Isolating valves

[Farmer Giles]

I'm no plumber, but I can manage relatively simple projects. With due regard to these limitations, I'm going to replace the shower in my son's property. It's a straightforward job, a 9.5kW electric shower over the bath - I've done a number before without problems. However, this time I've got a query that I hope the more knowledgable here will be able to help with. I want to fit a stop-tap/isolating valve before the shower so that in future it can be serviced/repaired without having to turn off the whole supply to the house. Because it is a 9.5kW one (yes, I'm going to replace the supply cable with

10mm one, etc), there is - or might be - an issue regarding water pressure. I understand that some stop-taps/isolating valves can restrict water flow fairly considerably, so - with that in mind - what would be the recommended way of dealing with this?

[Cicero]

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Just fit a 'full bore' isolating valve:

I would suggest the lever type if you've got space as the internal ball type can sometimes seize or leak.

Cic.

[Tobias]

Yes a ball valve of some sort would be a good choice. When open they are virtually "straight through" with no restrictions or deviations to reduce the flow/ pressure at the business end.

[cj]

[Farmer Giles]

Thanks to everyone for the help and advice.

I will fit one of the full-bore lever types from Screwfix (already ordered), and, yes, I will fit it under the bath as suggested.

[The Medway Handyman]

Gate valves are the spawn of satan.

[Farmer Giles]

I think you're right, they never seem to work well for me anyway. What do you think about the lever type?

[stephen.hull]

I've experienced very poor water pressure at the shower output end of a Triton Jade 8.5kw. Thinking it was the shower itself I replaced it (after a year) with a Triton Seville 9.5kw.

I previously had an isolating valve fitted and changed this to a lever type thinking the flow-rate would improve, sadly though it has made no difference, the problem I think is with the showers.

Our previous house (about eight years ago) and in the same area had a Triton shower fitted and this had a powerful head of water coming through.

The mains water pressure is fantastic but not at the shower end so I can only presume that the newer showers have some sort of built in restriction to save water as both the new showers are crap in comparison to the much older eight year old shower we used.

All three showers are fed directly from the mains.

Has anyone noticed this decline in water pressure on their shower?

Stephen.

[Andy Champ]

The shower heats the cold water as it arrives. The more kW, the more heat it can put in, so the more it can turn the flow up. At the moment the incoming water is pretty cold, so needs more heating - so it turns the flow rate down so you still get hot water.

Welcome to the world of instant heating.

Andy

[stephen.hull]

If I turn the shower to the coldest setting it has a satisfactory flow (albeit cold) until you start to turn up the hot water switch then it becomes dismal, I'll have to see if it improves during the summer when the heat setting will be set lower, giving more water output.

Cheers,

Stephen.

[Andrew Gabriel]

1990's house, there's one either side of the pump, so you can change it without draining down. Both gate valves have failed (started leaking) and had to be replaced, and of course you can't change those without draining down, so that was two extra draindowns. OTOH, the pump has never failed (yes, I know I shouldn't say things like that...)

There's another one on the tank outlet, which I wanted to turn off in order to remove a bath tap. Well, the gate valve shuts down to about 20% flow rate when fully closed...

I installed 6 of them as part of my central heating, so parts of the system can be isolated in the event of a leak and the rest carry on working. They were fine when I remembered to operate them once a year, but eventually that lapsed, and half of them are seized on (or at least, I'm not going to put enough force on them to free/break them without some very good reason). Two started leaking though the valve stem, but that was fixed by tightening down the nut. They're all 22mm.