Aagh!

Sorry James.
I clicked the wrong Edit button!

Read here

Yes, the knob has an adjustment for pressure...
... but it's also a filter (unless the installer removed the cartridge).

Posted by: @jamespa

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Regarding the w/machine its very odd that the hot water is high pressure but there isnt sufficient pressure to fill the machine. 

I suspect it's a "Cold Fill" only machine.

Posted by: @transparent

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Yes, the knob has an adjustment for pressure...
... but it's also a filter (unless the installer removed the cartridge).

I didnt realise that they also had a filter, but it makes sense.

Posted by: @transparent

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Posted by: @jamespa

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Regarding the w/machine its very odd that the hot water is high pressure but there isnt sufficient pressure to fill the machine. 

I suspect it's a "Cold Fill" only machine.

Me too, but either the cold fill is fed from the 'mains' (actually water from a well) or its fed from cold outlet of the inlet group to the DHW tank, which will be at the same pressure as the DHW.  The former must (presumably) be higher pressure than the latter and OP says he has problems with too much water pressure on the hot.  

@jamespa DHW - direct hot water? Large tank labelled Kodiak? Or should I be looking for another tank. Know most of old, rather agricultural, plumbing was removed and presumably replaced.

Posted by: @dwynwen

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@jamespa DHW - direct hot water? Large tank labelled Kodiak? Or should I be looking for another tank. 

Domestic hot water and yes its the large tank labelled Kodiak which, hopefully, is the only tank they fitted.

Posted by: @dwynwen

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@jamespa Know most of old, rather agricultural, plumbing was removed and presumably replaced.

Ah, that may account for increased pressure in the hot water.  This would be described as a 'upgrade'!

Transparent and I now agree what the grey valve/filter does so you can use either approach to reduce hot water flow (but I would just try the lever valve first - its the simplest by far!)

This graphic is mainly for @jamespa and I to chew over,
and particularly the pipe I've annotated in light purple.

The only question for @dwynwen is to clarify if the pipe labelled in light green is connected to anything.
We can't see that in the photos.

Note to James: I too have a well.

That means my house has several different pipes which carry cold water.

To ensure that cold water being fed to the showers and bath is at the same pressure as the hot supply,
I have one cold pipe-network which gets fed from the same pressure adjustment valve as feeds into the hot tank.

Is it possible that the installer has used the 'wrong' cold supply pipe in @dwynwen 's  house?

Is that why he's seeing pressure differential when there shouldn't be any?

Posted by: @transparent

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This graphic is mainly for @jamespa and I to chew over,
and particularly the pipe I've annotated in light purple.

The only question for @dwynwen is to clarify if the pipe labelled in light green is connected to anything.
We can't see that in the photos.

Possibly nowhere, just a diligent installer insulating a tail?  I think it might be intended for a direct-attach expansion vessel see here

Posted by: @transparent

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Is it possible that the installer has used the 'wrong' cold supply pipe in @dwynwen 's  house?

Is that why he's seeing pressure differential when there shouldn't be any?

I posted a reply to the question about the pipe. 

re your question above, where is @dwynwen seeing a pressure differential, Im confused (or forgetful).

There was an earlier post here where @dwynwen referred to high pressure in hot pipe and low pressure in the cold supply.

I have FOUR different cold supply systems in my house.

In my case I have the pipes colour-coded.

It's very easy to confuse them when installing stuff between several rooms.

@dwynwen just a reminder (as it was now a page of posts ago) to please post a picture of the handheld thermostat.

@jamespa Attached photos of green labelled pipe. Not as good as I hoped will send more if necessary.

Have turned pump on using thermostat. Very little noise in bedroom but distinct rumbling in kitchen below.

Thanks for all the help.

@jamespa Hand held thermostat: