Boiler Pressure Problem

lamialex

Hello,

I have just bought a property and the boiler has never worked. At the beginning we had hot water but no heating and after 3 weeks, we also don't have hot water.
The boiler is a Vaillant Ecotec plus 415, I have looked at the manual online and it always gives an error related to water pressure. The error now is F22 which is again related to water pressure. Everytime we reset it, the boiler starts and then stops and gives a water pressure problem code. We tried to pressure the boiler but cannot find the valve/pipe that fills it up with water. This type of boiler has the gas pipe underneath and two pipes at the top : R and F. As you can see on the pictures, many valves and I have checked and there are all open. So I am a bit lost now. Any idea which valve pressurises the boiler or where I should look? Thanks a lot.
Alex

Belenus

two pipes at the top : R and F.

R and F are presumably return and flow to and from the boiler to the central heating radiators and hot water cylinder, otherwise I can't help you.

Can you identify the cold water feed to the hot water cylinder?  The filling loop to pressurise the boiler is normally taken from that cold water feed.

nofoollikeold

1. The Vaillant 4nn series boilers are open vent boilers.  They can have system water supplied by:
1a. A small (Feed and Expansion (F&E)) tank, normally in the loft.  OR
1b. Pressurised water in an expansion vessel.
2. Check that your system does not have an F&E tank.  The fact that you have an F22 error suggests you won't have one.
3. Assuming it is a pressurised system:
3a. Because it is basically an open vent system, the expansion vessel which maintains the water pressure and copes with expansion is not internal to the boiler.
3b. You will have an expansion vessel somewhere on the system.  It will be red in colour, cylindrical with slightly domed ends.
3c. The expansion vessel will have either attached to it or close by, a metal braided hose - the filling loop.  This should have a valve at each end, but don't be surprised if it only has one valve.  One end of the hose is connected to a source of mains water via the valve, and the other end is connected to (preferably) the system return pipe, but sometimes to the flow.  The flexible hose is supposed to be removed, but rarely is, once the two valves have been closed.  It is possible that it has been removed, in which case you should find two pipes, fairly close together, with a nickel plated knurled end cap screwed on.
3d. To connect the hose if disconnected, make sure both valves are closed (levers / handles at right angles to the pipe) remove the caps and screw the ends of the flexible hose on in place of the caps.
3e. Pressurise as normal.  I.e. open each valve, watch the pressure gauge, and when it reaches 1.3 or 1.5 bar, close one valve then the other.  Remove the filling loop if you want to follow the letter of the regulations.  

lamialex

Thanks for the help.
There are two tanks in the loft, a big one and a smaller one. Could the small tank be the F&E tank?
That makes sense that the vessel maintaining the water pressure is external but would it be in the loft when it's a tricky place to get to? our loft hasn't been converted.
There is a water pump at the top of the boiler on the left for the shower and I think the filling loop is there as you can see on the last picture but I need to have a better look under the sound isolation the previous owners have put around it.

lamialex

looking at google search, the big tank in the loft has the ball in it so that must be the F&E tank, 2 pipes coming out of it with 2 valves and both opened
the smaller one i can't see inside and it's higher up than the big with pipes coming out of it but no valves

lamialex

and can't see an expansion vessel

Bendy_House

lamialex said:

looking at google search, the big tank in the loft has the ball in it so that must be the F&E tank, 2 pipes coming out of it with 2 valves and both opened
the smaller one i can't see inside and it's higher up than the big with pipes coming out of it but no valves

You really need to have a peek inside that higher, smaller tank, as - if it has water in it - it'll almost certainly be the F&E tank. This would mean that your system is NOT sealed, and can NOT be repressurised. It is, instead, automatically kept full of system water (ie the water that circulates in the boiler, radiators, and heating coil in the hot cylinder) by this tank.

If this tank has failed somehow - eg the ballvalve has stuck closed and the tank has emptied - then your boiler may well have a safety sensor in it to prevent it from firing up, which would be a good thing. If, however, that wee tank is full of water, then chances are your F22 fault means something else.

A simple test you can do - open a radiator bleed valve, and see if water comes out, and how squirtily. Try a rad on the top floor, as that will be under the least pressure, so if that squirts, you should be fine.

Bendy_House

Is there an analogue (needle) pressure gauge on the boiler control panel?

When the digital display says F22, does it alternate with another figure, such as 0.6 or so?

This: https://www.vaillant.co.uk/for-installers/products/ecotec-plus-412-415-418-424-430-and-435-3328.html suggests it's an open-vent boiler, so will have an F&E tank. It can also seemingly be set up as a 'system' boiler - so sealed, pressurised and with no F&E tank - but this will involve the red EV mentioned by NFLO. The installation instructions linked from there makes no mention of an F22 code! But that IS usually the 'low pressure' code.

So - pressure gauge? Reading on display? Is there water in that F&E tank?

lamialex

no analogue pressure gauge, it shows the pressure on the electronic display and at the moment it says "- bar" as you can see from the picture
i will have a look in the loft again and check those two tanks
I tried to find the filling loop but no luck, the only metal braided hose i can see are the ones near the shower pump
i'll have a look in the loft to see if i can find it there

lamialex

so I had a look in the loft, here are a picture of the two tanks, I pressed both balls and they are both working but it looked like the small tank looked rather empty, is that normal?
and I just remembered my partner made a hole in a radiator pipe while lifting up wooden boards and it got a lot of water out before he could fix that pipe, a few days later we had no hot water on top of no heating, before it was just not heating  so I am thinking it must have dropped the water pressure even lower.

Bendy_House

This remains a mystery!

Yes, the wee tank doesn't tend to have much in it when the system is cold, perhaps half-fill. The reason is, the system water expands when hot, and that is pushed back up in to that tank - it would then be a good 3/4 full or so.

I suspect that tank is still in operation, so your boiler type IS 'vented', unpressurised. I DON'T see 'bar' in that pic of your display. 

If your system was unvented/sealed/pressurised, then almost certainly that wee tank would have been disabled, and the supply to it shot off. And you definitely would instead have a (red) Expansion Vessel installed somewhere pretty obvious. With a filling loop likely to be nearby.

Your boiler seems to be BEHAVING like one with not enough pressure - IE, a sealed type - but it APPEARS to be the type supplied by an F&E tank, so no pressure issues.

Have you tried bleeding a radiator to see if water comes out reasonably forcefully?