I've recently moved into a house which is around 3 to 4 years old and there
is a thermostatic shower fitted in the bathroom.
The only problem is that it isn't very hot - The dial goes from 0 to 9 and
it only has warmth to the output between 8 and 9, with 8 being mildly warm
and 9 being just warm enough to shower.
The water flow rate and heat from other taps is very good - The cold is very
fast and the hot has a slower flow rate (but not bad by any means) The hot
water is also nice and hot (too hot to wash with on it's own)
The hot water comes from a combi boiler which I assume is fed via the cold
mains pressure (i.e no tank)
Anyway, is this just an indication of the fact that the shower is knackered
and needs replacing? Or that the system is "inbalanced" in some way in that
the cold water which has a higher flow rate is just "overpowering" the hot
Basically my question is should I just get a new one fitted or are
thermostatic showers usually fitted with some means of adjusting the input
ratio of hot to water? The shower is made by Sirrus - Are they any good?
Any ideas (or suggestions as to an affordable make and decent quality
This may simply be that the boiler is not producing enough hot water,
or it could be the shower.
At this time of year, the mains cold water is quite cold - 8 degrees
is fairly typical.
It would be useful to know the make and model of the boiler.
You could usefully measure the flow rate and temperature from a hot
tap. Use a container of a known size - e.g. a 5 litre bucket and
time how long it takes to fill. THen you can work out the flow rate.
Now measure the flow rate of the shower.
To give you an idea, a shower needs to be at about 40 degrees so you
can work out how much cold is added to what the boiler is producing.
Obviously if the flow rate from the shower is greater than from your
hot tap it means that either a fair amount of cold is being mixed in
or that it is simply passing through the boiler more quickly when
feeding the shower, which also means that the water reachin the shower
will be cooler anyway.
This will give you an idea of whether the limiting factor is the
boiler or the shower.
I think it's worth doing this exercise before you rush off an buy a
new shower simply because it could easily be that the boiler is the
In terms of new showers, I would look at Mira, Aqualisa, Grohe,
One of my showers - Aqualisa with a standard valve, hose and standard
showerhead (not one of the large drench types or multiple heads
delivers around 20 litres per minute..
How would you suggest that a 9-11 lpm combi could deliver its needs
when the cold water temperature is 5 to 8 degrees, the shower
operating temperature is 40 and the boiler is specified to give a 35
degree temperature rise?
... or did you mean something akin to an electric shower..??
You add cold to take the flow up and 10 litres a minutes is a good
economical and environmentally friendly shower. I the USA local,utilities
went around to each home and fitted flow regulators free to each shower
giving a 8 litres/min shower. Few complained about performance. They saved
building another power station, with the power saved from wasting
unnecessarily heated water.
Checked by AVG anti-virus system (http://www.grisoft.com ).
Version: 6.0.558 / Virus Database: 350 - Release Date: 03/01/2004
Hang on a second. If the water going into the boiler is at 5 degrees
and it uplifts the temperature by 35 degrees, that takes it to 40
degrees by my addition. This is shower temperature. Where is the
scope for adding more cold?
10lpm is not much more than an electric shower and they are certainly
disappointing. It may be environmentally friendly, but it's not much
cop is it? If you are going to follow this line of reasoning then
you might as well advocate not showering at all - that's even more
environmentally friendly from one perspective but not that much from
To email, substitute .nospam with .gl
Big deal. I don't really care what they say. It depends on your
definition of adequate.
You might as well say that a milk float is adequate. It is if
you're delivering milk in the wee small hours and don't want to wake
people up and perhaps if you have a old one for taking stuff to the
tip, but apart from that, its uses are limited.
I've got a book entitled "101 uses for a Dead Cat". I'll add "shower
provision according to IMM" to it.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.