shower hot water low pressure only (now fixed)

[fuzzyone]

Hi guys,

hopefully its a straight forward fix, I have a triton mixer shower, recently ive noticed that the pressure is not that great, it was fine before not powerful but good for a decent wash.

I have the traditional water tank in the loft and cylinder in the airing cupboard setup, unvented i think it called?

I dont think its my Mira response shower head, the shower head is held about head height and there is a 1.2m hose with 11mm bore connected, now if i lower this down it starts to regain its pressure, if i lift it as high as i can it trickles. It use to work when lifted high up, never trickles.

What could it be? air in the system? the actual mixer/cartridge? Only lived in the house for a year and those were all new when I changed them. I will clean the shower head but i dont think its that as the pressure returns when lowering the showerhead, Ive not noticed anything else and no house work was done.

Also when this happens i've notice it splutters a little somethings, not a constant flow, when the shower is often, it often leaks for another few mins and sometimes randomly the water drips from the shower head then stops.

I'm not a pro on plumbing but can follow instructions

 

[fuzzyone]

Just to update, its a vented gravity fed system.

The shower cartridge has been replaced and seems to be a bit better but at times it can be worst which i'm starting to think its something to do with the pipes or tanks?

I drained the pipe which feds the hot water cylinder, did hear some air sound but when i open the valve more it goes away and seems to only make the sound if its slightly open. So i think this isnt actually doing anything.

There is a gate valve which seems to take longer to open and close, it leaked at some point but fixed it by tightening the nipple bit.

There is another valve above the hot water cylinder but i think this is to stop hot water going downstairs.

Could it be air / airlock / faulty gate valve etc?

Is there anything I can try before I start replacing unecesary bits n bobs?

 

[kbdiy]

Could it be hard water scale in the shower head itself? It's something we suffer with here too. Occassional descaling of the head fixes it.

 

[fuzzyone]

I thought that as well, no i havent descaled it however I dont think its that because if i hold the hose lower than head height the flowrate is alot better, if i put it back to headheight again it turns into a dribble, if i wait approx 20 secs it will start to return to poor flow than dribble.

Cold water is good, hot water use to be similar to cold water flow rate.

I know the flow rate is not of a proper pressure but it was good enough to have a decent shower. Oddly, every now and then the hot water flowrate seems to return near to how it was but then next day its back to a dribble every now and then

 

[fuzzyone]

I'm now starting to think it might be that gate valve that feeds into the hot water cylinder.

Let me run this by you guys, when i run the shower, its at poor flow, if i lower the shower head the rate is better but once i lift it up to headheight again the flow becomes a fast dribble which slowly returns to a poor flow rate within 20 secs.

If the gate valve is faulty (possible half open or not fully open) the refill of water lags which is what I see from the flow rate improving from a dribble to poor?

In theory its not possible to have air in the system as its a vented setup?

 

[fuzzyone]

thought i'd update this.

Seems somehow there was air along the system, not sure if the shower itself caused it but its now fixed.

All i did was let the shower head hang on the floor and let the water flow, i soon started to hear air coming out, took about 5mins to clean and the pressure seems to be back to normal.

Not sure if it was other things i did but its now working so....yay lol

 

[Hugh Jaleak]

I've got a Triton mixer with similar problems that I cant get my head round, my plumbing logic says it can't get air in the pipework, but it does..... Cold supply seems fine, hot air locks if a bath is drawn off. Odd....

 

[goateater]

I've a simaler probelm
last year i replaced and rerouted lots of my water pipes,
since then the flow in the hot water pipe to the bathroom always gets air trapped in ti
tried lots of things to get rid of air
I now think the probelm is due to the immersion tank not filling quick enough, so as I'm drawning off hot water the level drops below top of the immersion tank air is drawn in from the hot water expansion pipe

so i'm looking to change some (not all) of the inlet pipe from 22mm to 28 mm, to give a better flow on inlet side of immersion tank

what do you think