On 29 Nov, 04:27, John Rumm wrote:
robgraham wrote:
I've been looking into using a venturi shower and was kindly sent a
large amount of data by Trevi. One thing that does puzzle me is that
their diagrams show the DHW head to be to the *bottom* of the cold
water tank and not the internal water level as I would expect.

Surely the head is the effective weight of the total cold water column
and therefore should be measured to the water level in the cold water
tank. I appreciate that most tanks aren't that deep to make a
significant difference but am I wrong or are they wrong ?

No you are right.

The only thing that possibly changes it is if the shower can draw water
faster than the tank can refill, then you may end up with the water
level at the bottom of the tank!

--
Cheers,

John.

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Interesting point, John, which I hadn't thought of. It would be in
the manufacturer's interest to make sure that the system has a bit of
buffer in the head and as you say the cold tank level could fall

So I'm right and the manufacturer is building in a margin - ie could
be said that both are right in their own way!!

Rob