Trevi shower stopped working

[Roger]

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The only other thing I can think of is for you to increase the hot water pressure by raising the cold water tank but that may not be practical and I have no idea how much extra head would be required to make a significant difference.

[treenoakio]

Measuring from the surface of the water in the tank to the mixer unit it's just under 2M. The shower is said to work with negative head, so around 2M head (as defined in the Installation guide) doesn't seem too disadvantageous. It's a shallow roofspace too, so not a lot of leeway there. I could maybe squeeze some extra head by bending the arm of the ballcock, but I already did that once, so not a tremendous amount left there. I'd rather attempt remedies which don't involve using electrical boosting but I seem to be running out of options.

Regards, Dick Treen

[Tim Downie]

What happens when you remove the shower head?

If it's a venturi system that's worked in the past the only reason I can think of for cold water now going back up the hot supply is some sort of partial obstruction raising the resistance to flow after the venturi. (or a fault with the venturi itself).

Tim

[treenoakio]

[...]

No noticable change in flow rate or temp with the head and hose off.

The pipework and brass body of the unit have had a good flushing out recently, repeated several times.

(or a fault with the venturi itself).

I didn't want to replace the "Trevi Boost" cartridge unless I was forced to because of the cost, so I stood it in a caustic soda solution for 20 minutes, in the hope that the internals weren't made of aluminium. No sign of any damage as a result but not a lot of improvement in the performance either.

Regards, Dick Treen

[Tim Downie]

I know you said that the domestic hot water side of things wasn't touched but is there any chance that an air lock was introduced into the system somehow?

You say cold water is flowing back up the h ot supply. Does the pipe run cold all the way back to the HW tank or is it just a question of it running a foot or two back from the shower valve?

If there was an air lock and your hot supply runs up to the loft say and then down to the shower, it may be that the venturi isn't capable of producing enough suction to lift the water up to the loft.

Can you turn on *just* the hot water and get tank temperature HW (at low flow & pressure) from your shower?

I realise you've probably thought of all this but air locks can do funny things.

Tim

[treenoakio]

[...]

I think perhaps there was but not in this context. Since you mention it though, I still can't figure out why some pipework changes were made to the heating loop, so I'll ask here.

Originally, on the pipework to and from the DHW cylinder coil, the connection to the top port had a 22mm expansion pipe branch going up to vent in the tank area. The bottom connection port had a 15mm supply pipe branch from the header tank. For some reason the plumber found it necessary to cut and cap off the

15mm supply pipe a couple of feet above the lower cylinder coil port, then join the supply from the header tank into the 22mm expansion pipe a little higher up in the airing cupboard. All well and good not understanding the principle involved if things were ok but there seems to be a lot of air and gurgling in the loop now despite many bleedings.

Before the check valve went in, it was a couple of feet at a guess. Now that particular problem is sorted.

I don't think it's as complicated as that and the hot flow seems quite consistent.

I could when I had the unit stripped down and it was flowing ok. In it's fully functioning state the hot and cold turn on simultaneously.

Yes, hours of damp amusement and numerous opportunities to buy equipment that will probably never be used again. ;-)

Regards, Dick Treen

[Tim Downie]

That sounds small and will throttle HW output. It seems odd that your shower should have 22mm pipework when the cyclinder output is being strangled by such a relatively small input.

Now you've got me confused. The cold water feed shouldn't have anything to do with the coil which is for indirect heating of the cylinder contents and is fed from the CH boiler.

So there's no cold supply to the base of the tank??

Have a look at

and see if your tank connections correspond.

There really ought to be a 22mm cold feed to the base of the tank.

It sounds like you plumber has done something odd that is resulting in the shower sucking water from the cold feed rather than the HW tank. The gurgling noises would rather support this.

I think you need someone to cast an eye over your system (or post some photos of your tank connections and loft tank arrangements).

Tim

[Tim Downie]

Thinking about this on my dog walk I realised that in all liklihood, this is the CH system feed (from a small header tank in the loft), not the CW feed to the HW tank.

Does your new boiler have a pressure gauge and filling loop? If so, he's converted you to a sealed system and that would explain the capping off of the 15mm feed to te CH system.

Now that's still confusing me.

At the end of the day, you had a working shower before the plumber visited, now you don't. I don't think there's anything wrong with your shower valve and I think you need to get the plumber back to sort it out.

Tim

[treenoakio]

Thanks for the thought you've put in Tim. It was an an open vented system and remains so, though now it seems to either pull in air or make gas.

I got down on my knees and begged my wife to agree to me fitting the new boiler but she wasn't having any. Admittedly it would have taken me a lot longer than the "experts", during a particualrly cold spell. So, I minimised the job to just a new boiler and got a local firm to do it. The main man on the job seems to have had one of his hands removed by a mobile phone, poor bugger. And the electrician apparently shouldn't have been there at all because he was really management. I was alarmingly unimpressed with the quality of the job but I won't go into details. I promised my wife I'd keep my mouth shut and not criticize while the work was being done, or there would've been ructions.

I still can't work out why the expert joined the heating loop water supply and vent pipe instead of leaving them to enter the loop independently. I suppose I could restore the original setup and see if it improves the situation.

Regards, Dick Treen

[tim.downie]

I wouldn't. The original plumbers have a duty to get it right and if they've bodged it, you should give them an opportunity to put it right. I appreciate that you might not have much faith in them sorting it but I would tell them that you want the system checked

*before* you get another plumber in to mend it at their expense.

If they don't fix it after that you have a good case to get another plumber & charge the work to them (if their work is indeed faulty). You may need to go through the small claims court. If you start meddling yourself, you'll muddy the waters.

If you don't give them the opportunity you'll end up even more ot of pocket.

Any chance of some photos?

Tim

[treenoakio]

[...]

Thanks, point taken there.

I'm going to be away for 10 days but I'll put up a photo when I get back.

Regards, Dick Treen