiler can run hot water with flow and return valves off, else you can't use boiler during this test.

I'm afraid I have absolutely no clue how to isolate the boiler plus the weather is still a bit too cold without heating.
 
Can't you buy/borrow some electric heaters to tide you over while you do the test? It's what you'd have to do if your boiler failed right this minute! Or your gas supply! Some small sacrifices may save you spending on a boiler contract that proves the boiler is fine as the leak is on your system.
And get busy checking all exposed pipework and fittings for leaks with blue paper towel. Look at ceilings for any signs of damp.
 
Actually yeah, I do have a small oil filled electric radiator.

"Isolate boiler from system if iso valves are in working order. Check if your boiler can run hot water with flow and return valves off".

Ok so to isolate it seems from what you're saying I just have to turn two valves off, the flow and return valves. Where would I find those? There's two taps under my boiler and when I have to repressurise after an F22 error, I turn those on and then off once I've reached 1.5 bar. Those aren't the iso valves I take it?
 
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No, there’s 4 isolation points (3 if it’s a cylinder setup) under the boiler where the pipes enter/exit the boiler made from brass, using a 4mm Allen key turn the x2 outer ones all the way, to the stop point, you’ll know when.
 
No, there’s 4 isolation points (3 if it’s a cylinder setup) under the boiler where the pipes enter/exit the boiler made from brass, using a 4mm Allen key turn the x2 outer ones all the way, to the stop point, you’ll know when.

I've uploaded some photos from different angles. As you can see, below the boiler is boxed in. But I'm assuming/ hoping they allowed for access to important valves and I'm guessing there's no allen key points lower down where I can't reach.

There's 6 brass pipes but are you able to see anything here that would be the isolation valves I need?

20200201_131532.jpg 20200201_131247.jpg 20200201_131125.jpg 20200201_131031.jpg
 
Ok, so these two circled in blue are your flow and return
 

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Ok, so these two circled in blue are your flow and return

Awesome! Thanks for circling those, makes it very clear and easy for me to know how to do it now. Thanks given, my pleasure.

Don't use the wrong allen key OR be too over exuberant else you'll round them out in the brass and knacker them... Gentle steady force and they only turn 1/4.

Thanks dilalio. Looks like I have a 4mm and it fits perfectly. :)

20200201_153359.jpg

As you said it needs 2 to 3 days testing, I'll do this test on wednesday as I have friends coming here monday and tuesday and I want them to feel comfortable.

What direction do you think is likely to close the iso valves, clockwise or anti?

As you mentioned in an earlier post, closomg the valves might prevent the boiler running hot water to my taps and shower. Fingers crossed it doesn't do that.

Finally, would you recommend I pressurise my boiler to 1.5 bars before doing the test? 1.5 is what I have been doing as I believe that is the standard setting?
 
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I've just had a quick go in one of the iso valves and it seems tight. I tried turning in both directions and it hasn't moved yet. Don't want to force anything.

By the way, just to let you know, I pressurised yesterday to 1.5 or might have been a bit higher, can't remember. It's now sitting at 1.0.
 
The pressure vessel will have lost its charge. (They always do) with no pocket of air in the system, it'll only take a tiny amount of water to leak to drop .5bar.
The vessel will need recharging to .75 bar. (While the boiler is empty & drain offs open) the pressure sensor will need cleaning & you're also well overdue for the burner seal to be changed. Oh, & the pressure relief valve will need cleaning.
Hope this helps. It'll take an engineer about an hour all in all.
 

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