Venturi Shower Trevi Boost

[johnny avocado]

Hope you chaps are getting on fine now!

Im going to spend a bit of time over the weekend trying to get the Trevi to work.

A couple of potential issues might be;

I have 22mm check valves on hot and cold. I bought these asking for 22mm check valves, what if I have installed double check valves instead of single. Small brass screw mid body of valve, small white plastic ball at one end, plastic grille at other. Does that sound like a double or single valve?

Would a double give the symptoms referred to?


Also connection from mixer to handset 15mm flexible. tightish radius off copper fitting to reach handset.

JA

 

[Balenza]

I stand humbly corrected - it turns out that you're more stupid than I thought possible.

Who corrected you ?. That probably happens quite frequent for someone like you anyway.
I think your butt is full of pushfit grab rings. Hence the reason why you cant pull your head out.

 

[Balenza]

johnny avocado

what if I have installed double check valves instead of single.

Then the restriction and pressure drop across the valve is at least doubled in comparison to a spring loaded nrv.

Small brass screw mid body of valve, small white plastic ball at one end, plastic grille at other. Does that sound like a double or single valve?

Its a double check valve alright. The brass screw in the middle is a test cock to verify if one check has failed.

Im hoping to install one in a few weeks time Johnny when my supplier eventually realises that Trevi have not stopped manufacturing them.
As I stated earlier I dont see the need for nrv,s on the hot supply and dont intend fitting one.
My advice to you is get rid of the DCV and fit a Swing Check valve in your hot supply and be careful with the orientatation of this particular valve.
Have you tried turning the mains cold off and turning on the hot supply only to see what flow you get through the valve ??

 

[Softus]

Im going to spend a bit of time over the weekend trying to get the Trevi to work.

The best possible first step you can take is to ignore anyone who advocates not following the manufacturer's installation instructions.

The purpose of the NRV on the hot service is to prevent a shower valve failure resulting in cold mains being fed back to the hot service.

If you've fitted a DCV then exchange it for a single, and make sure you get a full bore check valve so that it's as unrestricted as possible. Full bore ones aren't always easy to come by, hence I stock at least four so that I have a buffer before having to phone around for more.

Once you've installed it as per Trevi's instructions, if it doesn't work then you can call them in the knowledge that they'll start to help instead of telling you to go away and read the manual.

 

[Balenza]

Softus wrote

resulting in cold mains being fed back to the hot service.

Which can lead to ????

and make sure you get a full bore check valve

Are you not aware of a swing type check valve designed for low pressure installations ?.
Do you always advocate complying with MI,s even when their is a better solution on the market ?

 

[Softus]

Balenza, if you really think that you can hurl insults at one moment and seek answers to technical questions the next, then your understanding of human nature is rather poor.

 

[Balenza]

Softus wrote

then your understanding of human nature is rather poor.

Your understanding of plumbing systems is rather poor buddy.

And anyway regarding hurling insults what do you call this ?

it turns out that you're more stupid than I thought possible

 

[Softus]

OK - you win. I give in.

You're more intelligent than I am, wiser, better informed, have a greater vocabulary, more technical and practical knowledge, more empathy with novice members, and you're generally an all-round better human being. Congratulations.

Oh, and your personal hygiene is beyond reproach.

Now that we've got that sorted out, I need never respond to one of your posts, or recognise your existence, ever again. Nor you mine.

Ever.

 

[johnny avocado]

Guys, thanks for your help.

I will try the least restrictive single check valve I can get my hands on.

When I run the hot only, with the cold stopcock off, the hot runs for about 20 secs, then runs down to a trickle, then stops. I did think it might be the trevi hot cut off valve, but the water isnt excessively hot when this happens.

JA

 

[Softus]

I did think it might be the trevi hot cut off valve, but the water isnt excessively hot when this happens.

johnny, if you run the valve without any cold supply then surely the temperature will be in the region of 55-60°C, which would be excessively hot.

 

[Balenza]

johnny avocado

I will try the least restrictive single check valve I can get my hands on.

This is your best option.
http://www.tpub.com/content/doe/h1018v2/css/h1018v2_55.htm
Most plumbing suppliers should have this valve in stock.

Softus wrote

johnny, if you run the valve without any cold supply then surely the temperature will be in the region of 55-60°C, which would be excessively hot.

Their is what sounds to be a DCV installed in the hot flow to the Trevi Boost.
These valves will create a huge resistance fitted to a gravity fed system.

 

[johnny avocado]

I install a more appropriate valve over the weekend and post what happens.

Try and get along guys, I do appreciate your advice, we'll see what works!!

JA

 

[chrishutt]

Johny, try it without a check valve of any sort in the hot supply first just to see if it then works. If it does, you know you need a very low resistance check valve (a swing type, mounted horizontally). If it doesn't, you know there's some other problem.

 

[johnny avocado]

Thanks for the advice.

Tried hot without valve and no real difference.

Decided to go back to basics and check pressure and flow rates.

Mains pressure was 3.5bar, up from my last reading and now over the MI recommendations.

Flow rate was 12l/m on the hot at shower head level, this corresponded to the MI estimate for 1m head. The head I have is about 1.75m so allowing for losses this checked out ok. However the flow rate on the cold was enormous, 60l/m well outwith the MI value of about 20-25 for 3 bar.

Throttling back on the cold stopcock gave me a hot shower, roadtested by the missus with an acceptable flow rate, measured at about 6 to 7l/m.

I think the problem is over pressure on the cold and consequent high flow, if I affect the cold rate by the stopcock it works just about ok and acceptable for a reasonable shower probably better than a good electric one.

I suppose a pressure reducing valve would help on the cold, but I fear that even then the performance wont be much better, Trevi indicate terget flow rates of about 8l/m.

I think I might have been expecting too much in terms of flow rate.

I need to renew and relocate my hot water cylinder in thenext couple of months. I might try reducing the length of hot pipework and maybe get a low pressure pump to take the household hot up to about 0.3 barwhich would improve the sytem.

But the shower will be good enough for the next few months.

Cheers again

JA

 

[Balenza]

Johnny avocado wrote

When I run the hot only, with the cold stopcock off, the hot runs for about 20 secs, then runs down to a trickle, then stops.

Then he wrote

Tried hot without valve and no real difference.

Then he wrote

Decided to go back to basics and check pressure and flow rates.

Flow rate was 12l/m on the hot at shower head level

So with the DCV fitted the hot flow reduces to a dribble and without the DCV fitted you acheive 12L/min.
Correct me if I am wrong but that seems like quite a difference.