I will be installing a new shower shortly and was wondering if any of you had particular recommendations? Any pros and cons to look out for?
The water system provides hot and cold water at mains pressure (modulating combi). Static water pressure is OK (> 3bar), flow rate up to about 15l/min is available from the hot supply - although I would like to use less than that so as to have something left for the rest of the house.
The Mira 415 is the one to go for. Dedicated to mains pressure systems. It is not thermostatic and has an integral pressure balancing valve. The combi provides the constant temperature, so no need for a thermostat cartridge in the mixer. It works very well indeed. When you have equal flow and pressure on both hot and cold you don't need a thermostat (except where maybe children are about and they could play about). The 415 adjusts the hot and cold to equal pressure when any fluctuations. The reaction is far faster than a thermostat. The 415 is also simpler and if the thermostat cartridge goes it is usually over £100 to replace. Go for the Mira 415.
FUPOS !
Read my post. He doesn't need a thermostatic mixer with a modulating combi. He needs a pressure balanced mixer. I'm sure all this has gone right over your head. Read and learn.
I've been using a Hansgrohe Ecostat 2001 for about the last 6 weeks or so and it's excellent. I've also got a Hansgrohe thermostatic mixer/diverter on the bath which is great too.
I've tried turning on various taps (hot and/or cold) while the shower is running and the response is very good - unless you knew someone was going to turn the tap on I doubt you'd even notice really.
I suspect it depends on the exact details of the implementation, though.
Neil
What is FUPOS?
you seem to have accidentally snipped the interesting bit of my post - read it and learn
you are !
I would go for a good quality thermostatic valve like a Mira, Grohe or Aqualisa.
This will take out any temperature variations with different flows around the house due to taps being turned on.
You can easily control flow by virtue of using a smaller diameter hose or even restrictors if need be.
.andy
To email, substitute .nospam with .gl
You don't say........
Or use a pressure balancing valve or a dedicated combi/main pressure mixer, like the Mira 415.
Most quality mixers come with a flow restrictor between the hose and the mixer body. This is usually removable for full flow on lower pressure systems.
Hmm. We seem to be going down the want/need track again....
.andy
To email, substitute .nospam with .gl
There are better solutions than others. This is a better solution.
We have an Aqualisa "Aquavalve 609" thermostatic mixer in one bathroom and a Mira "New Excel" in the other. These are both run from a large (Eco Hometec) fully modulating condensing combi.
The Mira is FAR better than the Aqualisa at regulating the temperature when other taps or toilets start taking water. The Aqualisa typically runs very cool for up to I'd guess around 15-20 seconds, whereas the Mira almost instantly adjusts so you can hardly notice a temperature drop.
This may be due to something in the installation, but I'd be very surprised as the HW and CW supplies to both showers are taken separately from the boiler and CW feed down dedicated 22mm pipes that are not teed to anything else (as per earlier recommendations a while ago by "IMM" or the very similar "Adam" who mysteriously disappeared about the time that IMM appeared in this NG).
Regards, Simon.
You could try the Grohetherm 2000 or 3000, they are thermostatic and allow you to adjust the flow rate. there is a little button on the knob which stops at about 8 lpm, press it in and you can increase upto 18 lmp ( depending on your supply. Extremely well made and reliable.
Joe
The Excel has intregrated flow control. This reacts quite fast.
Why do you say the combi provides a constant temperature? Even modulating combis with a maximum water temp thermostats will vary temperature in inverse proportion to requested flow rate (the max temp rising up to the cap set by the stat at low flow rates)
So if you have the boiler stat set to limit at 60 degrees and draw off 8 l/min then the temp will be 60 deg. If the dishwasher then decides to take the total hot water flow rate to 15 l/min the temperature will have to fall. How does the pressure balance cope with that?
(I can see how it would work well on a unvented HW cylinder for example, because the HW flow rate would not affect the temperature of the water)
It has an output thermostat attached that modulates the burner to suit.
The temperature stability is not that precise though, but ballpark enough.
It will not fall. The burner modulates up to cope. Although some combi's are better than others in maintaining outlet temperature. Generally the more expensive the better the control.
If you are drawing 8 l/min and then taps are turned on to ramp up to 14 l/min, then the pressure in the hot line will drop. The balancing valve will drop the cold inlet to the mixer to the same as the hot, preventing excessive cold being drawn off through the mixer, keeping the temperature stable.
Yes, an unvented cylinder is better in this respect. But, some thermostatic blending valves will be mandatory on new installations. So, the speed of reaction of the blending valve may perform like a combi. When the blenders are mandatory, I would take the hot shower supply direct from cylinder before any blending valve. Although to conform to the future regs you have to install something like an Excel mixer with temperature limit setting.
We used an Aqualisa in exactly the same situation and it worked beautifully. Even when taps were turned on around the house and the flow reduced to not much more than a dribble at least the temperature remained constant.
Rgds
Andy R
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