Vaillant ecoTEC plus 831 error code F.22

[handyjohn]

Hi everyone,
doing some work for a customer and one of the jobs is sorting out why they have no heat, but DHW is fine, I pulled the the codes F.22 F.73. water pressure was within limits.
First thing I did was replaced the pressure switch, then reset the boiler. F.73 disappeared F.22 remained along with the fault (no heating)
The heating flow pipe gets hot for the first 13 or so inches, stone cold on the return.. I know I know circulation problem.. I put a screwdriver to the pump and could hear a whirring sound and faint hum, thought I should check the impeller so I started to undo the bleed screw, but stopped due to the amount of water that was released,
I also had a couple of guys with me and they'd finished their jobs and it was lunchtime. I'm thinking diverter or pump. but foolishly already told customer
it sounds like the pressure switch..according to the fault code.. even though the explanation clearly says pressure switch, wire to pressure switch, defective pump, low pressure, or blockage, or words to that effect. being a "cup is half full" kinda guy, I didn't give them the worst case scenario.
yeah alright, I know I've now got egg on my face. And all of you know It's never a good thing to say "actually it's not that it's this"
What I'm looking for is likely culprit. I did read somewhere that F.22 on the 831 was almost always the pump.. this wonderful statement is supposed to have originated from a Vaillant engineer according to some guy on a forum.
Thanks in advance

 

[heliotrope]

Why did you not continue with the checks on the pump?

I've often found that if water shoots 5 foot across the room when
pump screw removed there is likely to be a problem with the pump.

 

[The Goose]

If the pump is a "Wilo" pump then I would think its most likely faulty. They have vaillant written on the label (possibly as well as wilo) and the label is white/silver. The better ones have Grundfoss on them on a black label. Nice and easy to change too!
Before going down that route there could be a blockage in the boiler/system somewhere. If its the older type with the flexi rubber pipes they can block up from there and also the left hand brass block in the boiler where there is a filter in but this is only for the dhw heat ex getting blocked.
Good luck

 

[buckley plumb]

vaillant do a fixed charge repair think its about £200 but they wont cover the plate to plate .used this before on a ecotec pro as pump and press sw was nearly £200

 

[handyjohn]

Thank you heiotrope, the goose, buckley plumb, for a speedy response.
I know now that I should have spent a bit more time testing the pump, usually when undoing the pump bleed screw I've found a bit of hiss and a slight dribble was normal. however that's based on my experience with conventional boilers. We also had another job to go to, and having my 2 guys just watching me and reminding me of the time, led me to the conclusion to leave it, do some research and come back. The amount of water that was released from the bleed screw wasn't as heliotrope described, (shooting 5 foot across the room) I feel that he wasn't expecting me to take him literally.
I did however feel I needed to catch more spillage than normal after a quarter turn of the screw. Didn't remember seeing any rubber hoses, did see a 2009 build date somewhere though.
Not quite ready to call the cavalry just yet. So guys, does everyone agree next visit I should arm myself with a pump??
Again thanks guys.

 

[jtsplumbing]

You must be chargeing a good rate 3 men to look at a boiler fault !! lol.

 

[handyjohn]

The other 2 guys were plastering and hanging doors, the boiler was "while you're here can you look at my boiler" so I said yes. The job is in London nw4 if anyone feels the need to join in..

 

[buckley plumb]

pumps are £130 plus vat so would not change unless your sure . also if its wilo you will need to change the whole pump and housing . thats why i said call vaillant they charge £200 inc parts by the time you have bought the pump and fitted your bill will be more .