NZ vented hwc



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wrote:

I couldn't get the link to work initially.
I can only assume that the pressure reducing valve is tuned to match the height of the vent pipe, such that when the system is hot the vent pipe is near enough full. The relief valve system seems to indicate this too.
On the basis that I live in a single storey house with poor HW pressure such a system is interesting, though I think I would retain the cold water tank for toilet flushing, etc.
Just how far away from regulations in this country is this ? <<<<<<<
The tank in loft system on page 2 has the OV going over the roof tiles. We do not have that any longer in the UK due to freezing. Maybe this is fine in the warm North Island of NZ.
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wrote:

I couldn't get the link to work initially.
I can only assume that the pressure reducing valve is tuned to match the height of the vent pipe, such that when the system is hot the vent pipe is near enough full. The relief valve system seems to indicate this too.
On the basis that I live in a single storey house with poor HW pressure such a system is interesting, though I think I would retain the cold water tank for toilet flushing, etc. ___________________
If you are retaining the tank then there is no point in using this system, which the prime aim is eliminating the loft tank in the vented version.
BTW, many people in the south of England when renovating, would go to France and pick up a load of building materials as it was cheaper. Many would unknowlingly fit in the French unvented cylinders, which pass a small amount of water into the drains because they had no pressure vessel - like a Megaflow when the air cushion dissolves, and the householder does nothing to reinstate the air cushion, which is quite common.
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wrote:

There is nothing wrong with the vented version as long as the OV is freeze proof.
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wrote:

It is open to the air, as the name OPEN VENT suggests.
It would have to be trace heated or completey within the insulated envelope of the building.
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wrote:

Ten out ten there. Very good.

Or up a disused chimney stack (inside the heat envelope) or us insulated pipework.
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wrote:

How would you get inside a disused chimney stack to make pipe joints, fix insulation and fix pipe supports?
Very few disused domestic chimney stacks go straight up, most step across with corbelling to connect to a chimney stack in the centre of the party or gable wall.
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wrote:

Run plastic pipe up and mabe secure at top. Cover with rigid foam insulation.
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wrote:

Have you ever heard of plastic pipe?
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wrote:

Yes, super stuff.
One thing you can't use it for though, is boiling water and steam. This is why the discharge pipes from boiler PRVs and unvented water heaters have to be metal. This application is an open vent pipe, for which you propose using plastic pipe in an inaccessible void.
Oh dear.
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wrote:

So that is why it is used on open vented system then. Wow!
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wrote:

It isn't; the open vent pipe is the discharge pipe for boiling water and steam in the event of the immersion heater thermostat failing in the 'ON' position.
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wrote:

It isn't; the open vent pipe is the discharge pipe for boiling water and steam in the event of the immersion heater thermostat failing in the 'ON' position. %%%%%%%%%%%%
Knob, it is open to atmosphere so "OPEN VENTED"
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Wrong. On unvented cylinders plastic HepVo traps can be used with a tundish and high temp plastic waste pipe used into the main waste stack.
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wrote:

Indeed; you've been Googling, well done you. For unvented water heaters it is some plastic made and marked as conforming to some obscure standard; I'd look it up if I were bothered. I've never seen it used. I doubt very much that it is flexible and could be dragged into an inaccessible chimney void as you suggested.
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wrote:

No knobhead!! Doing it"

Normal pushfit plastic waste pipe usually does it. mPVC
Normal polybuy' Hep2O is fine - the stuff that can be used on all vented hot and cold systems.
Please Google. You need it.
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It's a primitive unvented cylinder. What they are saying is that it can be vented if the OV pipe is high enough - all you do is set the pressure reducing valve to less than the head from the raised pipe.
In a flat I once owned, the tank on the roof gave me 1.5 bar. There was a 1" pipe from the roof tank to each flat. Most used this pipe to supply a break tank in each flat and having to use power shower pumps. I got myself a cylinder that took over 2 bar pressure. There was already two tees off the 1" drop pipe from the tank, in my flat. I took the bottom to the cold feed of the cylinder and the vent pipe to the top tee. Expansion would be back up the cold feed - it never got warm in the 1" drop pipe. I could not run a pipe up to the roof tank for the vent. I also put in a pressure relief valve set to 2 bar on the cylinder as a backup.
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wrote:

The presence of an open vent pipe would suggest to most people that it is not an unvented cylinder.
Ignore all other drivellings.
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wrote:

The presence of an open vent pipe would suggest to most people that it is not an unvented cylinder. <<<<<<
knobhead read what I wrote.
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wrote:

I did, Drivel.
You wrote...
It's a primitive UNVENTED cylinder........it can be vented if the OV pipe is high enough.
You're saying it is an unvented vented cylinder.
I'm saying you're the knobhead. Wibble.
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