NZ vented hwc

[grimly4]

I didn't know of the existence of this system - a hwc fed from a pressure regulator and an open vent pipe. So simple, so cheap and no loft tank.

[Roger Mills]

I can't see how that works. Where does the expansion go - it can't go back into the mains?!

[Onetap]

It could go up the mains if there wasn't anything that acted like a NRV, but it probably just spills out of the OV pipe. The expansion vessel on unvented water heaters of >50 litres is a requirement of the UK Water Regulations, most other countries permit the expanding water to open the pressure relief valve and run to drain. The systems operate reliably like that. Spillage from the OV is probably allowed. There's nothing shown in the NZ systems that isn't available n the Uk, it isn't used because of the UK regulations. The UK spec equipment has better standard of controls, IMHO.

[robgraham]

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 ?

Rob

[Doctor Drivel]

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.

[Onetap]

The presence of an open vent pipe would suggest to most people that it is not an unvented cylinder.

Ignore all other drivellings.

[Doctor Drivel]

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 ?

[Doctor Drivel]

The presence of an open vent pipe would suggest to most people that it is not an unvented cylinder.

[Doctor Drivel]

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 ?

[Onetap]

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 k*****ad. Wibble.

[robgraham]

With the danger of this becoming a string of abusive posts, your comment, Onetap, is pedantic and nit-picking on words.

Rob

[news11paul]

FWIW, where I lived in NZ, the hot water cylinder was in the basement and the overflow pipe stuck out of the roof by a metre or so. If I was to test my failing memory, I'd guess there could have easily been 4-5m of pipe straight up.

#Paul

[Onetap]

You're entitled to your opinion, as I am to mine. My opinion is that Drivel is an idiot and that his usual self- indulgent crayoning over this thread is intended solely to give the impression that he has some expertise in the area.

It might help if you read the first couple of posts and then see which of the replies have given information as to why this system is permissible in NZ, but not in the UK. One of the posters has the G3 unvented ticket and might know a little about unvented water heaters; can you guess which one?

Are you a Drivel sock puppet?

An primitive unvented vented water heater with an open vent? Really? What did that statement tell you.

It won't turn into a string of abusive posts, I usually manage to ignore Drivel's inanities. I shall endeavour to apply the same restraint to your posts.

[Doctor Drivel]

You could probably make it legal in the UK; I think the Water Regulation requirements to prevent back-siphonage would be an obstacle. I doubt that the external OV would be allowed, you'd probably be required to have an internal tundish to indicate a malfunction of the reducing valve, again as with unvented.

I really don't see the point though. You have many of the complications of an unvented system in the water inlet group (Pressure reducing valve, non return valve), but not the benefit of higher- pressure hot water.

[Doctor Drivel]

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.

[Onetap]

Until the external open vent freezes, when it becomes unvented, although without the pressure relief valve and the T&P relief valve you'd find on a BBA-certified unvented water heater.

[Onetap]

[Mike Barnes]

Doctor Drivel :

[Doctor Drivel]

Until the external open vent freezes, when it becomes unvented, although without the pressure relief valve and the T&P relief valve you'd find on a BBA-certified unvented water heater.

[Doctor Drivel]

It would be nice if people didn't use google groups as this omits the ">"