U
undertrained
Might be, just might be, talking ballcocks.
Can a regular boiler work as a system boiler?
- Thread starter MM33
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Completely wrong B. You write so much stuff about which you know little. I was installing open vented stuff years ago and would not consider doing so now. The only time your comment could be valid is if considering a boiler replacement onto an old system, particularly if pipes are under solid floors.
But I have neither the time or interest in writing a detailed explanation. Your Googling skills should be able to educate you.
A leak is a leak. Sealing the system usually reveals one (but can occasionally cause one with dodgy existing pipework). With an f&e it just keeps topping up the system which is not good for water quality nor components.
The increased pressure in a sealed system, increases the likelihood of a leak and the amount of water which will be lost from a leak in the system.
I'm firmly on Bernard's side with this...
An open vented system is more complex to install, more expensive to install, but has several advantages over a sealed system.
1. Reduced chances of leakages and hence the system shutting down as a result of tiny amounts of water loss.
2. Generally DIY repairs are simpler, because more of the systems components are easier to access/not in the boiler.
3. Depending on the type of water use, an open vented system can be more economic in providing hot water, because the hot can come through to the tap quicker. Then too, both hot and cold taps can be run at the same time.
4. Often a larger gas supply pipe will be required when an opened vented is replaced with a combi.
My open vented system was installed in around 1984-ish and has had two replacement boilers. Each time the installer has wanted to convert my system to a sealed system. On one occasion a potential installer would not take on the job, because he only fitted combi boilers.
Open vented do have disadvantages..
1. They are much more expensive to install from scratch.
2. Need much more space.
3. A combi can be a cheaper source of hot water, when the owner's life is less predictable and HW use is unpredicatable.
In an earlier life, I was first responder to hundreds of commercial premises, which had heatings systems, ranging between house sized to large offices. The combi boilers gave far more issues than the open vented, the combi systems also took longer to fix and get back in service.
I'm firmly on Bernard's side with this...
An open vented system is more complex to install, more expensive to install, but has several advantages over a sealed system.
1. Reduced chances of leakages and hence the system shutting down as a result of tiny amounts of water loss.
2. Generally DIY repairs are simpler, because more of the systems components are easier to access/not in the boiler.
3. Depending on the type of water use, an open vented system can be more economic in providing hot water, because the hot can come through to the tap quicker. Then too, both hot and cold taps can be run at the same time.
4. Often a larger gas supply pipe will be required when an opened vented is replaced with a combi.
My open vented system was installed in around 1984-ish and has had two replacement boilers. Each time the installer has wanted to convert my system to a sealed system. On one occasion a potential installer would not take on the job, because he only fitted combi boilers.
Open vented do have disadvantages..
1. They are much more expensive to install from scratch.
2. Need much more space.
3. A combi can be a cheaper source of hot water, when the owner's life is less predictable and HW use is unpredicatable.
In an earlier life, I was first responder to hundreds of commercial premises, which had heatings systems, ranging between house sized to large offices. The combi boilers gave far more issues than the open vented, the combi systems also took longer to fix and get back in service.
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which happens very often.
Some leaks are little more than a weep.
Yes the F&E will replace the lost water in a vented system and that will add a bit more dissolved oxygen into the system. But then re-pressurising a sealed system does exactly the same addition of new water into the system. The F&E does this without the need for someone to operate the filling loop and the system keeps working. With a pressurised system the boiler may shut down due to low pressure and then be out of action until the system is re-pressurised by someone who knows how and is able to re-pressurise the system.
The other variable is the amount of "new" oxygen that comes into the system. How much oxygen is dissolved in mains water and how much oxygen remains disolved in water standing in a feed tank.
Not sure about that, there is the cost of pressure relief valves and filling loop valves etc etc
Installing a gravity drain pipe from the tundish under the pressure relief valve(s) can be difficulty.
Those costs are tiny, in relation to the costs of all the extra pipe work, tanks and cylinder of an open vented system.
Of the hundreds of combi systems I came across, I only remember one of them using a tundish. The tundish was located above the suspended ceiling in the managers office - why they had used a tundish wasn't obvious, because they could easily access an outside wall. On one occasion the tundish became blocked, overflowed and brought the ceiling down on the manager's desk. At which stage, I was called in to investigate.
There is no way anyone would be able to convince me to have my already installed open vented system, replaced with a sealed system and the extra space it takes up, is not an issue.
Somewhere along the way you have confused yourself over the difference between sealing up the CH circuit and converting to Unvented DHW. My post refers to the former.
But it doesn't change the bloody fact that the leak HAS to be found and remedied! Introducing new water into the system via either gravity open vent or filling loop, dissipates inhibitor and exposes sensitive components to corrosion and sacrificial deterioration!
A sealed heating circuit alerts the user to this defect more quickly than OV so that it can be dealt with. It is also the ideal solution to a system that is constantly drawing in air that f&e's regularly do through age, deterioration, poor design and more commonly... Modern equipment connected to the loop (UFH, designer rads, eco pumps, additional rads to name but a few).
I am not saying that rate of leakage can be ignored. No rate of leakage should be ignored.
But some leaks are slight weeps where water evaporates faster than it leaves the pipe. This causes little if any damage to the fabric of the building but it does cause a slow reduction in pressure until the boiler locks out on "low pressure". Not all home owners are capable of re-pressurising their system and thus need to get help to get their heating system working again. Could be a helpfull neighbour but could be expensive plumber callout fees,
In my case, I have solid ground floors throughout, no UFH and check the visible parts of my system regularly for leaks. Discoloured ceilings would identify any hidden leakages. I am not saying I have never had any leakage at all, but all of them were so tiny as to evaporate instantly and all at rad and pump unions, so easy to fix. None at all on pipes, rads or soldered joints, in the 35 years since it was installed.
I also spotted the heating header tank fill valve had seized shut last time I checked checked it 15 months ago prior to having a new boiler fitted, yet the tank was up to level, so I took the opportunity to replace the original galv steel tank with a plastic version and fit a new valve. Which confirms it doesn't have much water loss. I have a plastic hot water header tank in stock and ready to install to replace its galv tank eventually.
In my case I DIY installed heating and hot water into my Grade II thatched cottage, ( before anyone jumps up a GasSafe engineer installed the boiler ) in 2011. all vented and no problems. One "modernised" plumber ( not the boiler installer ) was very sceptical about vented systems but has now seen the advantages of open vented. He does a lot of work snagging "normal" systems into new builds.
Blue cylinder in the kitchen supplies hot water to kitchen, utility room and outside toilet ( used by florist who rents my outbuilding ), The valve actuator has been temporarily removed
Beige cylinder is in the bath room airing cupboard supplies low pressure hot water to basins and bath and via a second coil mains pressure hot water to the shower
A 12 volt operated valve actuator on the work bench
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