Another Unvented HWS question

[Zippy483]

Hi Chaps

I have been lurking for a while and thinking of fitting an unvented cylinder, and have a few questions, which hopefully the Gnu's on here may be able to help we with so here goes.

1. Is an unvented cylinder a straight forward swap for my old vented, by this I mean once installed do i need to change any of the pipework that supplies taps showers etc for this system to deliver Hot water at a decent pressure. i.e do I have to upgrade from 15mm to 22mm say.

2. How much heavier is an unvented cylinder compared to a vented cylinder of similar volume?

3. Will my current boiler (in the general case) that supplies adequate hot water now be ok to use with an unvented system?

4. Assuming I decide to go ahead does any body know of a reputable firm of installers in the Rochdale/Manchester area, who will do a decent site survey and be able to recommend whether it is worth my while going ahead.


Many thanks

Zippy483

 

[Agile]

You need a MINIMUM of 22 li/min flow from the mains supply. Thats essential and any installer who does not check that is a cowboy!

You can keep the same distribution pipework but its better to change it to 15 mm, ideally radiating outwards from the output of the cylinder. Should be lagges too!

Weights about the same and boiler can do.

Tony

 

[GPlumb]

Why a minimum of 22l/m what happens under that?

 

[gas4you]

You will need that flow rate and ideally at least 3.5-4 Bar pressure, so there is enough flow and pressure to keep the balanced side of the hot and cold outlets balanced under most conditions.

 

[BigBurner]

Hi Chaps

I have been lurking for a while and thinking of fitting an unvented cylinder, and have a few questions, which hopefully the Gnu's on here may be able to help we with so here goes.

I advise against this. Get a vented zero-risk thermal store/heat bank.

Unvented cylinder blasts:

http://www.masterplumbers.com/plumbnews/2001/dec/avon.asp
http://seattlepi.nwsource.com/local/33094_boom28.shtml
http://www2.canada.com/edmonton/edm....html?id=02acabcc-e7c4-43e4-8fe0-5c298527e2d5

http://www.abc15.com/news/local/sto...orth-Phoenix-home/7p8jpeMzcU664FSrKb_osA.cspx

http://au.youtube.com/watch?v=pu3FwgIHsQA

http://au.youtube.com/watch?v=GF_Wrm-Ns0I

An exploding water heater ripped apart a north Phoenix home Thursday morning.

Video from Air15, near 40th Street and Thunderbird Road, showed a hole in the roof of the garage, a pile of rubble, and debris blown out into the neighborhood.

The water heater ended up on a sidewalk about two blocks away, across from a school.

Fire spokesman Victor Rangel said the temperature and pressure valve malfunctioned, sending the water heater skyrocketing.

Nearby residents were evacuated as a Southwest Gas crew and agents from Alcohol, Tobacco and Firearms investigated. Neighbors were allowed back into their homes after about two hours.

Many neighbors described the sound of a bomb, with windows shattering, walls shaking, and in one home pictures falling off walls.

A neighbor's wall was damaged by the explosion, which also broke windows in a house across the street.

One woman who lives two blocks away said the blast knocked all the pictures off her walls.

Click related link to right to see a water heater explosion.

Most of the damage occured to the house next door and directly across the street. However debris from the blast could be seen in yards and on roof tops.

According to Phoenix firefighters, the owner of the house was asleep when the blast ripped apart his garage about 5 a.m.

Red Cross relocated the homeowner.

No one was injured. [luckily]

Rangel said he's never seen this happen and he'd spoken to several plumbers who had heard of hot water heaters exploding, but had never seen it happen.

He said homeowners need to keep up with the maintenance of water heaters; sometimes the T and P valves become corroded or have been installed improperly.

Rangel suggests having the units checked by a professional, especially for people buying homes that have gone through foreclosure. A home bought after a foreclosure might not have gone through an inspection, especially in a short sale.

Water heater warnings and tips from the Phoenix Fire Department Most of the time, your water heater just sits where it’s been placed, quietly doing its job. But unlike your family pet, if it’s unhappy it’s not going to walk to the door and bark and scratch. It could just suddenly blow up like the one that exploded this morning near Thunderbird Road and 38th Street.

What? You didn’t know that your water heater could be so lethal? It can be if a tank has been improperly installed, if hazards have been allowed to develop over time, if it has been improperly vented, or if the pressure relief valve has been tampered with.

Here are some safety tips to use when operating your hot water heater:

TEMPERATURE/PRESSURE RELIEF VALVE (T&P)

This valve is designed to prevent a tank from exploding if temperature or pressure exceeds safe limits, by opening and venting. Unfortunately, residential valves are somewhat prone to failure. They should be checked once a year by pulling up on the handle. Water should flow freely out and stop when you let go of the handle. If it does nothing, runs or drips, then the valve should be replaced. Hooking up the drain line with a union or flex connector makes T&P replacement MUCH easier.
People don't like to test their T&Ps. But when water heaters explode, it's catastrophic. People are injured or die; buildings are severely damaged. Test your T&Ps!

Also, T&P drain lines should go down and out. Never up. If the valve opens, water will pool there and corrode it shut.
Finally, if water is running out of your T&P line, look for the cause. It might just be a bad T&P. But it could also signal high-pressure problems or a dangerously defective control. Don't ignore it!

 

[heatingman]

Could we have some UK based incidents relating to the failure of unvented cylinders please.
Please make it clear when posting the data that it is the failure of UK specification storage units with a seperate heat source.
Happy hunting.

 

[gas4you]

He can't.

He just wants everyone to fit unreliable rust buckets often known as thermal stores or heat banks

WARNING

If you want to take the advice of someone who is incompetent, unqualified and has never fitted a boiler, warm air unit, unvented cylinder or an accumulator in his life, then go ahead and listen to Big Burner.

All his information is obtained from brochures and the internet, which you can do equally as well yourself. In both mediums, manufacturers are always going to paint their products in a good light. Just search his previous, outrageous posts on here and then see for yourself. The only posters that appear to agree with him are those that are him using a different 'alias' and talking to himself.

He can never offer any qualified reason for his posts and always comes back with some pathetic off topic slur against anyone who exposes his true incompetence.

BB, you are still the laughing stock of this forum. RIP

 

[Agile]

Please be advised that Big Burner is NOT qualified to fit Unvented Cylinders or any Gas Appliances and he has never fitted any either !

Please take this into account if you read anything he says.

Tony

 

[kevindgas]

i've fitted many unvented cylinders, i have G3 qualification and to my knowledge there has not been a cylinder explode in Britain other than the one in the video used for training purposes which was in a FIELD and had been DELIBERATELY TAMPERED with
too fail would need A. conciderable pressure and B. complete failure of two pressure valves

 

[BigBurner]

Could we have some UK based incidents relating to the failure of unvented cylinders please.

So you want to see pictures of British bodies. How sad.

 

[DP]

It is common in the states for householder to go to their local Home Depot (B&Q equivalent). I am part a a discussion list which regularly highlights instances where the homeowner/ self fitter chooses to neglect good advise and proceeds to not install safety components. This list regularly speaks of homeowner who block PRV vents etc.

I am of the opinion that the picture in BB's post is one such incidence. Contrary to what he proclaims (UV cylinder need annual checks), heat stores also require annual checks like any other appliance.

Have been to properties where the cylinders he likes have caused damage due to ongoing leaks and corrosion.

This heatstore v unvented mudslinging is unhealthy. Why does BB not post facts based on proper findings instead of posting biased replies. I would prefer factual information based on proper investigative findings.

 

[kevindgas]

Could we have some UK based incidents relating to the failure of unvented cylinders please.

So you want to see pictures of British bodies. How sad.

NO WE ASKED FOR UK CYLINDER PICTURE - IS THAT PLAIN ENOUGH FOR YOU

 

[plumbnuts]

Agile
I'm confused about why you say that dh/cws should be run in 15mm on unvented systems. Please shed some light.
Steve

 

[DP]

Also, T&P drain lines should go down and out. Never up. If the valve opens, water will pool there and corrode it shut.

Only someone with no practical experience would write this.
Is it not a fact that a P&T run has a tundish fitted at the cylinder? Furthermore, only an idiot or someone not with G3 training would run such a discharge pipe contrary to what the regs specify

 

[BigBurner]

I am of the opinion that the picture in BB's post is one such incidence. Contrary to what he proclaims (UV cylinder need annual checks), heat stores also require annual checks like any other appliance.

I think you mean thermal store. No. DPS clearly state no annual service that as do Gledhill and others.

This heatstore v unvented mudslinging is unhealthy. Why does BB not post facts based on proper findings instead of posting biased replies. I would prefer factual information based on proper investigative findings.

A thermal store/heat bank is far superior to an unvented cylinder. They are not equiv, as a heat bank does CH and offers far, far more.

Anyone with an inkling of engineering education can assess the products.