bathroom refit. what hot cylinder set up and what shower

[minmax89]

Hi all!

I'm about to do a bathroom re-fit in a bungalow.

The bathroom is at the far end of the house, next to the garage. It is a large en-suite to a guest room. I'll be replacing the bath with a shower and getting rid of the current electric shower and replace it with a Mira Vigour thermostatic power shower

Customer wants me to install a HW cylinder in the garage next to the bathroom. I'm going to fit a vented cylinder and so will need a CW tank. Looking into solutions, I remembered the combination cylinders that they use in apartments, etc. I thought this might be a great solution, time saved on installation etc. and would mount it as high as I could (to get the best head pressure) with still being able to service the ball cock, etc.

So I went to local plumbers merchants to look at them and the guy there's got me all confused about head pressure. He is basically saying to me that it doesn't matter how high i mount the combination tank as the HW cylinder is going up with it. The head pressure will be the same as the two tanks are joined together. He lost me there.😕

Can someone confirm, my head pressure is denoted by the distance between the base of the CW tank and the shower head right? or is it base of the CW tank to the pump - whether that be in the Mira Vigour pump on the shower wall or a seperate twin impeller pump at floor level feeding a thermostatic bar valve say?

To boil it down, do I do:

a) mount a direct cylinder at bathroom floor level, CW tank high above it.
b) fit a combination tank high as I can.

and the shower:

a)fit a Mira Vigour
b)seperate twin impeller pump with and thermo shower valve.


Few! Hope that makes sense.

Please go easy. I've been plumbing as part of my maintenance business for about 5 years so I know lots but there's more I don't know. And I'm all self taught.

Many thanks for your time and this site has been a god send for me.

Adam

 

[Irish]

The combination tank won't give you high pressure because the cwsc part is directly above the hot water cylinder part therefore not giving you any head on the cylinder, stick with a normal cylinder and cwsc high as poss or go unvented if you have your g3

 

[SimonG]

Electric shower or small unvented. Combination cylinder may struggle to keep up with a pump.

 

[Grandesporting]

Hi mate can you not talk the customer into an unvented cylinder?

 

[Grandesporting]

Unvented hwc??

 

[albatross]

A vented system in a bungalow will give a poor shower. You need an unvented cylinder, someone qualified to fit it. Also if it's attached to a gas or oil boiler it must be suitable for unvented. If not or you are on solid fuel a thermal store would do the job.

 

[stevetheplumber]

the guy in the merchents is wrong lifting the cylinder in relation to the shower will give more head but in a bungalow your never going to get it high enough to run a decent shower
the tank on a combination isnt big enough to pump

 

[Linkyplumb]

As above
You get 0.10bar of pressure for every meter upwards you go, so you would need to go up a lot more than a bungalow can offer.
Either unvented (if you have g3 cert), or 50 gallon cwsc and pump, with normal gravity cylinder.

 

[Ray Stafford]

Hi Adam.

There are two different issues here, and they need separating.

The Mira Vigour that you propose to fit is a (relatively low powered) pumped shower. The problem you will have if you fit that on a combination cylinder, is not related to pressure - the pump in the vigour will supply reasonable pressure (so long as there is enough flow to activate the flow switch).

Your problem will be the volume of water - the Vigour moves 14 litres a minute. This is significantly more than the ballvalve in the cold part of the combination cylinder can replace, so in a relatively short time, the pump in your vigour will be sucking air. This will not only deliver an unrewarding shower, it will also knacker your vigour.

(Incidentally, your merchant is talking nonsense - the pressure increases as the height of the cold water storage rises above the outlet - not above the hot water storage.)

You have a number of options.

1) Fit a conventional cylinder with an ordinary cold water storage tank. Get the latter as high as you can, but don't worry about the pressure, so long as you fit the vigour. You only need to get it high enough to make the flowswitch in the vigour kick the pump in. This advice does NOT apply if you choose to fit an un-pumped mixer. Concentrate on making sure it contains plenty of water - at least 40 galls, preferably more.

2) Fit an electric shower - flowrate at decent temperatures will be poor, particularly in the winter, and you may have work to get the cable in - depending on how far you are from the consumer unit.

3) Assuming that your cold main is giving plenty of flow and pressure, fit an unvented cylinder (for which you require a G3 ticket). If you go this route, forget the vigour, and fit an ordinary thermostatic mixer. The incoming main will take care of the pressure.

Which is best depends on your budget, the layout of the property, the performanve of the incoming main and how high your aspirations are.

Please don't attempt to take option 3 without getting the unvented G3 ticket - those appliances are really quite dangerous if fitted incorrectly.

 

[lame plumber]

that's all of us out of a job 🙂

 

[Best]

Adam, dont use your inexperience to alter your decision on what is best for the customer. By that I mean, it seems the customer wants a high pressure shower & with a stored hot water in the garage?
That would mean basically, if there is good pressure & flow on mains & no solid fuel boiler or Aga connected, then an unvented cylinder will be the simplest, best & likely by far the cheapest way to do this. Let a qualified plumber do the unvented if it is suitable.
Only other way is a 50 gallon or more tank in attic & copper cylinder somewhere in bungalow ( doesn't matter where except best it is not far from tank above & bathrooms ideally) plus a decent pump for shower(s) or individual all in one power shower unit.

 

[minmax89]

Brill. Thanks a million for all your replies.

To add I've done many jobs for this customer and he's very particular about certain things. He won't be persuaded to get another electric shower in and wants stored hot water that he can heat directly (immmersion) when he wants.
There is an existing HW cylinder and CW tank the other end of the property feeding main bathroom, kithen, etc., both a good distance away. This guest bathroom will be used intermittently so he wants to have a direct HW cylinder in the garage feeding this one bathroom. He will only switch on immersion when he has guests.

I ruled out the unvented option because
a) i know it needs a trained/certified pumber to fit - which I can get in but is gonna cost (parts & labour) considerably more than a vented system,
b)I'm not sure the pressure of the mains is too reliable (owners comments),
c)The higher installation cost isn't justified due to the amount of usage it will get during a year.

He doesn't want me to hook up to the existing HW Cylinder as he doesn't want to pull hot water that distance and this tank is adequate for his main bathroom but when adding the demand of the second bathroom, it's not.

The existing CW tank is on top of the flat roof of the bungalow. It currently supplies the main bathroom (with a Mira Vigour) and kitchen. it's as high as you could get one in this property. The one I propose to put in the garage would not be as high, obviously.
So, what about the option of this: new HW cylinder in the garage, fed by a new tap and feed to the existing CW storage tank at the other end of the property to feed a Mira Vigour in the bathroom/en-suite.

Any problems with the above idea?

 

[TBServices]

You'd almost certainly have to increase the size of that tank.

 

[TBServices]

You'd almost certainly have to increase the size of that tank.

Is the garage a flat roof or is there room in the roof space for a cistern?

 

[minmax89]

Is the garage a flat roof or is there room in the roof space for a cistern?

No, no roof space. whole thing is enormous flat roof

You'd almost certainly have to increase the size of that tank.

The existing CW tank you mean?

 

[TBServices]

The existing CW tank you mean?

Yes. And depending on the length of the run, upgrade to 28.

How much height do you have in the garage?

 

[minmax89]

Yes. And depending on the length of the run, upgrade to 28.

How much height do you have in the garage?

Same as bathroom ceiling, which is standard 8'.

 

[TBServices]

Build a platform for a tank, as high as possible and fit a shower pump.

If you can get enough head for flow through mixer, you can fit a ceiling switch to turn the pump on.

 

[Best]

I ruled out the unvented option because
a) i know it needs a trained/certified pumber to fit - which I can get in but is gonna cost (parts & labour) considerably more than a vented system,
b)I'm not sure the pressure of the mains is too reliable (owners comments),
c)The higher installation cost isn't justified due to the amount of usage it will get during a year.

Firstly, you need to get the pressure & flow tested before you rule out an unvented cylinder! If pressure is a steady 2bar or more & flow is about 20litre/min or more, then that would be fine.
Also, how can you say an unvented cylinder would be "considerably more than a vented system"?
A vented system in your case, needs a new cwt & a copper or stainless steel hot cylinder, plus all the pipework from one to another (considerable), also overflow pipe, heavy pipe insulation, valves & a place for the cwt.

Whereas an unvented unit comes complete with most gear & needs only a discharge pipe added & a motorised valve correctly wired. A cold tank with kit plus a copper cylinder alone will probably cost more than most of the complete unvented units!

 

[TBServices]

120l Unvented would certainly be cheaper than tank, cylinder and pump IMHO. Even if you spend £150 training and getting certified.