On 3 Sep 2005 04:39:53 -0700, wrote:


Image is delivering the flowrate to the body jet showers.

What flow rate? There was a recent thread here indicating that at
least 25-30lpm is needed for such a shower.

The Triton requires around 10 litres a minute minimum. The more the
better. I haven't seen any that state 30 yet.


If it's only 10lpm it's going to be pee-willy. Since Triton are an
electric shower manufacturer, I suppose that on that scale it would be
better than an electric shower. Just.


This is easily
achievable with a storage system.

With more expense and space taken up.

The expense is not significant, and the space issue isn't either
unless it's a one room flat or something.



The mid range Rinnai, at 54kW is using almost the entire throughput of
a standard domestic gas supply and still manages less than 20lpm, and
that is at a 33 degree rather than the standard 35 degree temperature
rise. Specifications on some models are for only a 25 degree rise.

It would take the 70kW one and a commercial gas supply to achieve the
flow rate needed for a proper body jet shower.

You exaggerate somewhat.

Not really. The figures are there to see.


?One outside model delivers 24 litres per
minute. The Triton Tower Shower takes a minimum of 8 litres per minute
at both the cold and hot inlets.

That's the *minimum*. 8lpm is nowhere near enough for a body jet
shower.

Rinnai's figures are for a 33 degree temperature rise. This means
that in the winter, with an incoming water temperature of 5-8 degrees,
the output temperature at the stated flow rate will only just about be
at shower temperature - there won't be any addition of cold water.

?The Rinnai can take up to 8 bar. The
Tower Showers will be at the maximum the mains can deliver up to 6 bar.
Tower showers are not thermostatic. This is where a Rinnai helps as it
accurately maintains the hot water temperature. The new 25mm plastic
main is delivering around 45 litres per minute at over 4 bar. The high
pressure is what people like in these showers.

Says who?

In any case this is irrelevant because the water heater can't heat the
water at that rate.

They have diverting
levers that switch from one set of jets to another keeping the flow
down.

Then it's not a full body jet shower but a compromise - just like an
electric shower. These should be able to deliver a good flow rate at
all jets simultaneously.


Fitting an unvented cylinder is way over the top in price and
consumes up lots of space and drops the pressure down to 3 bar or less.

It isn't over the top on price unless you are trying to cut corners
and costs. I thought you said that you were doing high quality
conversions.

If you have water stored at 60 degrees, you can mix it with cold and
achieve an excellent flow rate.



The same with a thermal store, except the thermal store operates on
higher DHW pressures. I doubt if the floor could take the weight of
such a large cylinder, and I am using the old airing cupboard for a
shower anyway.

If the floor won't support the weight of a cylinder, I would call in a
structural engineer before your luxury conversion collapses in a pile
around you.




The Rinnai will cope with two of them.


Two of what? Little pee-willy showers that are like electric ones
perhaps, but nothing much more.


I have checked it
all out, as you can see.

Mmmm.... I would suggest looking at the basic physics of all of
this rather than relying on the marketing blurb on manufacturer web
sites. That's where Drivel goes wrong.

The washing machine and dishwaters are cold
fill.

That's normal these days and even if they were hot fill, that is
almost irrelevant from the purpose of HW system planning


I "may" fit a combi, which are cheap enough, to do the
kitchen sink, utility room and downstairs toilet taps. Then there will
be no taps robbing pressure from the Rinnai when full on.

Huh....??? If you turn on the taps the pressure will drop.




Efficiency is quite poor. The 69kW input model has an output to
water of only 55.4kW - around 80%. This would not be allowed for a
normal boiler.

I queried this with Rinnai and they told me water heaters are exempt
from being condensing. The efficiency is about the same as boilers that
do not condense.

That's true and fairly pathetic. Even the Americans can produce a
condensing hot water heater that achieves a 95% efficiency.





A Rinnai is
not an over the bath Ascot.

In effect, that's exactly what it is, except mounted outside.

That is the best part of it.

As long as you don't mind an ugly white box on the wall. Do you
imagine that this would enhance saleability of a property, let alone
its appeal?




I
can't imagine why anybody would want a big white box on the outside of
their house. I would be surprised if their Japanese model is that
colour.

I have not looked at colours as I thought all were white.

In Japanese culture, white is the colour associated with death.



Look at their web site.

I have, and I am very underwhelmed.

A nice, neat, slim
white box on the rear wall.

I think it's plug ugly.

A white box is a white box.

Exactly.


--

..andy

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