A shower dilemma...

[securespark]

If you just want to centralise the shower head, just buy a longer hose.

 

[CmdrBond]

How much pressure is required to not need a pump?

And how do you measure it?

I only ask because there are signs that there was previously some form of mixer shower feed from the hot water 22mm pipe and the mains cold water 15mm pipe.

My central heating is open vented, NOT combi.

 

[EFLImpudence]

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[flameport]

How much pressure is required to not need a pump?

There is no specific amount of pressure that is required, it depends on the shower valve fitted and what kind of shower you want. Some will work as low as 0.1 bar.
However if this bathroom is upstairs and the cold water storage is in the loft directly above, any non-pumped shower will be dismal at best.

I only ask because there are signs that there was previously some form of mixer shower feed from the hot water 22mm pipe and the mains cold water 15mm pipe.

That arrangement will not work - hot and cold must be at the same pressure, so hot from the cylinder and a separate cold from the cold water tank in the loft.

 

[CmdrBond]

If you just want to centralise the shower head, just buy a longer hose.

Not an option. Currently I have a deluge head with separate smaller spray. The current control unit is right where I need to put the shower head attachment. I could leave it where it was, but it will be a good 4 inches off centre of the new shower area, defeating the object of a wider shower area as I'll still be as close to one of the walls as I was before.

How much pressure is required to not need a pump?

There is no specific amount of pressure that is required, it depends on the shower valve fitted and what kind of shower you want. Some will work as low as 0.1 bar.
However if this bathroom is upstairs and the cold water storage is in the loft directly above, any non-pumped shower will be dismal at best.

I only ask because there are signs that there was previously some form of mixer shower feed from the hot water 22mm pipe and the mains cold water 15mm pipe.

That arrangement will not work - hot and cold must be at the same pressure, so hot from the cylinder and a separate cold from the cold water tank in the loft.

OK.

I need to crack on with the bathroom. It's looking like a power shower or pump and mixer is the way to go.

2 questions.

Can I use the existing (6mm²) wiring (changing the fuse at the consumer unit to 13A) to supply the built in pump of a power shower? If yes, is this notifiable or is it akin to replacing one electric shower with another?

How dismal is dismal for a non pumped mixer shower, compared to a 7.5kW or 8.5kW mains fed electric shower. It might be an option for me to plumb in a straight mixer as a temporary measure with a view to adding a pump at a later date.

With that last comment in place - how effective is Mira's "magniflo" that claims up to 3x more flow than a standard mixer?

Finally, for the pipe work, if fitting a mixer/power - plastic or copper?

 

[ban-all-sheds]

My colleague thinks this is OK to DIY, but I'm certain this requires part P (whereas simply replacing like for like does not).

Part P (in fact all of the Building Regulations) applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

 

[ban-all-sheds]

My central heating is open vented, NOT combi.

What is the capacity of your HW cylinder, how many people take showers over what period of time, and how long do they like to be in there?

 

[CmdrBond]

My central heating is open vented, NOT combi.

What is the capacity of your HW cylinder, how many people take showers over what period of time, and how long do they like to be in there?

Capacity - unknown. The cylinder is about 4 foot tall, I think.

I shower, the wife doesn't. It's only us. I take my time.

 

[Simon35]

My central heating is open vented, NOT combi.

What is the capacity of your HW cylinder, how many people take showers over what period of time, and how long do they like to be in there?

Capacity - unknown. The cylinder is about 4 foot tall, I think.

I shower, the wife doesn't. It's only us. I take my time.

When I fitted a shower pump and thermostatic mixer from my (at the time) vented system, there might have been a need to connect the hw pipe into the side of the cylinder rather than to the existing pipe out the top. Cant remember why, maybe pump cavitation. Anyway, it required hole sawing into the tank side and using an "Essex" connection, I didn't bother, didn't fancy the holesaw part, thought it might end in tears and no hot water. The pump was fine without.
The other problem was mesh filters in the shower valve getting blocked periodically with fine grit from what was an old set of tanks in the loft. The pump sucks water out of the cw tank along with any settled grit.
So make sure you either really clean the tanks, or fit new ones with good lids.
I've since had a combi fitted, which supplies masses of hot water at mains pressure and got rid of all those tanks and pumps.
Some food for thought for you.

 

[Lectrician]

When the pump pulls from the top outlet of the cylinder, there is a chance the pump will pull water quicker than it can be replenished, and suck air in from the vent pipe instead. This is why an Essex flange is recommended, so the pump is pulling from lower down. A Surrey flange can be used, which replaces the top cylinder connection, and has a long tube down into the tank, giving two outlets, one for the house, one for the shower. Reduced flow on both though.

 

[Simon35]

When the pump pulls from the top outlet of the cylinder, there is a chance the pump will pull water quicker than it can be replenished, and suck air in from the vent pipe instead. This is why an Essex flange is recommended, so the pump is pulling from lower down. A Surrey flange can be used, which replaces the top cylinder connection, and has a long tube down into the tank, giving two outlets, one for the house, one for the shower. Reduced flow on both though.

Cheers Lectrician....now I'm wondering why one's called a Surrey flange and one an Essex flange????

 

[ban-all-sheds]

One is much posher than the other.

 

[CmdrBond]

How much pressure is required to not need a pump?

There is no specific amount of pressure that is required, it depends on the shower valve fitted and what kind of shower you want. Some will work as low as 0.1 bar.
However if this bathroom is upstairs and the cold water storage is in the loft directly above, any non-pumped shower will be dismal at best.

I only ask because there are signs that there was previously some form of mixer shower feed from the hot water 22mm pipe and the mains cold water 15mm pipe.

That arrangement will not work - hot and cold must be at the same pressure, so hot from the cylinder and a separate cold from the cold water tank in the loft.

Actually - it just might - I have discovered Venturi Showers (Trevi Boost/Newstream Jetstream)

-----

Can anyone answer these questions?

2 questions.

Can I use the existing (6mm²) wiring (changing the fuse at the consumer unit to 13A) to supply the built in pump of a power shower? If yes, is this notifiable or is it akin to replacing one electric shower with another?

How dismal is dismal for a non pumped mixer shower, compared to a 7.5kW or 8.5kW mains fed electric shower. It might be an option for me to plumb in a straight mixer as a temporary measure with a view to adding a pump at a later date.

With that last comment in place - how effective is Mira's "magniflo" that claims up to 3x more flow than a standard mixer?

Finally, for the pipe work, if fitting a mixer/power - plastic or copper?

-----

My colleague thinks this is OK to DIY, but I'm certain this requires part P (whereas simply replacing like for like does not).

Part P (in fact all of the Building Regulations) applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

Thanks for the clarification - I was getting confused with what is regulated (practically everything) and what requires notification.

-----

My central heating is open vented, NOT combi.

What is the capacity of your HW cylinder, how many people take showers over what period of time, and how long do they like to be in there?

Capacity - unknown. The cylinder is about 4 foot tall, I think.

I shower, the wife doesn't. It's only us. I take my time.

Update, the cylinder is 117 litres.

-----

I've made a decision that I will not install a power shower.

I will install either a mixer (with or without pump, probably located in airing cupboard) OR a venturi shower.

Of the two options, the venturi seems to be the best due to time scale and access due to the whole house being upside down.

I'm just a little concerned with the venturi as to whether the existing plumbing is sufficient. There is thermostat on the HW cylinder already.

With that in mind, what is the best thing to do with the existing electrical cable. I am presuming that I should disconnect it from the isolator pull switch and rip it out of the wall. But what about the cable running to the Isolator. Should I just pull that into the loft and terminate it in a junction box, and pull the fuse from the CU?

Thank you for all your help.

 

[Simon35]

Best to disconnect from CU and from pull switch and mark each end. The other cable I would also disconnect from the pull switch and shower, mark each end and bury the shower end in the wall.

Then you can remove the pull switch and patch up etc.

 

[ban-all-sheds]

With that last comment in place - how effective is Mira's "magniflo" that claims up to 3x more flow than a standard mixer?

Sounds like a Q for the plumbing forum. Good luck

Finally, for the pipe work, if fitting a mixer/power - plastic or copper?

I would say copper. With soldered joints.

Some on the plumbing forum would agree. Others there would say that that view is archaic and blinkered and luddite and that there is nothing wrong with push-fit plastic. Often with the proviso "as long as properly installed", which is a great GOOJF card.