New thermostatic shower - only warm with low flow

[Rimrogs]

Moved into a new house and ripped out cheap suite in downstairs bathroom. Fitted thermostatic Triton Antares mixer shower on gravity fed system. Before plastering/tiling, I tested installation. The flow is poor and cool. The shower head is a flat 'disc' type fed by 15mm pipe. The H&C pipes are 15mm too. Cold water tank is in loft (3m above shower head) and cylinder is middle floor. Hot pipe feels hot at mixer but still cool emerging. I guess cold water pressure is preventing hot from flowing. Will it help to fit 22mm pipe at outlet of mixer for more flow? Do I have to repipe in 22mm?(mammoth job). Will fitting a pressure reducer to the cold inlet help? Or do I have to fork out for a pump?
Any advice really welcome
Thanks

 

[JohnD]

You mean the cold supply comes from cold tank (not mains pressure) and so does the hot? But the hot pipe feels cool?

Silly question - you have got the hot and cold inlets the right way round (can confuse a thermo shower if not) and therw isn't a preset on the mixer that stops it getting very hot (one of my mixers has this to protect children from scalds)

And it has a good big shower head that gives a good flow?

Service valves fully open (you could try half-closing the cold one as an experiment)

If the cold is mains fed and the hot is tank fed, you need a pressure reducing or equalising valve.

 

[Rimrogs]

Hi JohnD
Cold water is fed from tank in loft. Hot (I think but not absolutely sure) is also fed from tank.
H&C are both correct and control knob working ok.
It does have a big head but not good flow!
Will try reducing cold pressure tomorrow and will post results if you care to look again.

 

[JohnD]

OK. a useful trial - set it to "hot only" and to "cold only" and in each case put a bucket under the hose and see how many litres per minute you get (with the spray head removed). This will tell us the maximum flow available. It might be that you need a pump though 3metres head sounds fair (I have 9metres head due to tall house!!)

If you have e.g. a cloakroom basin nearby, try the flow rate on any other taps. Also get an idea for the pipe runs - mostly straight, or lots of elbows? If you have those little service valves with a rotating ball inside, they have a narrow restriction in the ball.

there will doubtless be someone along with more experience of your particular problem once we figure out what it is

 

[Rimrogs]

Tried hot only/cold only - got over 7 litres/min cold and around 3 litres/min hot. Not good is it?
Three elbows that I can see and logically a pipe run of around 10m.
Am trying to work out the pipe installation but there seem to be pipes everywhere

 

[JohnD]

You might want to re-check that the cold is from the tank not the main (ground floor in my house has mains cold)

After that, I'm stumped and will stand aside for someone cleverer.

 

[Rimrogs]

Cold is definitely from tank in loft.
I suppose it's a pump or bigger feed (I have to find the pipes first !!)

Thanks for your help JohnD

Any other suggestions welcome !!

 

[bpowell555]

I fitted a tank fed thermostatic shower earilier this year. The pipes are 22mm however although I ran 15mm off them. Because of the tank layout I should have the same gravity pressure as you although the 15mil pipework could be reducing flow I guess.

In short the shower is bl**dy brilliant and I love it. If with hot only you're still getting no pressure then maybe it is because of the 15mm pipes? Or is there a pressure reducer in the mixer you could remove?

Sorry I can't be more help

 

[Rimrogs]

After discovering that I could only get 3 ltrs/min hot water - I've concluded there must be some restriction in the pipework somewhere. I don't know if I'm correct in saying this but I think 7 l/m should be enough for a shower?
As I said in my earlier posting, I'll have to trace the route of the pipes (floorboards up/chiselling out walls etc) and find the restriction and then either put in 22mm or fit a pump. So much for a straight-forward job !!
Thanks for your thoughts anyway

 

[Expertboy]

Bet this system has never been brilliant since first being fitted. I always run 22mm throught he loft and drop down in 15mm (except on electric showers with 40amp breaker). no matter how long the pipe run and never had a problem.

 

[Rimrogs]

Right - slight progress....hot water emerges from tank in 3/4" pipe. This expands to 1" for a couple of metres under the floor when it then splits into 1/2" for the upstairs bathroom tap & 3/4" for the drop downstairs. It is then reduced to 15mm about 3m from the new shower location.
Disconnected feed pipe at floor level & pressure/flow seem really good. Connect back to the shower mixer and result is poor flow and pressure again. Cold follows exact route and pipe size changes but is good at the shower head.
Removed valve filter and blew through the 2m to the shower head - seems clear.
My thoughts are that the mixer itself is affecting the flow/pressure - is this possible?
Still stumped as to why the pressure should be so good at floor level and so poor at the head if both hot and cold are tank fed and follow the same path? This means that flow (volume isn't the problem??).
Becoming really stuck & frustrated now....help please !!!!!

 

[Bas]

Someone mentioned it before but is there a service valve anywhere. If there is check the type - if its the type you need a screwdriver to operate it will be restricting the flow significantly. Get a full bore one.

 

[Rimrogs]

No service valves anywhere as I've only just put it in & can see almost all the pipework now.
Hate to admit defeat but will have to call a plumber soon

 

[Rimrogs]

Poor hot water flow - 4 l/m (cold 7+ l/m)...with 6" fixed sprayhead
removed. Pressure of hot 0.3 bar at rose connection (cold 0.42 bar)

H & C pipes run same route, same sizes, same amount of elbows etc
No service valves in hot supply (1 in cold)
Both supply pipes are approx 8m @ 22mm and last 5m @ 15mm
Bypassed mixer & obtained 7 l/m flow from hot supply pipe (is mixer restricting hot?)
Filters swapped but no change
Strangely, Triton booklet specifies 3/4" to 22 or 15mm fittings. I could only fit 1/2"BSP to 15mm as 3/4" would not fit valve body as far too big.
Is there any other way of proving mixer valve?
Triton helpline advised calling their service engineer (great response!)
Do I really need a pump? This is my last chance before radical steps !!
Any suggestions welcome