How do I adjust the fill level on my cistern?

[Mr M]

How do I adjust the fill level on my cistern?

I need to reduce the amount of water that's coming into the cistern after a flush as it's constantly trickling into the WC pan. See pictures of the insise of the cistern below:

 

[Alec_t]

it's constantly trickling into the WC pan

One of two reasons:
a) water level really is too high, so excess goes down the central overflow pipe,
b) water level is correct but the flush valve isn't sealing properly, so the inlet valve opens partially to let a compensating trickle of water in.
Which is it?

 

[Mr M]

When it fills, the water level doesn't get up anywhere near as high as the open ended pipe in the (is the part that's coloured all white in the middle of the cistern that has 'Siamp' on the top of it called the outlet valve? and is the other one that's a mixture of white and grey colours called the inlet valve?)

When flushed, the water level fills upto and then just slightly over the lowest part of the other valve that's at the side of the cistern (Inlet valve?). As soon as it reaches that level, the grey part lowers down and the water shuts off. Is it supposed to get that high before the water shuts off or should it shut off sooner before it gets to that level?

 

[Alec_t]

Sounds as though the water level is about right and the SIAMP flush valve isn't sealing properly. I'm not familiar with that brand.

 

[Elkato531]

Fill valve looks like Flomasta from Screwfix but seems to be working correctly.
Flush valve is Siamp Optima 49. Easy twist and lift out to check seal. Sometimes just needs the limescale scraping off the seal and the seat. A new seal will be less than a fiver online. New valve is about £20 from plumbers merchant if required.

 

[Mr M]

Fill valve looks like Flomasta from Screwfix but seems to be working correctly.
Flush valve is Siamp Optima 49. Easy twist and lift out to check seal. Sometimes just needs the limescale scraping off the seal and the seat. A new seal will be less than a fiver online. New valve is about £20 from plumbers merchant if required.

Thanks, that's great information. I'll see if I can take the top part of the Siamp flush valve off to have a look at it inside/lower down.

If I grab the body, do I literally just twist it (presumablty anti-clockwise) and it should then come off? There's no securing clips or anything like that that need to be unclipped or removed first? I don't want to force it and possibly cause damage to it.

Provided I can get it off, I'll give it a clean regardless and inspect the seal.

 

[Elkato531]

Yes, anticlockwise turn then lift out. There are video links on the Siamp website showing how.

 

[ChrisJP]

Thanks, that's great information. I'll see if I can take the top part of the Siamp flush valve off to have a look at it inside/lower down.

If I grab the body, do I literally just twist it (presumablty anti-clockwise) and it should then come off? There's no securing clips or anything like that that need to be unclipped or removed first? I don't want to force it and possibly cause damage to it.

Provided I can get it off, I'll give it a clean regardless and inspect the seal.

I suspect an awful lot of water is wasted via leaking flush valve seals. Why we moved away from the traditional siphon flush I've no idea - this cannot leak under any circumstances. Its only failure mode is becoming more difficult to initiate a flush and this can easily be fixed by replacing the diaphragm.

 

[Mr M]

Yes, anticlockwise turn then lift out. There are video links on the Siamp website showing how.

I'll give it a go and see how I get on. Thanks for the responses so far.

 

[DP]

When it fills, the water level doesn't get up anywhere near as high as the open ended pipe in the (is the part that's coloured all white in the middle of the cistern that has 'Siamp' on the top of it called the outlet valve? and is the other one that's a mixture of white and grey colours called the inlet valve?)

When flushed, the water level fills upto and then just slightly over the lowest part of the other valve that's at the side of the cistern (Inlet valve?). As soon as it reaches that level, the grey part lowers down and the water shuts off. Is it supposed to get that high before the water shuts off or should it shut off sooner before it gets to that level?

Water level needs to be at the line marked in the cistern which it is at in one of the pictures

 

[Mr M]

I have now removed the flush valve and have better access to the fill valve. I'll report back regarding the flush valve later on.

Regarding the fill valve:

Water level needs to be at the line marked in the cistern which it is at in one of the pictures

There are two lines that are scribed into the inside side wall of the cistern. The cistern is currently drained of water but you can see the two lines on the photo below. The water level fills up to the lower of the two lines before shutting off.

Fill valve looks like Flomasta from Screwfix but seems to be working correctly.

I had a look on Screwfix's website and yes you are correct, my fill valve does appear to be their Flomasta product.

When filling, the water level gets to the top of the white area on the fill valve that I am pointing to in the photo below and then its gets very slightly above and the water appears to start entering the fill valve over its top and that causes the grey parts (which I assume ar like a float or a replacement for the old ballcock?) to pivot and the water supply then shuts off.

On flushing, as soon as the water level starts to drop, the grey parts pivot back to their previous position allowing the water supply to start filling the cistern again, until it reaches its fill level.

I am assuming that is the way the flush valve is supposed to work? and that mine is working correctly?

 

[Alec_t]

I am assuming that is the way the flush valve is supposed to work?

It's the way the fill valve is supposed to work. The flush valve has a disc seal at the base, which won't seal properly against its seat if there is grit or gunge present.

 

[Mr M]

It's the way the fill valve is supposed to work.

Thanks. I just wanted to make sure that the fill valve was actually working correctly as I am not that familiar with how it operates.

The flush valve has a disc seal at the base, which won't seal properly against its seat if there is grit or gunge present.

I have now removed the top section of the flush valve. The rubber seal looks in relatively good condition. See the photos below.



I'll remove the rubber seal and give everything a thorough clean before refitting it. I'll also give the strainer (shown in the photo below) that the top section fits into a clean as well before refitting the top part back to it.



I'll also thoroughly clean-out the bottom of the cistern as well as there are small bits of debris which need to come out before I refill the cistern.

 

[Elkato531]

Fill valve working correctly. It is height adjustable if you wanted to raise the water level. Below the float assembly there is a small grey clip on the stem which can be removed. The top part can then be rotated slightly and will then move up or down as required. The rim of the float bowl (where you have your finger) should be aligned with the water level. Rotate back to hold position and insert the locking clip. Can be a bit fiddly especially if you're working blind.
Maybe worth replacing the flush seal now that you know how. The rubber does stiffen and perish over time.