Trevi Boost - new installation not working - help!

[sooey]

Can't you fettle a length of garden hose to feed the cold temporarily, just to try it.

 

[technogeek]

I asked Trevi to explain why they thought 15mm to the cold inlet would work when 22mm would not - their reply was "read the F***ing manual"

Might have to try it after all.....

 

[technogeek]

I had a discussion at work with one of the egg-heads of our mechanical engineering department and his conclusion was that it would make bugger-all difference to run a 15mm feed to the unit.

However, Sooey is spot on - 15mm garden hose to the outside tap and let's see what happens.

I'll eat my hat if it works....happily!

 

[ljmountain]

Technogeek: Did you find a resolution. I am experiencing similar issues. The only thing left for me is dismantling the boost cartridge.

I am working through the diagnosis stages (all MI instructions followed to the letter).

The incoming cold water feed is 2 bar, when tested just before entering the trevi valve it is 14 litres per minute (tested through the shower head screwed onto the valve body). If I run a Full Rate Cold Water test via the mix exit using the same technique then the flow rate is 8 litres per minute i.e. I appear to loose 6 litres per minute flow rate when going through the valve! The MI instructions advise this test should be more like 14 litres per minute which implies minimal lose! I have cleaned everything possible to clean and wonder if a faulty boost cartridge.

 

[DeltaT2]

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...)

I think this guy is on the money & your cold mains water pressure is borderline & your Hot may be too hot at 65C. It may need a pressure reducing valve?? Not sure why you increased the pipe size on the cold too 22mm???

 

[technogeek]

Technogeek: Did you find a resolution. I am experiencing similar issues. The only thing left for me is dismantling the boost cartridge.

I am working through the diagnosis stages (all MI instructions followed to the letter).

The incoming cold water feed is 2 bar, when tested just before entering the trevi valve it is 14 litres per minute (tested through the shower head screwed onto the valve body). If I run a Full Rate Cold Water test via the mix exit using the same technique then the flow rate is 8 litres per minute i.e. I appear to loose 6 litres per minute flow rate when going through the valve! The MI instructions advise this test should be more like 14 litres per minute which implies minimal lose! I have cleaned everything possible to clean and wonder if a faulty boost cartridge.

Well, to their credit, Trevi did eventually send an engineer to have a look. He spent about 4 hours with me, during which time I completely re-plumbed the cold in 15mm (thank god B&Q are close and PolyPlumb is quick to use!), removed both single check valves on hot and cold and tried several other things.

In the end he left, muttering ' buggered if I know' and Trevi sent me a complete replacement unit - which still didn't work.

I then had a new boiler fitted and the plumber for that job fitted a pressurised system. (so hot and cold now at the same, mains pressure) I contacted Trevi again (now on first-name terms with Terri at Trevi!) and they sent me (free) a Trevi Boost to Trevi Therm conversion kit. This kit converts the shower into a standard thermostatic mixer shower for high-pressure balanced hot and cold feed systems.

Now, after 6 months, I have a fully working shower and the wife is happy... The shower is absolutely excellent and I'm very happy with it. Pity that I had to get a fully pressurised system installed, but there you go.

Now despite all of this hassle and grief, I am still a happy customer. I am absolutely amazed with the support that I've had from Trevi and their products (when they work) are superb. Really can't complain.

I'm sure that there's got to be a rational reason for the failure of the Trevi Boost but it must be a complex and subtle one for it to baffle Trevi themselves.

The only one remaining thing that I could think of that I never tried was to try running the mixed water outlet to the hose connection in 22mm. It would only be a short length (about 2 feet in my shower) but I had a theory about back pressure at the interface between the shower body and the 15mm mixed water outlet causing the problem. When the shower head was removed, the flow rate shot up and so did the temperature. Anyway, probably complete *******s, but it may be worth a try.

I'd be really interested if you find out what caused the problem in your case, but if you really have absolutely installed as per MI, then give Trevi a bell and ask for an engineer to visit. It may take a couple of weeks, but if you can wait for it, then you might get it solved.

Good luck!

 

[DeltaT2]

Glad you got sorted mate, well at least in some way sorted. Fitted a few Trevi Boost & have always found they need to be text book installs, nut great showers.

 

[technogeek]

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...)

I think this guy is on the money & your cold mains water pressure is borderline & your Hot may be too hot at 65C. It may need a pressure reducing valve?? Not sure why you increased the pipe size on the cold too 22mm???

You haven't quite got it right. The hot temperature INLET is 65C and that's fine. The thermal element only shuts the water off if the MIXED water temperature exceeds 45C and this would only happen if the cold water ceased. (The thermal element is a wax-filled capsule that sits in the mixer outlet flow - I tried removing this as well, but the effect was tiny)

My mixed water temperature never got near 45C and the flow was not a trickle, it was far more than that, but still much less than the graphs predicted.


We tried reducing the hot water inlet temperature and guess what.. the mixed outlet temperature reduced as well....!

Regarding the pressure, when the Trevi engineer was on site, we did try reducing the cold pressure down to 2 bar with no effect.

In the end, after 4 hours of frantically trying pretty much everything, the Trevi engineer left, shaking his head...

 

[DeltaT2]

Chasing Moonbeams mate, chasing Moonbeams. With the Laws of Physics there's always a reason it'll not work......We both don't know why but someone would. Many, many times I've been chasing moonbeams in the Plumbing trade & many, many times I've not seen the wood for the trees. But I love my trade, always a challange.

 

[ljmountain]

I opened a call with Trevi yesterday and they are organising an engineer to come onsite already. I did write an huge email with the results of all the tests as per the instructions so I think that might be why they are moving quickly. The response from technogeek has given me another avenue though. The 15mm cold feed is only 15mm for about 2m before the Trevi boost, before this it is 22mm and a reducer is fitted (in fact it is a tee- 22 in, 22 to cold water bath and 15 onwards to Trevi). I cannot get my head around the fluid dynamics but maybe this is important (can anyone explain?). It does not say in the MI about how long the 15mm cold feed must be before entering the valve but something is nagging me from my physics lessons 20 years ago about fluid dynamics and that maybe a certain length of pipe is needed after the reducer. I just assumed probably wrongly that a 15mm cold feed was needed to reduce the flow per litre (perhaps this is basic plumbing rules which I am missing). Another consideration is that the 15mm after the Trevi continues to the hot water header tank, when running tests for Trevi though several of the test involved turning off the hot water isolation valve to make sure that pressure/flow was not being affected by replacing water to the header tank. I woke up thinking about this hence the early morning post!!!

 

[technogeek]

Chasing Moonbeams mate, chasing Moonbeams. With the Laws of Physics there's always a reason it'll not work......We both don't know why but someone would. Many, many times I've been chasing moonbeams in the Plumbing trade & many, many times I've not seen the wood for the trees. But I love my trade, always a challange.

I couldn't agree more! - there must be a rational explanation. I'm a professional engineer and it's the satisfaction of solving enginering probems that has kept me enthusiastic about my work for the last 27 years!

 

[technogeek]

I cannot get my head around the fluid dynamics but maybe this is important (can anyone explain?).

The fluid velocity wil be higher than in 22mm for a given pressure and flow rate, but how long the 15mm needs to be, and why fluid velocity could be important beats me!