I understood that a domestic gas supply will deliver 62kW. It doesn't leave much, does it......
I am sure that you would find a way if you could.
It drops to 11lpm. That's a BIG limitation.
The space would be the same as a cylinder and equivalent boiler unless you have a way to compress water. If you have, I would patent it quickly.
.andy
To email, substitute .nospam with .gl
If they can make the claim that such a unit provides 'continuous' HW then that term could (equally misleadingly) be applied to any modern conventional heating system with stored HW.
The limiting factor is likely to be the heat transfer rate between the primary and the stored HW.
The key question (after dismissing the disingenuous claims) is whether a) There is enough energy stored and added during the time of the largest demand. (probably one large hot bath full). b) That system is cabable of regenerating within a short enough time that a series of largish demands can be met.
The only advantages I can see for a one box approach (other than saving installer labour) are
a) The system might be able to sense that a demand is occuring and respond more promptly than a conventional system. A typical conventional system clocks the fact that a bath has been runn in a few minutes, so the extra is not that great.
b) The store can be run hotter than would be prudent in a conventional system. Again the difference beween storing at 80C v.60C is only percentages rather than a factor. Also there are draw backs with a hotter store. 1) The heat losses from the store must be higher and there may well be _less_ room for insulation. 2) The HW output must be blended to prevent a low flow rate demand producing hazardously hot water.
A very pertinent factor will be the maintenance costs viz all the parts of a "box" will be sourced via the manufacturer at a premium. Seperate boiler and cylinder with controls will be available from "any good store" at competitive prices
Still within.
No., just tax land.
It is not. You ALWAYS have hot water. The 1st stage give v good flowrates.
No it would not be. A cylinder takes up lots of space.
You are having a laugh of course. Only TWO advantages. Look harder please.
Hardly a good design to sail it so close to the wind. Not the design approach of a professional engineer.
On that we'll have to agree to differ.
For a while.
That would be because.... hmmm..... let me see..... ah yes, the stored water volume is smaller.
Groan.....
.andy
To email, substitute .nospam with .gl
Still within. A domestic meter can take 100% overload. The occasional blip over is no problem. Didn't know that did you.
No. Me thinking you haven't a clue.
Enough for normal domestic use and then no water run out at all. Brilliant eh!
Very clever!! 10/10. Another point is that the box is desighned to save space too. So overall only 5/10.
Some do that as well.
It is not a pertinent factor. Boilers don't brake down every month.
Obviously system components are designed with a margin. It remains bad practice to use them close to and certainly beyond their specification.
For those with low expectations perhaps/
So it's a T.A.R.D.I.S as well is it?
.andy
To email, substitute .nospam with .gl
A U6 212 cu/ft per/hr meter could handle 350 cu/foot no problem at all, and were installed to do so, despite having 212 on the front. The limiting factor was the supply pipe, which being 1" should deliver 350 no problem anyhow.
I can't comment on your devil doomsday wishes.
Sort of.
Could you produce a letter from Transco approving this as a working specification?
????
Ahh.. I thought so...
.andy
To email, substitute .nospam with .gl
Simple maths...
You start off with the stored water in the "system in a box" boiler at
65 deg and ample flow rate. As it runs out you revert to instant water heating. That can sustain the temperature at the above mentioned 6.6 lpm, or if you accept a fall in temp you can have the 11 lpm flowrate. Either will result in a significant drop in flow rate at the tap (i.e. well under half of what you started out with). If you have a non thermostatic shower you are likely to get you gonads frozen off.
The boiler reheats the cylinder as hot water is being drawn-off.
I see no maths only figures plucked from the air.
No. You have to take a professionals word for it.
The penny may be droppping.
That is generally your modus operandi, yes....
.andy
To email, substitute .nospam with .gl
That fills me with confidence.......
.andy
To email, substitute .nospam with .gl
So is capable of sustaining the same flow/temperature at all times? Care to state what this sustainable flow is and at what temperature?
Well, let's see some accurate ones. If you can.
Not that it is going to make much difference.... the boiler does not have the power required to sustain the supply rate in real time that would alow it to match the performance of delivery from its inbuilt storage tank. If it could, there would be no need for the storage tank would there?
Sorry, thought it was self evident - here we go with sub titles for the hard of thinking:
28kW Boiler - lets assume that is the power that is going to actually heat the water, and there are no other efficency losses to take into account.That is 28,000J / Sec, but we are interested in flow rate / min hence
28,000 x 60 = 1,680,000 J of energy available per min.Water takes 4200J of energy to raise its temperature by 1 degree C. We are interested in a 60 degree rise (65 final temperature less the assumed 5 degrees ground water temperature during winter). Hence the energy required is:
4200 x 60 = 252,000 J/kgSo the total number of kilograms of water than can be raised to the desired temperature is:
1680000 / 252000 = 6.67 kgWith 1 kg being equivilent to 1L (near enough) that gives you the 6.67 lpm
As for figures plucked from the air (your speciality I believe) the 28kW you supplied, the 4200J/kg/C is the specific heat capacity of water - go look it up if you want verification, the 5 degree ground water temperature in winter, is an arbitary figure that should be fairly representertive for most of the country. Oh and the sixty seconds in a minute figure I did just pluck from my memory...
I have had this sort of 'argument' with an engineer friend over steel beam sizing. My approach is that I like to have something in hand, notwithstanding the fact that a steel beam that can, by the codes, hold up 10 tonnes won't actually start failing until you apply a load of
15-20 tonnes, so I wouldn't use that section for a load of 9.9 tonnes. My friend's view is that this is precisely the section you should be using (unless you have some reason to expect that loads may increase in the future) as it is adequate and anything larger is needless expense: "an engineer is someone who can do for $1 what anyone else can do for $2" (anon).You're not unhappy about taking 13A out of a 13A socket are you? I can see no problem with taking 60kW out of a 62kW rated supply since (i) unless there is a major appliance malfunction there is no risk of this being exceeded and (ii) nothing very dreadful will happen if the pressure drops slightly - it's not like the gas main will glow red hot when you try and pull too much gas through it. Having said this I would think it unwise not to allow for the future installation of a gas cooker (if not already present) when determining the supply capacity
That is an improvement.
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