Float valve problems

GDB2222

Freddythefearlessfish said:

ThisIsWeird said:

FtFF, I suspect, like GDB, that there's summat else amiss.

This is def the ball valve in the SMALL F&E tank? In which case, it should hardly ever open to top up that tank. If it's topping up regularly, then you have an issue that needs sorting - a leak, or possibly an overheating system. So that's the first Q to ask.

As for 'hammer',  what exactly do you mean? ONE big thump in the pipes as the valve shuts off? Or a foghorn? Or a repeated stammering noise? 

As for the quality of the BV, I suspect it's as good as any such brass valve. 

Correct.  Agree it should hardly ever open.  As far as I'm aware it wasn't regularly, or ever topping up to my knowledge.

As for my description of hammer.  After a full reset (turning off the stop !!!!!! draining from the top tap, down the bottom tap in the house, and then turning the the stop !!!!!! back on, running the taps for a bit, getting everything back to hunky dory) I was getting a single thump.  About a week later I was getting serious hammer every time the cold water was turned off - foghorn like.

Thanks for the pointer that the quality is likely to as good as any other.

If there was air in the pipe after turning off the water, that would have an interesting effect on the ball valve until the air had all come out.  You would only notice it when the ball valve opens, which might be weeks after you drained the pipes.

ThisIsWeird

FtFF, I think back to some basics.

You have a 'part 1' valve, which I presume replaced what was also a P1 ball valve? It 'works' the same way, so isn't the cause of your problems. A Part 2 valve is the approved type, tho', as the water comes out the top of the valve, and is then pointed downwards into the tank by usually a U-shaped plastic tube. The idea is that the water outlet of the valve cannot go under the tank's water level, which - under some rare circumstances - could allow the contaminated tank water to back-syphon down the mains pipe, clearly a not good thing. 
P2 valves are also seemingly easier to adjust for water level, but the P1 is ok for this - you just bend the arm.

Does the supply pipe to the valve have an isolating valve on it, so you can remove the b-valve without having to shut off the whole house mains? If not, that would have been a useful thing to add, but hey. The next time you need to shut off and part-drain the mains in order to remove the b-valve, bear in mind it's the highest point in your system (along with a CWS?), so only run a cold mains tap for 2 seconds in order to drain enough water from that pipe.

For checking and cleaning the BV, you don't even need to drain at all, as any drips will be within the tank.

Ok, mains sc off, check BV isn't getting a supply (push the ball under), remove the ball (it'll just annoy), and remove the BV - placing a towel or container under the pipe end tobesuretobesure.

Undo the knurled brass cap at the end of the BV and observe how the 'piston' moves back and forth as you move the arm up and down. Remove the split pin holding the arm at the BV, and wiggle the arm off. Shake out the piston, and check the rubber washer on the end - is it clean? Check (can you disassemble further?) The inlet where the washer pushes against - is that clean too?

Give the washer a smear of silicone grease if you have any, and reassemble. Test by blowing into it and see if it shuts you off fully and with ease. Refit.

Check height of where the BV is mounted and compare with overflow outlet - hopefully the overflow is lower, so water level should not reach the BV? If so, although P2 is water regs, it ain't the end of the world.

Fit ball. Turn on water and check valve works. Look at water level, how close to the overflow it is, and press ball downwards to see what the shut-off level of it is. The ultimate check is to drain off (use a pan to scoop into a bucket) tank water until the BV operates, and then let it fully stop - no drips. You want the water level to be a good 50mm below the bottom of the overflow outlet. (Water expands when heated, so that currently low level will be going up and down in normal use, but without the BV operating.

Bend the arm to suit. That's the new BV set up.

ThisIsWeird

Ok, noises. You have three - spluttering, hammer, and foghorn. 

The spluttering seems to have been a one-of, caused by expelling air from the pipes. Try not to drain the pipes as much in future. In any case, it should pass quickly - burp.

Then there's 'hammer'. This can be a single clunk from the pipes when a valve or tap is turned off (usually quickly), or can be repeated knocking - clunk-clunk-clunk. For a single clunk, it's usually that a pipe somewhere is not clipped or supported well enough to stop it jumping with the change in pressure when a tap closes. Or, it can be caused to a generally 'ok' system when the mains pressure has increased. What's your mains pressure like - does the cold kitchen blast out with considerable force (called the wet pants test)?

Repeated hammer is usually caused by a loose, shaking valve washer in a device in the circuit, say the mains stopcock or the ball valve, and occasionally even by a valve in another circuit which is not being used at the time, like a toilet cistern. But, more likely in your case, is that the pipe supplying the BV is shoogly enough to start slowly resonating, wobbling back and forth as the BV tries to shut off; BV closes, pressure in pipe therefore increases, pipe swells slightly and bends, also slightly bending the BV mounting, BV opens a tad, pressure drops, pipe 'shrinks', springs backwards, BV shuts rapidly, pressure jumps...

Is there a large metal washer squashed against the tank side under the BV fitting? That's there to reduce side flex which can cause this. Is the supply pipe unsupported and air-borne as it reaches the tank? That may need securing better.

That sort of stuff.

Oh, the foghorn is a faster resonance on the bv's rubber washer as it vibrates with the water rushing past it - think of it as a musical - reed - wind instrument. Again, a loose or hardened washer, or simple too high a mains water pressure. Have you done the W-P test yet?

Alter_ego

Freddythefearlessfish said:

ThisIsWeird said:

FtFF, I suspect, like GDB, that there's summat else amiss.

This is def the ball valve in the SMALL F&E tank? In which case, it should hardly ever open to top up that tank. If it's topping up regularly, then you have an issue that needs sorting - a leak, or possibly an overheating system. So that's the first Q to ask.

As for 'hammer',  what exactly do you mean? ONE big thump in the pipes as the valve shuts off? Or a foghorn? Or a repeated stammering noise? 

As for the quality of the BV, I suspect it's as good as any such brass valve. 

Correct.  Agree it should hardly ever open.  As far as I'm aware it wasn't regularly, or ever topping up to my knowledge.

As for my description of hammer.  After a full reset (turning off the stop !!!!!! draining from the top tap, down the bottom tap in the house, and then turning the the stop !!!!!! back on, running the taps for a bit, getting everything back to hunky dory) I was getting a single thump.  About a week later I was getting serious hammer every time the cold water was turned off - foghorn like.

Thanks for the pointer that the quality is likely to as good as any other.

You have said it is the Feed and expnsion tank for CH. Then you mention draining down taps. There are no taps on the CH system. Are you sure of your facts

ThisIsWeird

I hope he meant that he drained a tap in order to relieve the mains pressure from the ballcock he was removing - which just needs one second's running. I don't think he actually drained the tank. But I don't know!

Section62

ThisIsWeird said:

FtFF, I think back to some basics.

You have a 'part 1' valve, which I presume replaced what was also a P1 ball valve? It 'works' the same way, so isn't the cause of your problems. A Part 2 valve is the approved type, tho', as the water comes out the top of the valve, and is then pointed downwards into the tank by usually a U-shaped plastic tube. The idea is that the water outlet of the valve cannot go under the tank's water level, which - under some rare circumstances - could allow the contaminated tank water to back-syphon down the mains pipe, clearly a not good thing. 

If the warning/overflow pipe is set too high, or blocked, then the outlet of a P2 valve could be submerged below the level of the water in the tank/cistern.

There is some greater protection from a P2 valve compared to a P1, but in terms of water level it is only the height difference between the outlet level of the two types.

The correct protection against backflow is to have the warning/overflow pipe level set sufficiently lower than the inlet level and periodically check the warning/overflow pipe isn't blocked.  If the latter can't be achieved then consider fitting a check valve on the supply... although this will only protect against backflow, it won't stop the tank/cistern overflowing, so occasional maintenance of the warning/overflow pipe makes more sense.

ThisIsWeird

Section62 said:

ThisIsWeird said:

FtFF, I think back to some basics.

You have a 'part 1' valve, which I presume replaced what was also a P1 ball valve? It 'works' the same way, so isn't the cause of your problems. A Part 2 valve is the approved type, tho', as the water comes out the top of the valve, and is then pointed downwards into the tank by usually a U-shaped plastic tube. The idea is that the water outlet of the valve cannot go under the tank's water level, which - under some rare circumstances - could allow the contaminated tank water to back-syphon down the mains pipe, clearly a not good thing. 

If the warning/overflow pipe is set too high, or blocked, then the outlet of a P2 valve could be submerged below the level of the water in the tank/cistern.

There is some greater protection from a P2 valve compared to a P1, but in terms of water level it is only the height difference between the outlet level of the two types.

The correct protection against backflow is to have the warning/overflow pipe level set sufficiently lower than the inlet level and periodically check the warning/overflow pipe isn't blocked.  If the latter can't be achieved then consider fitting a check valve on the supply... although this will only protect against backflow, it won't stop the tank/cistern overflowing, so occasional maintenance of the warning/overflow pipe makes more sense.

Hence my further comment, "Check height of where the BV is mounted and compare with overflow outlet - hopefully the overflow is lower, so water level should not reach the BV? If so, although P2 is water regs, it ain't the end of the world."