Poor pressure on a megaflo??
- Thread starter davecon1
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Hey Chris
He did mention that he was the only engineer that I would ever see regnerate the air gap that way. He didn't even try it the 'normal' way and instead hooked up the house to an outlet at the bottom of the megaflow, shut off the cold feed, opened the lower hot tap and then then siphon on the megaflo so the water would flow out downstairs! He then twisted the pressure release valve and lots of gurgling came afterwards.
It might have been unconvential but touch wood it seems to have down the trick!
He did mention that he was the only engineer that I would ever see regnerate the air gap that way. He didn't even try it the 'normal' way and instead hooked up the house to an outlet at the bottom of the megaflow, shut off the cold feed, opened the lower hot tap and then then siphon on the megaflo so the water would flow out downstairs! He then twisted the pressure release valve and lots of gurgling came afterwards.
It might have been unconvential but touch wood it seems to have down the trick!
Any reason why Megaflos shouldn't have an external expansion vessel fitted so that the internal air gap did not need to be maintained? Would an external expansion vessel instead of an internal air gap not increase the volume of hot water available?
Since the expansion vessel, like the air gap, acts as an small accumulator, it could be oversized (to the extent of the space available) to boost the short term flow rates where the cold supply was inadequate. Even a modest 24 litre expansion vessel might boost flows by a useful 6 litres/min for a couple of minutes, depending on static and dynamic pressures. For someone who likes short, sharp showers this might be entirely satisfactory.
Since the expansion vessel, like the air gap, acts as an small accumulator, it could be oversized (to the extent of the space available) to boost the short term flow rates where the cold supply was inadequate. Even a modest 24 litre expansion vessel might boost flows by a useful 6 litres/min for a couple of minutes, depending on static and dynamic pressures. For someone who likes short, sharp showers this might be entirely satisfactory.
No reason, it is done to save the periodic re-establishment of air gap thing, and provide more capacity as you say.
Volume of an air gap 50cm diameter 20 cm tall is 40 litres though, so that's the accumulator-like size if the dip tube is 20cm (is it ???). Whereas a vessel only used to accommodate expansion only needs to be about say 10% of the water volume. Water expands about 4% between 4° and 100° iirc.
Volume of an air gap 50cm diameter 20 cm tall is 40 litres though, so that's the accumulator-like size if the dip tube is 20cm (is it ???). Whereas a vessel only used to accommodate expansion only needs to be about say 10% of the water volume. Water expands about 4% between 4° and 100° iirc.
40 litres would be the volume of air at atmospheric pressure, whereas an expansion vessel will have a precharge air pressure, so its volume is not directly comparable. Wouldn't the 40 litres at 0 bar gauge pressure (atmospheric) become 20 litres at 1 bar?
There is no reason i can see why you couldn't fit an ext expansion vessel to a Megaflo, other than it might alter the approvals legal situation.
OSO cylinders come with a removeable dip tube so you can run them with an ext expansion vessel if you want, with an enlarged storage content. If you use the dip tube air gap the combi valve is set at 2.1 bar (because of the limited exp area), with an external exp vessel 3.5 bar at the combi valve can be specified.
You could add a small accumulator with the Megaflo, Chris. However, there are two potential problems. The first is that unless you fitted a flow restrictor, the small boost would be pushed out in seconds. Secondly, there are licensing conditions in place preventing Megaflo being enhanced by accumulator technology.
OSO cylinders come with a removeable dip tube so you can run them with an ext expansion vessel if you want, with an enlarged storage content. If you use the dip tube air gap the combi valve is set at 2.1 bar (because of the limited exp area), with an external exp vessel 3.5 bar at the combi valve can be specified.
You could add a small accumulator with the Megaflo, Chris. However, there are two potential problems. The first is that unless you fitted a flow restrictor, the small boost would be pushed out in seconds. Secondly, there are licensing conditions in place preventing Megaflo being enhanced by accumulator technology.
But if the accumulator was actually called an expansion vessel or a surge tank would it still be subject to those licencing conditions. And how can they be imposed on the end user (both in theory and in practice)? Might I be sued (and by whom) if I fitted an expansion vessel to a Megaflo?simond said:
Yes, I did go through that above. There's nothing to say that a vessel has to have any particular precharge. It can be zero if you want, then the air in it gets squashed just like the air gap in a megaflo.CH said:
Whom are you addressing? It depends what you mean by small and what you mean by seconds - the air gap in a Megaflo lasts quite a lot of seconds... it depends on the incoming supply and the outlet rate.SD said:
Heatrae Sadia will advise if asked about adding an external pressure vessel to a Megaflo. I can't remember the details of the size they suggest but obviously as it gets bigger and its pressure drops it does more accumulating.
Some years ago when I spoke to a GAH technical advisor about the Dualstream product, I was left feeling the guy was trying to sell a line without knowing what he was talking about - or having nothing to sell. Many unvented cylinders come with a pressure vessel , or without them but where they must be used. When does a pressure vessel become an accumulator?
What is their "accumulator technology" do? As far as I can see they don't even heat it.
If you're trying to boost volume you can of course put a pressure vessel on the inlet side of the multifunction valve, so it's isolated from the "unvented" system. A large water-hammer arrestor, perhaps. Does the patent seek to preclude that?
Some years ago when I spoke to a GAH technical advisor about the Dualstream product, I was left feeling the guy was trying to sell a line without knowing what he was talking about - or having nothing to sell. Many unvented cylinders come with a pressure vessel , or without them but where they must be used. When does a pressure vessel become an accumulator?
What is their "accumulator technology" do? As far as I can see they don't even heat it.
If you're trying to boost volume you can of course put a pressure vessel on the inlet side of the multifunction valve, so it's isolated from the "unvented" system. A large water-hammer arrestor, perhaps. Does the patent seek to preclude that?[/quote]
The accumulator has been patented in the UK by its inventor. Once granted a patent you have control over the exploitation of your intellectual property, providing the patent has been correctly worded.
The patent prevents unlicensed manufacturers from producing similar products. The licensing of the patent, in this case to GAH, usually involves the application and markets where the products can be sold.
Therefore whilst in principle, those aware of how the technology works can concoct their own hybrid solutions, any of these sold commercially and not approved by the patent holder or licensee will be on dodgy ground.
That's what a patent is for, of course. If you had designed something you would want to see it protected from unlicensed commercial exploitation.
For the record, over the last few years we have found GAH to be an excellent company with superb backup and technical knowledge. They support us (HWCH Ltd) all the way and are an example to many others in the heating industry.
Best regards
What is their "accumulator technology" do? As far as I can see they don't even heat it.
If you're trying to boost volume you can of course put a pressure vessel on the inlet side of the multifunction valve, so it's isolated from the "unvented" system. A large water-hammer arrestor, perhaps. Does the patent seek to preclude that?[/quote]
The accumulator has been patented in the UK by its inventor. Once granted a patent you have control over the exploitation of your intellectual property, providing the patent has been correctly worded.
The patent prevents unlicensed manufacturers from producing similar products. The licensing of the patent, in this case to GAH, usually involves the application and markets where the products can be sold.
Therefore whilst in principle, those aware of how the technology works can concoct their own hybrid solutions, any of these sold commercially and not approved by the patent holder or licensee will be on dodgy ground.
That's what a patent is for, of course. If you had designed something you would want to see it protected from unlicensed commercial exploitation.
For the record, over the last few years we have found GAH to be an excellent company with superb backup and technical knowledge. They support us (HWCH Ltd) all the way and are an example to many others in the heating industry.
Best regards
This is the accumulator marketed in this country by GAH as the Dualstream system, which I understand is manufactured by OSO. I can see that there are certain features (clench ring, diffuser?) that might make it different to similar products like expansion vessels and surge tanks, and I can understand that these unique features should be protected by a patent.
However I cannot understand how a patent can cover the use of any accumulator with any unvented cylinder, as claimed by GAH on their website. It all seems to hang on how you define an accumulator and how it is different to a surge tank, expansion vessel or indeed an air gap. All these function as accumulators whether one likes it or not. Below are examples of expansion vessels suitable for DHW, for comparison.
However I cannot understand how a patent can cover the use of any accumulator with any unvented cylinder, as claimed by GAH on their website. It all seems to hang on how you define an accumulator and how it is different to a surge tank, expansion vessel or indeed an air gap. All these function as accumulators whether one likes it or not. Below are examples of expansion vessels suitable for DHW, for comparison.
I do have to say that if an accumulator was fitted upstream of a Megaflow and before the pressure reducing valve then I would have thought that each installation would be stand alone and able to co-exist with each other.
Probably a reducing valve, non return valve and release valve would be required before the accumulator though.
So I for one would not be very bothered about fitting one!
Tony
Probably a reducing valve, non return valve and release valve would be required before the accumulator though.
So I for one would not be very bothered about fitting one!
Tony
What does that mean. Define "The accumulator" - the thing thay call an accumulator; any tank used for accumulating water - what??!!
That isn't what's claimed on the website - they say, paraphrasing, "when used in conjunction with a UV cylinder."
This discussion isn't going anywhere without the technical information!
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