Could anyone give me advise on the good and bad points of the Megaflow system and whether it is better than the conventional water tanks. Many thanks.
Jeeves
Jeeves
Megaflow water system
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Good points are, 25 year warrenty, no anodes to worry about, good solid construction.
Bad point- Having to regenerate air bubble periodically.
Altrenative is heat store. But this I would avoid as primary water quality can kill the cylinder.
Ensure the installation complies with building control i.e. plans are submitted to them. Installer needs to be qualified to install unvented.
Bad point- Having to regenerate air bubble periodically.
Altrenative is heat store. But this I would avoid as primary water quality can kill the cylinder.
Ensure the installation complies with building control i.e. plans are submitted to them. Installer needs to be qualified to install unvented.
W
Water Systems
jeevesy2000 said:
Thermal Stores/Heat Banks are far superior than unvented cylinders - and safer. Read below....
Advantages of Thermal Stores/Heat-Banks
- Instant high pressure hot water - When the store has reached temperature water is delivered instantly at the taps.
- High mains water pressures - At up to 10 bar, compared to 3.5 bar maximum with most unvented cylinders.
- Very high water flow-rate - The high-end heat-banks have a flow-rate up to 45 litres/min.
- Long efficient boiler burn - Eliminates boiler on-off cycling increasing efficiency and boiler longevity.
- Maintains optimum boiler temperature range – Using a blending valve the flow/return of the boiler can be kept to optimum maintaining greater efficiencies. The boiler operates at optimum performance.
- May combine the output of the stored water and the boiler - The boiler and energy in the store may be combined to increase output.
- Cylinder may be smaller for a similar performance - smaller cylinders than unvented cylinders.
- Cylinder at low pressure - Unlike an unvented cylinder vented stores do not store water at high pressures.
- Fast cylinder recovery rate - When the boiler is connected directly to the heat-bank, and not via an indirect coil, the recovery rate is rapid. Although in some cases a boiler may heat the heat-bank via an indirect coil, reducing the recovery rate.
- Legionella bacteria virtually eliminated - The Legionella bacteria cannot survive in the high temperature sealed conditions of a heat-bank.
- No scale build-up in heat-bank – Containing primary and not secondary fresh water, there is no scale build-up inside the heat-bank cylinder.
- Cold water storage eliminated - No need for cold water storage tanks.
- No BBA certification to fit – Unvented cylinders require an approved fitter to install. Thermal stores/heat banks require none and can be DIYed.
- Solar heating storage - Water heated via solar panels may be stored in the heat-bank via a solar coil.
- Easy maintenance - If an external plate heat exchanger requires cleaning or replacing it is a matter of draining down the heat-bank, or closing isolating vales, and unscrewing the plate heat-exchanger. In some rare instances plate heat-exchangers are fitted directly inside the heat-bank preventing on-site maintenance.
- Easy to improve hot water flowrates – By simply adding additional plate heat-exchangers in parallel, hot water flow rates may be improved. Retrofit additions are possible if extra bathrooms or showers are installed. This is impossible with unvented cylinders.
- Stored water vessel need not be cylindrical – As no internal coil is used for hot water heat transfer the stored water vessel may be any shape, as opposed to a thermal store which has to be cylindrical for maximum
efficiency. This has advantages where space is limited.
- No Annual Service Charge – Unvented cylinders require an annual service of between £60-£100. Thermal stores and Heat Banks are service free.
- Thermostatic Radiator Valves can be on all Rads - No wall thermostat required and TRV s on all rads when the CH circuit is take off the store cylinder and an auto modulating speed Grundfos Alpha pump used.
- Cheaper Smaller Boilers May Be Used – The large buffer of stored water means that a boiler sized for average use, not peak use, can be fitted.
- Larger Boilers may Be Used Without Fear of Boiler Cycling – A larger boiler can be used to reduce the cylinder size or give rapid heat recovery rates or both.
- Full Electric Backup of CH and DHW – An immersion Heater(s) can be fitted in the cylinder that will give CH and DHW backup very cheaply.
- Vented Thermal Stores/Heat Bank Eliminate Explosion risk – Unvented cylinders have an explosion risk. This is not a problem with vented thermal stores/heat banks.
http://www.waterheaterblast.com
- Pressurised Thermal Stores Don't Need Annual Service - No BBA unvented certification for fitting or annual service is required if a thermal store is pressurised and uses a plate heat exchanger.
Disadvantages of Thermal Stores Heat-Banks
- The store needs be near fully temperature to supply baths - Before any hot water is drawn off, the store must be up to temperature. Many later versions use a blending valve on the return to the boiler to ensure only up to temperature water is pumped into the store by the boiler. This prevents agitation of the stored water, and aiding heat stratification within the store giving useful water at the top of the store within a short time. The water is heated only in one pass through the boiler.
- Lower water temperatures with fast flow-rates - As with Combi boilers, fast flow-rates through the plate heat-exchanger results in lower water temperatures. This is not so pronounced with heat-banks as with internal coil thermal-stores. This also applies to combi's. With a heat bank, larger or extra plate heat exchangers can be fitted to increase flow rates. Sized up properly this is not an issue in operation.
- Needs more inhibitor - A minor added cost.
Advantages overwhelmingly to thermal stores/heat banks.
++++++++++++++++++++++++++++++++++++++
DP wrote:
Good points are, 25 year warrenty, no anodes to worry about, good solid construction.
Bad point- Having to regenerate air bubble periodically.
And an annual service charge by law. So, have it 25 years and that may be £2,500 at todays rates (more as inflation takes hold) just to have a cylinder of hot water in your house
Quote:
Altrenative is heat store. But this I would avoid as primary water quality can kill the cylinder.
Not so. Gledhill have a store that requires no inhibitor - the water only stays inside the store and goes nowhere else. Don't go on old wives tales.
__MOD 2
use the edit key ________________
Water Systems said:
No different from unvented then. Hot water is NOT available instantly at the taps, you have to flush the cold from the pipe first.
3.5 bar is adequate, and results in less wasted water. What are you going to do when you don't have 10 bar anyway? as most places don't.
Big deal
Store is maintained at a higher temperature so wasting fuel.
Shoved down the usual 22mm pipe, it will be a pointless increase.
Only if the temperature is higher. You are dealing with HEAT
You said earlier it was only 3.5 bar.
Please tell me where I can get some of these. I do not know the figures for people dying from legionaires' disease conracted from domestic water supplies.
Really? Depends on construction.
So why is this different from an unvented cylinder?
Do you mean thermal store?
But then unvented cylinders don't get annual services, and Thermal stores do require attention in my experience.
Building regs require a room stat.
Boiler costs vary little with size compared with the system cost.
Make your mind up.
As with unvented cylinders.
But with the 7 safety devices on an unvented cylinder the risk is negligible.
Yes they do, all pressurised systems are covered by BS7041.
Disadvantages of Thermal Stores Heat-Banks
- The store needs be near fully temperature to supply baths - Before any hot water is drawn off, the store must be up to temperature. Many later versions use a blending valve on the return to the boiler to ensure only up to temperature water is pumped into the store by the boiler. This prevents agitation of the stored water, and aiding heat stratification within the store giving useful water at the top of the store within a short time. The water is heated only in one pass through the boiler.
- Lower water temperatures with fast flow-rates - As with Combi boilers, fast flow-rates through the plate heat-exchanger results in lower water temperatures. This is not so pronounced with heat-banks as with internal coil thermal-stores. This also applies to combi's. With a heat bank, larger or extra plate heat exchangers can be fitted to increase flow rates. Sized up properly this is not an issue in operation.
- Needs more inhibitor - A minor added cost.
Advantages overwhelmingly to thermal stores/heat banks.
++++++++++++++++++++++++++++++++++++++
DP wrote:
Good points are, 25 year warrenty, no anodes to worry about, good solid construction.
Bad point- Having to regenerate air bubble periodically.
Please say what this "law" is.
You should take this advice. No doubt you will be trolling again.
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Hi Guys I have fitted dozens of thermal stores all replacements for failed units, I am also Unvented approved. If it was for myself, Unvented every time if you know anything about the hard water in lincolnshire you will know it eats thermal stores in months although that may not be the main problem, filthy heating circuits and undersized expansion I believe is the main culprit but hey everyone has an opinion cheers
W
Water Systems
ididdidi said:Hi Guys I have fitted dozens of thermal stores all replacements for failed units, I am also Unvented approved. If it was for myself, Unvented every time if you know anything about the hard water in lincolnshire you will know it eats thermal stores in months although that may not be the main problem, filthy heating circuits and undersized expansion I believe is the main culprit but hey everyone has an opinion cheers
It is clear you need to know more about Thermal Stores/Heat Banks. Heat banks use plate heat exchangers as opposed to immersed coils.
Plate heat exchangers resist scale build up as the stainless steel plates flex, although anti-scale precautions should be used in hard water areas as per any water system.
Undersized expansion in a vented heat bank/thermals store? Please? Read what I wrote. What you don’t understand come back to me.
My My you are the feisty one, as I said everyone has an opinion and mine is as valid as yours. Just going to have my dinner now will get back to this a bit later TTFN
W
Water Systems
ididdidi said:
I am not interested in opinions in any way whatsoever. I go by facts and intelligent analysis, not arm waving or what the fellas said down the caff.
The problem is that far too many people are out there knowing sweet FA, with little intelligence to analyse what is in front of them.
Water Systems said:
Like a group of people setting up a tank and launching it into space about what you would expect from the Yanks.
The film makers admit it was set-up WS, in this country it cannot and will not happen.
You haven't mentioned the High risk of scalding, a major worry at the HSE due to the high temperature, in fact the rules are changing to account for just that, ( read more expense )
Have you mentioned Gledhill sludge buckets yet, because I'm not going through your 1600 posts on the other channel again.
Why not just copy all your crap from screwfix and just paste it here, it would save a lot of time.
Why is it that so many of your posts start with "It is clear", when the only really clear thing is that you write nonsense and won't listen to anyone?Water Systems said:
And you repeatedly write "you need to know/listen/understand <bla bla bla>" to people who don't have the slightest interest in what you think they need.
Hm. Like that's going to happen.
W
Water Systems
oilman said:
What the hell is this one about!!! Mains water is instantly heated – it is not “stored”. If you want it instantly at the taps then you can a have secondary circulation pump.
This one is odd. The point is that you are not restricted using a PRV vale, that might fail. I have 3.5 bar mains and it’s not adequate for me.
- Very high water flow-rate - The high-end heat-banks have a flow-rate up to 45 litres/min.
Big deal
Try having two to three bathrooms at 20 litres/minute!!!! Where do they come from?
Wrong!!!! Store can be at 70 to 75C. With high cylinder insulation little energy is lost at all.
You can have 28mm pipe if it requires it. Boy are you dumb!!!
Wrong!!! Again. Boiler output is combined with energy in cylinder.
This one is thick. 3.5 bar is high pressure. Vented stores are at atmospheric which is zero pressure on the scale.
Oh the smart as doesn’t know something.
No thermal store or heat bank contains fresh water. Where do they come from???? Are you allowed in people’s houses.
It isn’t.
Heat bank. Heat banks have plates. Stores do not.
It is mandatory to have unvented cylinder serviced once a year. Ask your insurance company. Thermals stores don’t require an annual service at all.
Thicko, they don’t. They require a “control interlock”. No mention of a room stat at all thicko.
Read again. You are a thicko.
Read again. You are a thicko.
Thicko, unvented cylinders do not provide CH.
7? Three sequential. An explosion can still happen. Murphy’s Law says: If it can happen it will happen. Look at the link again.
No. A pressurised thermal store with an integral coil required an unvented ticket. One with a plate heat exchanger does not.
Look at this thread:
http://www.screwfix.com/talk/thread.jspa?threadID=40117&tstart=45 Best you stick to fitting toilets.
To others, sorry about the tone to this one. But this know-it-all needs it.
W
Water Systems
doitall said:
Will not happen!!! What a pillockl!!!!
The Titanic was not suposed to sink either.
The Shuttle was not supposed to expode either.
etc,
etc,
Boy!! Where do they come from? Bath?
W
Water Systems
Softus said:
Because it is clear.
*** cut babbling drivel ****
They let these into people's homes too.
On a previous topic, at 12:48 am on Friday July 7th:
And yet...Water Systems said:
Water Systems said:
Water Systems said:
Water Systems said:
Water Systems said:
Water Systems said:
Water Systems said:
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