any plumbers in? « Singletrack Forum

Chat Forum

[closed]

any plumbers in?

13 posts & 5 voices | Started 1 year ago by mrmichaelwright | Latest reply from mrmichaelwright

Tags:

No tags yet.

mrmichaelwright - Member

Got an on going problem with our shower, on our third pump now.

system is:

boiler in loft, gravity fed hot water tank fed from twin tanks in loft.

shower is fed by direct supply from slave tank in loft and a warwick flange on the HW tank. The pipework is 22mm as far as the pump and there are no inverted loops. The pump supplies only the shower and is not tee'd off to anything else.

The pump is a Salamander RHP50 and we've had the manufacturers out to inspect the installation, they are happy with the system and replaced the (1 month old) pump under warranty.

Problem is air getting into the pump from the HW tank despite the correct installation of the flange. When the shower is switched on you can hear air in the pipework near the HW tank (pump is under bath). As the air hits the pump it causes it to make nasty noises and this is causing the bearings to fail (i reckon anyway).

My question is this, where is the air coming from? as far as i can see the venting is correct on the HW tank and i can't really see how a warwick flange could fail.

I'm pulling my hair out here, our plumber who moved the boiler and corrected all the screw ups by previous installer is also at a loss.

HELP!

Posted 1 year ago #
5lab - Member

have you looked in the tank as water is being pulled? maybe the suction force is disturbing the water in the tank causing air to get sucked in instead of air

Posted 1 year ago #
mrmichaelwright - Member

thanks, originally that was a problem, the outlet was too close to the inlet but now the outlet is in the slave tank and correctly positioned.

I've just whipped out the Warwick flange and there was a hell of a lot of calcification on the HW/vent output inside, i've cleaned this off to see if this is maybe causing a blockage stopping the air escaping. My local plumbers supplier doesn't stock warwick flanges and i'm loathe to order online as there are variations on the one i need that i don't quite understand without seeing them in the flesh!

Is it possible that the excess air is caused by having the boiler temp set to high? The plumber commissioned it with the boiler output set to max and said to leave it there as we have thermostatic valves as well as a room stat. Could very high temperatures in the heat exchanger cause the water to boil slightly around the pipes? Tank thermostat is set to 50 (checked at tap with thermometer)

Posted 1 year ago #
sprooty - Member

Hi

Long time lurker, just registered to reply:

Had the same problem (without the Warwick flange), was an airlock in the pipe from the cold water tank in the loft to the hot water cylinder. The pump sucks out from the cylinder faster than it can be replaced from the header tank, this causes the pressure to drop, and hence the water level to fall, in the hot water vent pipe, the top of which is open to air. This is where the air was coming from, it has to come from somewhere after all

You can fix it by fitting a restrictor on your shower head, reducing the flow from the cylinder, or fixing the feed pipe from the header tank (bigger bore or removing any potential restrictions, airlocks etc).

You can also prove if this is the problem by removing vent pipe from the cylinder when the shower's running, if it's dry that's the issue, normally it would have water in it. This was easy for me, all my plumbing is speedfit, if yours is copper it's not so easy!

Posted 1 year ago #
mrmichaelwright - Member

thanks sprooty and welcome.

It's all copper and i'm pretty sure the vent pipe is wet but i could always pop it off with the shower running to see if it's dry or drawing in air. The only thing to suggest otherwise is that it is worse when left overnight, if it was drawing in air whilst running i'd guess that that air would dissipate overnight rather than build up?

just off to burn my hands again then

here's a pic of a manky flange to keep you occupied

24/02/2011 by mrmichaelwright, on Flickr

Posted 1 year ago #
mrmichaelwright - Member

vent pipe is full of hot squirty water

Posted 1 year ago #
davesmate - Member

Get rid of the Warwick flange and take your hot water feed by teeing from the underside of the horizontal pipe coming from the top of your HW cylinder. This should reduce the chances of pulling in air.

Posted 1 year ago #
mrmichaelwright - Member

hmmm

there's no horizontal pipe from the top of the cylinder, the shower is from the top output of the flange and the taps are supplied by the side output of the flange which is tee'd off to the vent.

like this:

Posted 1 year ago #
tomlevell - Member

You should have a separate cold water feed from the cold water tank also. It shouldn't be off the tank water supplying anything else although the same tank can have another connection for elsewhere.

As said above try the other setup off the top of the cylinder. Should be in the manual. Come off at 45degrees and tee off this on the underside for the shower only. Everything else fed from the top and the air should go that way.

Although IMO rip it out and either fit a electric shower or a Combi or a mains pressure cylinder. Shower pumps will only ever give you grief.

Posted 1 year ago #
mrmichaelwright - Member

thanks tom, how's you?

not going to replace boiler, it's only 2 weeks old! There is a dedicated supply from the slave cold water tank as i said.

if cleaning the flange has made no difference then I'll have to get the plumber back in to do as suggested, getting to be an expensive shower now! (we got rid of electric shower when we moved in, can't stand them)

Posted 1 year ago #
sprooty - Member

Thanks MrWright

If there's no air in the vent pipe @ cylinder level another possibility is that there's not actually any air in the pump at all (where would it come from?) but that the pump is cavitating, which would suggest that there isn't enough flow from the cylinder/tank to satisfy it. Likeliest suspect is the hot, and if this is the case the warwick flange is probably the culprit, particularly if it was scaled up as in your piccy.

Maybe try it without? It's only to stop air being drawn in from the vent after all, and you confirmed there wasn't any.

Again, reducing the flow from the shower will also help.

Posted 1 year ago #
davesmate - Member

there's no horizontal pipe from the top of the cylinder, the shower is from the top output of the flange and the taps are supplied by the side output of the flange which is tee'd off to the vent

replace the warwick flange (we call it a Surrey flange round here) with a standard single outlet flange to the pipe supplying water to the hot taps

Posted 1 year ago #
mrmichaelwright - Member

right, having cleaned the flange up things are looking good but i'm not 100% happy. I've ordered a new flange manufactured by the people who make the pump. If this doesn't work then i'll get a refund on the pump and get the plumber to fit one he approves of and then it's his responsibility to get it working.

I can't really try the shower without the current flange as i'd have to jury rig some kind of temporary flange which is just going to end up with me having to paint the damp patches on the kitchen ceiling again.

Posted 1 year ago #