Trevi Boost - new installation not working - help!

[technogeek]

I've installed one of these before and it worked brilliantly, for many years. Now I've moved home and installed another - but simply can't get it working! The wife is threatening physical violence if it's not working soon!

I've spent some time optimising pipework to remove the possibility of airlocks, minimise bends etc, but it's had very little effect and I'm now stuck.

Here's some information:

Incoming cold water pressure = 2.8 Bar (measured using 2 different gauges, at the Washing Machine connection) I would expect the pressure at the shower, on the first floor, to be about 2.6 Bar.

Hot water head between the top of the water level in the cold water storage tank to the mid-line of the shower body =2m

Flow rate through the flushing nozzle on the hot outlet = 18L/min This is spot-on with the Trevi graphs and is as expected.

Hot temperature at flushing nozzle = 65C (measured using a calibrated electronic meter at the hot flushing outlet)

Flow rate through the flushing nozzle on the cold outlet = 40L/min (is this as expected for 2.6 Bar cold pressure?)

Flow rate through the shower head at normal showering height and fully cold = 13L/min (seems very low, almost marginal)

Flow rate and temperature at fully hot = 38C and 6L/min (both temperature and flow rate are too low)

The shower head and hose are the ones supplied with the Trevi Boost.

What I've tried:

22mm plumping and 22mm single check valves on both hot and cold

The shower take-off is now the first outlet on the rising main - and is 22mm throughout. The continuation run to the cold storage tank is run in 15mm

All plumbing re-routed to avoid any possibility of airlocks.

Replaced mains stopcock with 22mm full-bore ball valve

Re-plumbed between the incoming 25mm MPDE main cold water supply and the house stopcock with 22mm

Inspected the insides of the Trevi boost shower as best as possible for obstructions - none found.

Removed and replaced all connections to and from the Travi Boost to check for PTFE tape or other obstructions - none found.

Checked the supplied handset, flexible hose and all connections to the Trevi Boost for obstructions - none found

Removed the mixer cartidge and inspected the two strainers - both clean. Even tried temporarily removing the strainers completely - no effect.

Removed the over-temperature limiter completely - no effect.


Given the specifics of the installation, I would expect the shower to perform very well, but clearly something is wrong.

Possibilities:

1. A fault in the mixer cartridge ? Is this possible or likely?

2. Obstruction in cold feed between the airing cupboard and the en-suite - it's all 22mm as far as I can see, but presumeably this would be evidenced by a low flow from the cold flushing outlet - again is 40L/min as expected for a mains pressure of 2.6 Bar?

Unfortunately most plumbers have little or no knowledge or experience in dealing with venturi-effect shower boosters. I've asked a couple for advice, but they have not been exactly helpful! - Hence the posting to a wider, more experienced (?) forum...

I'd really like to get this working as I've owned one before, for several years and been very impressed with it's performance.

 

[Whitespirit66]

I have no experience of these showers. I think it would be a good idea if you expand (less than 1,000 words) on what way your shower is not working. Is there no flow through the main head, or is the flow inadequate?

Do the instructions tell you to fit check valves? Did you fit full flow c valves, as some can restrict flow, especially on gravity hot?

Try contacting the maufacturer, perhaps there is a fault.

 

[technogeek]

At 38C maximum temperature, it's too cold for a comfortable shower.
It's also a dribble.

Single 22mm full-flow check valves as per MI installed in hot and cold flows.

 

[Norcon]

Single 22mm full-flow check valves as per MI installed in hot and cold flows.

Are these spring loaded types? Do you have a spec for them?
Are they the same type of valve as used in your previous installation?
May be a high resistance to flow across the valve.
Not a problem for 2.6bar mains cold but gravity hot?

 

[technogeek]

The valves are as previously used. The hot flow has been measured and is 100% OK.

 

[seco services]

Sounds like a fault on the boost cartridge by what your describing.

 

[technogeek]

Mmm - a fault with the booster cartridge would be my final hope too. Seems unlikely though as it's a really simple piece of machined brass. Still, I've emailed Trevi all of my test results and now am waiting to see what opinion they have.

If they can refer me to an 'expert' plumber, I'd be happy enough to pay!

I decided to install a Trevi Boost after my old shower pump a QT, decided to start screaming after a few minutes of showering. The pump is only a couple of years old. QT were pretty unhelpful after they realised that it was installed exactly as per MI's

 

[UpgradeME]

Hot temperature at flushing nozzle = 65C (measured using a calibrated electronic meter at the hot flushing outlet)

Taken from the Trevi Boost TS22 Installation manual:

This device uses a thermal element which reacts to over-temperature water, pushing a valve on to the seat at the bottom of the booster cartridge.

In the event of a cold water failure this valve element reduces the output flow of the Trevi Boost to a trickle if the water exceeds 45C.

Perhaps try lowering your DHW temperature down from 65C (which seems high to me!?)

It also says:

If direct mains cold water pressure is greater than 3.0 bar, a pressure reducing valve must be fitted. If input conditions are minimal, then mixed shower temperature may only read 40C

(The 40C being your symptoms...)

 

[Googlyhead]

Taken from the Trevi Boost TS22 Installation manual:

This device uses a thermal element which reacts to over-temperature water, pushing a valve on to the seat at the bottom of the booster cartridge.

In the event of a cold water failure this valve element reduces the output flow of the Trevi Boost to a trickle if the water exceeds 45C.

The original post said the over temp device has been defeated to eliminate the possibility of a (common) fault in that. Looking at the functional diagram; this only reacts to the temperature of the mixed water: So for it to act, there has to be either a fault, or more hot than cold flowing through to it (fault elsewhere).

The only ideas I have (simply through looking up the Venturi stuff out of interest!) are;
Plumbed in the right-way-round? (obvious, I know! But possible connections are different to your old one dependant on make, age, recessed or not etc.)
Can the Venturi cartridge be back flushed or something? Just to eliminate the possibility of any non-visible debris?

I don't see the actual flow rate of cold supply causing a problem with the output flow rate; just possibly the degree of control you have being affected if the cold pressure/volume is significantly high.

Look like a nice idea, these showers! Not for me, as I have mains hot, but good alternative to a pump!

 

[pampers]

if i rember correctly there is a part in the manual/install instructions where it mentions switching out the thermostatic cartridge for a manual cartridge to gain a higher temp shower if there is problems.

 

[technogeek]

I tried removing the overtemperature cut-out (as Googlyhead states - this only shuts the flow off if the blended temperature exceeds 45C) but there was no effect.

Definately plumbed in the right way round as per MI and also agrees with the "HOT" and "COLD" cast into the shower body. (Nice touch, Trevi!)

The incoming mains pressure is approx 2.6 Bar, so it good, according to the MI

I do like the idea of back-flushing the Venturi - this is easy to do once it's removed from the valve body. Nice suggestion Googlyhead.

Still no reply from Trevi - I hope they're thinking about it!

 

[technogeek]

Mmm - Trevi responded.

They reckon that the problem is that the cold is plumbed with 22mm and not 15mm.

Not sure why this would affect the shower. 15mm would affect flow pressure and flow rate, but this would be dependent on the length of 15mm pipe and number of bends.

I have 17m of 22mm connecting to the 25mm MDPE incoming main feeder.

This is probably equivalent to 10m of 15mm in terms of pressure drop.

Also, at one stage I did have it plumbed in with 7m of 15mm followed by 10m of 22mm and that didn't work either.

I really don't want to rip up the house to install 15mm throughout and have it still not work.

Stumped.....

 

[Norcon]

Fit a proper shower like a mira excel fed from uv cylinder and quit futering with that heap of junk.

 

[dreadnoughtheating]

Fit a proper shower like a mira excel fed from uv cylinder and quit futering with that heap of junk.

To be fair to the trevi, have fitted a couple and punters have been well pleased.
I gave up the will to live half way thro' the list of just how good this install is,
But, once had a poor performer (installed by A.N Other), took off head, layed hose on shower tray, open hot only, out poured loads of air, and Hey-Presto another satisified customer?

Just a thought

DH

Oh, and I think the NewTeam version is MUCH prettier. LOL

 

[technogeek]

I reckon that it should work - IT WILL NOT BEAT ME

Already tried removing the outlet hose and blasting water through (and even re-routing the outlet pipe so no airlock was possible... but no joy.

Also tried removing the mixer cartridge and reverse flushing it as suggested by Googlyhead- no change.

Might try taking the mixer cartidge apart tomorrow.

Gettin' desperate now....