Low shower pressure

[Gozoman]

Really need some help with this. I have a Triton LP thermostatic shower mixer valve. It is a simple gravity feed system with the cold and hot feeds coming from the loft directly above the bathroom. The cold water tank is situated in the loft and the hot water cylinder is situated in the airing cupboard in the bathroom with the hot feed going up into the loft across and down to the shower.

The problem is pressure. It has never been a power shower obviously but there was a decent enough pressure to have a shower, then it started to play up. When I turn it on with the thermostatic lever set to where it would normally be the pressure seems okay but then after about half a minute you can see the pressure dropping off. If I turn the thermostatic control to full cold the pressure goes back to normal, if I turn it to full hot it drops back to practically zero.

What I have done so far is the following. I have isolated the supplies and taken the valve off the wall. I have turned on the cold water and let it run for 10 minutes to clear the line. Did the same with the hot supply. I have run a hose up from the mains tap in the yard and connected up to each pipe in turn and used the mains pressure to blast the lines back to the cold tank. I have stripped the thermostatic valve completly and cleaned out the filters on both hot and cold inlets as well as flushing out the rest of the valve. It is a low pressure valve so there is no reducer fitted.

And that's it. I don't know what else to do. I thought it may be an air lock on the hot side but given that the hot water cylinder is fed from the bottom with the outlet at the top I can't see how that could be. Any ideas would be greatly appreciated as it's driving me nuts!

 

[SlowDrip]

Hrm, sounds like the cartridge valve may be faulty. As i recall the Triton units have a relatively weak little doohickey (that is the technical term, of course) that shifts the mixing knob. A replacement cartridge will probably do the trick.

 

[Gozoman]

What exactly is the 'cartridge' mate? Is it the complete unit basically? Any idea what a new one would cost? I just get the idea here that I could spend a lot of money on this cartridge thingy and end up with the same problem.

 

[Gozoman]

I've just been looking online and I can get a brand new cartridge minus the brass housing for £95. I don't mind the £95 but I hate the thought of spending that amount of money and finding that it hasn't made any difference to the situation. Any thoughts on how likely it is that the cartridge is indeed causing the drop in pressure on the hot side?

 

[SlowDrip]

Well, it is impossible to be certain without being there. I would first try stripping the unit down and cleaning everything to make sure it isn't just a chunk of scale blocking the flow. Unlikely, but possible.


Wait...£95?? Is this thing made of solid gold or something? For that kind of cash you can get a brand new mid-ranged shower unit.

 

[SlowDrip]

Did a bit of internet digging since Triton isn't a brand I am familiar with at all. Apparently this is a common problem that they have, and the cartridge is indeed around £95 for some insane reason.

Before you go out and buy the execs at Triton a new sports car though, you can try cleaning out the check valve which apparently also has some issues. See page 20 of this PDF for instructions.

http://www.tritonshowers.co.uk/media/8739/lp_exposed_with_riser_rail.pdf

 

[havasu]

SlowDrip...that is some great information. Thanks for taking the time to research this!

 

[Gozoman]

Thanks a lot SlowDrip. Actually I have already stripped this unit down several times and cleaned the check valves in both the hot and cold feeds which are contained in the elbow joints. The first time I did this there was indeed a blockage in one of the check valves caused by someone not doing their job right. Whoever installed the cold water storage tank in the loft which is a plastic one drilled out all the holes for the inlets and outlets but then didn't bother cleaning the tank out. I found several little bits of black plastic which were preventing the check valve from operating properly. However since I did this it has not happened again as I've had them out several times since to check.

As you say £95 does seem quite a lot to pay for this but basically what you are getting is everything in the diagram apart from the brass housing numbered 3 and all the bits which connect to it such as the elbows etc. If you think £95 is bad you want to try buying one from Triton themselves!