Does this pipe layout look correct?

[mk2phil]

I posted a question last week regarding the water pressure/flow in our shower. The hot water pressure is pretty bad whereas the cold is superb.

The pump supplies both the shower and the bath taps, and I've noticed that when the hot water pressure/flow starts to drop in the shower, if I tuen the shower off and run the hot water tap in the bath it'll cough and splutter some air out, then it'll run but the pressure will build up and then slow down again.

Then when I turn the shower back on the pressure is pretty good for about 30 seconds before it drops again. All the way through this the cold water pressure/flow to the shower and taps is spot on.

I've been up in the loft and checked the cold water tank when the shower is running as I thought maybe it was emptying faster than it could fill but this isn't the problem - than tank is massive and fills adequetely. I just wanted to check the pipework looked correct before I attribute the problem to the pump.

This is how its set out:

The little air valve on top of the hot pipe that comes out of the pump is open too so I dont think thats the problem. Got a feeling a new pump is going to cost a fortune - its a hansgrohe/Axor/Pharo one yet I cant seem to find them anywhere.

Any help much appreciated, thanks

 

[oilman]

What's that air valve doing there? Should be removed and the pipwork installed so air vents via the vent pipe.

For all the pictures, nobody can tell what cgoes where for sure. You need some labels.

 

[Onetap]

Is that a Warix flange on top of the cylinder?
Check the connections against the manufacturer's recommendations; the open vent & taps should be from the side connection, the shower pump from the top connection.

http://www.techflow.co.uk/qtinstall.htm#fig2


It seems to be wrong, the purpose of the flange is to allow the pump to draw water from a point where it won't draw in the air bubbles coming out of solution as the water heats up. having the open vent and the pump on the same connection can't be right.

The auto air vent shouldn't be there. The air vent can be sealed or could jam shut; the installation is unsafe.

 

[gavinda]

that aav is almost definitely the cause of you spluttering problem. good effort for a diy'er though ... most dont fit em when they should

 

[Gasguru]

Get rid of the air vent, if its a Warix flange the pipes are the wrong way round, fit full bore isolating valves to the pump outlets.

 

[mk2phil]

From the diagram Onetap has linked to it seems to suggest the manual vent should be fitted so I'm not sure what to do..?

I think i'll get the connections swapped over on the flange as this does seemt obe wrong if indeed I do have a Warix flange - how can I tell or do you guys definately know that it is?

Thanks for the help guys, this has been driving me nuts!

 

[ChrisR]

The diagram shows a Manual vent, you've fitted an Automatic one. They have a float in which rises if there's water in the pipe, to shut the ole in the top. But if the water is sucked down, they let air in, which gives a problem like the one you have. If you screw the little plastic cap shut, it should stop air going in. Ie then it becomes a manual air vent.

Looks like a Warix flange to me too. If you'd fitted a SURREY flange, the pipes would have been the right way round. That would be one retro-fit option, but they can be b***'s to fit because they don't swivel, the side(shower) outlet points in whatever direction it wants to when the thing is done up tight.
Remember that the hot water (non shower) pipe does need to be horizontal pretty soon after it leaves the tank or you get convection and heat losses.

More stuff on flanges:
http://www.bathroomexpress.co.uk/pumps/tp60_inst.htm

 

[mk2phil]

So the first thing to do is make sure the cap is screwed in fully?

Actually I have noticed that if you screw the cap all the way down and then have a shower, when you undo the cap afterwards loads of air escapes followed by a few hints of water then it cuts off. Presumably this is air from the tank that is getting cuaght due to the warix flange being the wrong way round.

When opened why does it let air in when water is sucked down - is it a fualty vent i have or should automatic vents never be used on this type of set up becuase the pressure of the water being sucked out of the tank by the pump too much and causes the float to let air in whilst the pump is running?

If I get the pipework swapped over would I still need a manual vent? How often are you supposed to bleed the air off?

 

[Onetap]

So the first thing to do is make sure the cap is screwed in fully??

If you haven't already got one, you need an 22mm open vent pipe discharging over the cold water storage tank, as is shown on all the diagrams posted here. It is not clear whether the pipe going to the right in your pictures has an open vent, but it looks like the AAV has been installed instead of an open vent, for some reason.

There is a risk that the immersion heater thermostat could fail by the contacts welding together; this does happen. The AAV would be unable to discharge the volume of steam generated by the immersion heater, even if it were open, and the steam pressure could cause the cylinder to burst. Not likely, but possible.

Actually I have noticed that if you screw the cap all the way down and then have a shower, when you undo the cap afterwards loads of air escapes followed by a few hints of water then it cuts off. Presumably this is air from the tank that is getting cuaght due to the warix flange being the wrong way round.?

Probably, but you're assuming that it is a Warix flange and not a similar Surrey flange.

The domed top of the cylinder will funnel all the air bubbles to the top and the topmost connection must go to the open vent pipe and any gravity-fed taps. Both the Surrey & Warix flanges have a dip tube, which draws water from lower down the cylinder where there are few air bubbles. This connection must go to the pump.

If the connections are reversed, the air will be drawn into the pump and will get trapped at the eye of the pump's impeller, causing a drop in performance. When the pump stops, the bubbles will float back up the inlet pipe. This seems to be what you're getting, so my guess is that it is a Warix flange.

When opened why does it let air in when water is sucked down - is it a fualty vent i have or should automatic vents never be used on this type of set up becuase the pressure of the water being sucked out of the tank by the pump too much and causes the float to let air in whilst the pump is running?

It is working properly; it shouldn't be used here, or anywhere that a pump might cause sub-atmospheric pressures.

If I get the pipework swapped over would I still need a manual vent? How often are you supposed to bleed the air off?

Yes, you need one to release the air if you drain the pipes or disconnect the pump. There are usually inlet filters on the pump that need an occasional clean.

You shouldn't have to open it otherwise, no air should get drawn in. I'd open it after a week and if no air comes out, all is well. Then open it after a month or year or if the pump performance drops.

 

[mk2phil]

thanks for replying onetap.

The pipe coming out of the top of the pipe does indeed vent over the storage tank in the loft, the auto air vent that the previous owner fitted is just for the shower/pump piping.

Is there any way I can identify whether I do indeed have a Warix flange or surrey flange? Presumably a surrey flange has the dip-tube connection at the side as opposed to the warix which has the dip-tube connection at the top? I'd rather not start pulling it all to pieces only to find out it is actually a surrey flange and the connections are therefore correct as they are.

So it's possible that both the flange connections (assuming they're wrong) AND the auto vent are both introducing air into the pump?

Can you post a link to what sort of vent I should be using as I have no idea what it would look like. I assume I can just remove the auto vent and use this in its place without altering any pipework to it?

Thanks again mate

 

[Onetap]

Is there any way I can identify whether I do indeed have a Warix flange or surrey flange? Presumably a surrey flange has the dip-tube connection at the side as opposed to the warix which has the dip-tube connection at the top? I'd rather not start pulling it all to pieces only to find out it is actually a surrey flange and the connections are therefore correct as they are.

Pictures of the Warix and Surrey flanges here;
http://www.bes.ltd.uk/products/104.asp

The warix is a 2-part job, if I recall. The side connection is a separate part and is clamped onto the cylinder boss by tightening the top connection.

The Surrey flange is one piece, someone said; I've never fitted one.

Any maker's marks on it?

So it's possible that both the flange connections (assuming they're wrong) AND the auto vent are both introducing air into the pump?

Could be, a worst case scenario. The air vent might have been fitted to try to solve an air problem caused by the flange connctions having been reversed.

Can you post a link to what sort of vent I should be using as I have no idea what it would look like. I assume I can just remove the auto vent and use this in its place without altering any pipework to it?

Part 6793 or 9178 on Bes site above. You could just screw in a 1/2" ball valve to replace the AAV. The 15mm vents let the air out slowly and with an audible hiss, I find them less liable to suddenly spurt water.

 

[mk2phil]

Did some research before you replied and found the BES site. If I take the diagrams as gospel then I'd say I have a warix:

I take it a ball valve is the same sort of thing you'd find a washing machine water hose connected to..?

 

[andy72]

I've used these manual air vents on a number of pipes, with good results. They only open when you want them to, so no unexpected leaks, or air entry.

You can buy them from B&Q for a few quid, and they can then be soldered onto 22mm pipe. Don't take up much space either.

Andy

 

[Gasguru]

Use FULL bore isolating valves. Don't use gate valves (they don't always shut off fully) and don't use the non full bore valves as they are restrictive.

Remove the existing auto air vent and screw in a 1/2 inch radiator vent. These are operated with a normal radiator bleeding key. They won't block or leak as all the other types of vent do.

 

[Nige F]

That flange aint a Surrey ....maybe it`s a Sussex .....ok then , it`s a Warix