15mm or 22mm water feed

grumbler

Is it a new shower or a new one?  If the former, is it a power shower with a pump?

Anyway, I've never heard of a shower needing 22mm pipe for mains pressure water.

330d

It's a new thermostatic shower.

NSG666

330d said:

It's a new thermostatic shower.

What do the installation instructions say and will the shower be tapped off of the pipes feeding the bath? I fitted a Hansgrohe waterfall shower for a customer being fed from pipes in the loft and they said to run 22mm which would have been a pain to chop into the wall. I spoke with them and they said to run 22mm to the point the pipes went down the wall and run the last c. 1.2m in 15mm. Although the customer had a gravity fed system the shower was fed by a 3bar (similar to unvented cylinder) twin impellor pump capable of far greater flow rates than you will get from an unvented cylinder.

Do the cold feeds for the bathroom come from the pressure reducing valve of the unvented cylinder or are they being fed direct from the mains without passing through the pressure reducing valve? If the latter then just check this is ok in your shower instructions as they often recommend that they are fed at even pressures.

Another_Level

If the shower mixer/body jet valve has 22mm 3/4 inch inlet connections, Then fit the same pipe size to the mixer valve.
If its 15mm 1/2 inch inlet connections and the pipe runs to the showermixer/body jet valve are daisy chained plastic pipe, not knowing the other demmands&needs of the plumbing system. 22mm is favourite.

As its an unvented cylinder, using the balanced/pressure controlled port will offer balanced water pressure at the shower mixer/body jet valve.

Already mentioned the manufacturer's installation, will offer advice and cominisionning information.

Happy plumbing 

330d

So the instructions say the inlet is 1/2" so standard 15mm should be fine.

Little surprised because other similar showers that have the same head and jets have a 3/4" inlet. So strange why my shower only has a 1/2" inlet.

Is it worth fitting a 22mm pipe and a 1/2" reducer at the end?

Jeepers_Creepers

330d said:

So the instructions say the inlet is 1/2" so standard 15mm should be fine.

Little surprised because other similar showers that have the same head and jets have a 3/4" inlet. So strange why my shower only has a 1/2" inlet.

Is it worth fitting a 22mm pipe and a 1/2" reducer at the end?

No.

The reason your shower has 1/2" inlets is almost certainly because it's designed only for high pressure systems - ie combis and unvented tanks. It would trickle if fed from a tank in the loft. Pressure overcomes resistance.

You got a garden? You got a hose? How far does the water jet travel under mains pressure? How wet do you get if you stand in the way?

If that were my shower, I wouldn't replace any decent pipework already in position 'cos that would be a waste, but would reduce down to 15mm when running any additional pipework to the shower.

330d

Jeepers_Creepers said:

330d said:

So the instructions say the inlet is 1/2" so standard 15mm should be fine.

Little surprised because other similar showers that have the same head and jets have a 3/4" inlet. So strange why my shower only has a 1/2" inlet.

Is it worth fitting a 22mm pipe and a 1/2" reducer at the end?

No.

The reason your shower has 1/2" inlets is almost certainly because it's designed only for high pressure systems - ie combis and unvented tanks. It would trickle if fed from a tank in the loft. Pressure overcomes resistance.

You got a garden? You got a hose? How far does the water jet travel under mains pressure? How wet do you get if you stand in the way?

If that were my shower, I wouldn't replace any decent pipework already in position 'cos that would be a waste, but would reduce down to 15mm when running any additional pipework to the shower.

OK. 

So currently I am in the middle of a full house renovation. This included replacing the old regular boiler, cylinder and CWS in the loft with a system boiler and unvented system.

As the house is a building site, its not a lot of effort routing a 22mm pipe to the shower. So this is what i am trying to figure out, is it worth it? 

Jeepers_Creepers

330d said:

Jeepers_Creepers said:

330d said:

So the instructions say the inlet is 1/2" so standard 15mm should be fine.

Little surprised because other similar showers that have the same head and jets have a 3/4" inlet. So strange why my shower only has a 1/2" inlet.

Is it worth fitting a 22mm pipe and a 1/2" reducer at the end?

No.

The reason your shower has 1/2" inlets is almost certainly because it's designed only for high pressure systems - ie combis and unvented tanks. It would trickle if fed from a tank in the loft. Pressure overcomes resistance.

You got a garden? You got a hose? How far does the water jet travel under mains pressure? How wet do you get if you stand in the way?

If that were my shower, I wouldn't replace any decent pipework already in position 'cos that would be a waste, but would reduce down to 15mm when running any additional pipework to the shower.

OK. 

So currently I am in the middle of a full house renovation. This included replacing the old regular boiler, cylinder and CWS in the loft with a system boiler and unvented system.

As the house is a building site, its not a lot of effort routing a 22mm pipe to the shower. So this is what i am trying to figure out, is it worth it? 

Two Qs.
1) Are you using plastic or copper pipe?
2) What is your mains flow and pressure?

330d

Jeepers_Creepers said:

330d said:

Jeepers_Creepers said:

330d said:

So the instructions say the inlet is 1/2" so standard 15mm should be fine.

Little surprised because other similar showers that have the same head and jets have a 3/4" inlet. So strange why my shower only has a 1/2" inlet.

Is it worth fitting a 22mm pipe and a 1/2" reducer at the end?

No.

The reason your shower has 1/2" inlets is almost certainly because it's designed only for high pressure systems - ie combis and unvented tanks. It would trickle if fed from a tank in the loft. Pressure overcomes resistance.

You got a garden? You got a hose? How far does the water jet travel under mains pressure? How wet do you get if you stand in the way?

If that were my shower, I wouldn't replace any decent pipework already in position 'cos that would be a waste, but would reduce down to 15mm when running any additional pipework to the shower.

OK. 

So currently I am in the middle of a full house renovation. This included replacing the old regular boiler, cylinder and CWS in the loft with a system boiler and unvented system.

As the house is a building site, its not a lot of effort routing a 22mm pipe to the shower. So this is what i am trying to figure out, is it worth it? 

Two Qs.
1) Are you using plastic or copper pipe?
2) What is your mains flow and pressure?

1) House has a combination of plastic and copper. But the pipe going to the bath tub is 22mm copper. Current shower is 15mm plastic

2) Flow is 20l/min. Cant remember the pressure.

Another_Level

A standard shower mixer valve + a large deluge head on mains water hot & cold supply, works ok on 15mm.

4 Body jets on a 15mm supplies, will work ok.

Shower (deluge head) + 4 body jets running together may encounter water flow reduction, Pipe sizing and product selection is important.

Some say the setup will work, yes it will work (some water will flow) but maybe not as good as it should.
What does the installer recommend?  they have seen the particular layout and work out what is the best solution.

For the expense of getting 22mm balanced hot & cold supplies adjacent the mixer valve, its worth it.                                        
Plumbing 

Have fitted a few Crosswater 3/4 inch mixer/divertor valves