Replacing Bath Shower mixer tap

[cemhlm]

In the next couple of weeks I will be replacing the existing Bath/Shwer Mixer Tap. Have spent a bit of time looking at the fitting of the existing mixer. A couple of questions I need answers to.

1. The existing connections show 22mm supply pipe to the hote water tap, but 15mm to the cold tap, is this normal?, I have looked at Screwfix item no, 13393 a Swirl Bath Mixer, it makes no comment on the connections.

2. The current connections are direct from the supply pipes to the tails of the hot and cold tap, I intend to change this connection to a flexible SS connection with a valve built in, using push fit, just a silly point, does the push fit end of the flexible pipe go direct onto the supply pipe and the washer screw end onto the tails.

Any advice much appreciated.

 

[TicklyT]

To save disappointment later, select brassware suitable for the water pressure you have available.

Gravity hot and cold supplies may have a pressure as low as 0.1 to 0.2 Bar.

Pressurised systems are usually much higher, say, between 1 and 5 Bar

Or you may even have a mains fed cold supply, and a gravity hot supply.

Gravity systems are usually piped in 3/4", 22mm or larger, where 1/2" or 15mm is often adequate for higher pressure systems.

Pushfit tap connectors can usually be fitted directly to taps, and the pushfit end fits directly onto a copper pipe of the correct size.

Older systems may have imperial pipe sizes which wom't match metric push-fit fittings.

IMO the bore of many flexible tails is too small to work adequately on a gravity system.

 

[cemhlm]

Thanks for info, the 22mm Hot supply is gravity fed, and the cold supply is 15mm direct from mains supply. the pressure from the hot gravity is pretty good, it comes out of the tap with a good head of steam, and from the cold an even greater rate of knots, fills the bath within 3-4 mins, unlike my son's bath fed from a combi boiler, you start filling on a Wednesday and then come back on Friday for a bath.

 

[TicklyT]

Don't confuse pressure with flow. Low pressure taps have large waterways to maximise the flow through them with the low water pressure available.

The pressure in a gravity system is controlled by the vertical distance from the tap to the cold storage cistern. The cistern would need to be about four stories above the bathroom to deliver 1 Bar of pressure (1 bar = about 10 Metres).

Mixer taps on mixed pressure systems are sometimes problematic concerning temperature regulation, and some can allow high pressure cold water to pass through the valve body, back-feeding into the hot system and causing the cold storage tank to overflow.

Many recommend installing a cold feed directly from the cold storage tank to the mixer to give matched water pressures and circumvent these problems.