You mean what YOU accept it to be. See my post explaining all the types of combi.
Loosing this one aren't you! As usual.
The word combi is short for "combination". All the heating and hot water are combined into one box. A one box solution. Now you know.
Unless you are a heating engineer, it is best leave it to the design engineers. You are neither.
Ah! he is learning. Yes they packackage the CH and DHW into one box.
No one said it was.
It is also what the industry accepts it to be - a boiler for producing instantaneous hot water and space heating as well.
You bang on about the apparent virtues of this versus storage systems enough.
On that basis, one could argue that CPSUs and other combined systems are combis.
The essence is still the same. In this case a relatively small 25kW boiler is augmented with a cylinder.
Neither are you. However I can spot spec. extrapolation when I see it, and this is being done here with respect to HW delivery. A lot is left unsaid. There's no clever engineering in it.
.andy
To email, substitute .nospam with .gl
Not true. The heat is being replaced in the cylinder by the boiler. The effectiveness of that will depend on the power level of the boiler and efficiency of the heat exchanger. Once the HW is used up, the temperature of the produced HW will fall or can be maintained at a higher temperature if the flow is reduced.
Well obviously. There's no difference between this and what I described above. If the flow rate is reduced, the temperature rise from cold mains can be maintained.
A much better solution is to have the cylinder adequately sized in the first place so that all the water likely to be required in the practical situation can be drawn at the higher flow rate and the condition of rate reduction does not arise.
Lovely. If you believe the brochures. There is a lot of missing information related to the performance and even Potterton engineers are not able to defy thermodynamics.
At 25kW heat input, the water is going to be being used in a decent shower faster than it is being produced.
.andy
To email, substitute .nospam with .gl
You could have one cheap 1/4 turn full bores valve. From combi's DHW draw-off insert a full bore valve. Fit a tee before and after the valve and have the electric heater between the tees. When the valve is open, most flow runs around the electric heater. When close all runs though the heater. Simple and effective.
This one is dumb! Read my explaination.
Gosh! he is learning.
The Alpha has an internal coil specifically designed to operate efficiently at the low flowrate stage. You willNEVER run out of hot water. The W-B HighFlow and Vokera using heat banks will not run out of hot water, but you have to manually reduce the tap to lower the flowrate. The CB50 does it automatically.
As stored water combi's have.
< snip drivel>
I believe in performance they deliver. You are the one quoting, and believing brochures, not me.
28kW on the Alpha, and delivering around 11 litres/min, which the whole of Europe, whoc have bought combi's of that flowrate by the millions, deem suitable for one shower.Now you know. Er, no. he doesn't. It will not sink in.
The whole thing can be avoided by having an adequately sized cylinder in the first place.
I pointed out the areas where the brochures conveniently avoid mentioning awkward data like the real flow rate for winter temperature mains water after the little cylinder empties..
Because that's what's available on the market. Twice that rate is needed for a worthwhile shower.
.andy
To email, substitute .nospam with .gl
Rubbish. A fast recovery cylinder will allow continuous 'hot' water - given that you refuse to define what you mean by hot, or the flow.
54kW or 22 litres/min? You must the size fo house to need so much.
But wouldn't the case stop the heat from the rads getting into the room efficiently?
In the winter, that is going to be a feeble 6.6L/min of water if you want it at the original 65 deg C...
(I do wish boiler manufactureres would use a more relistic temperature delta for their hot water output than 35 degrees)
You should know that IMM will adjust definitions so as to best suit the argument he is currently loosing... perhaps he should run for public office?
(Would fit right in with Mandelson, Byers, Darling, Jowell et al. Comparable level of competence as well).
Two showers? Shower and a bath? Decent flow rate on one shower?
11 lpm doesn't do it......andy
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< snip tripe>
What can be avoided? Auto 2 stage flowrates?
??? Do you mean we should all have large cylinders taking up needed space that also look like a school boiler house>
I said "I believe in the performance they deliver" and they deliver.
Nonsense!! High mad low flowrate combi's are on the market and now auto duel flowrates too. They have the choice and those with the low flowrates deem then more than suitable for showers.
You are prattling balls. Or are you a devil cult member wanting to rid the world of its natural, resources?
The man is telling you to size to suit.
Where do they come from? A shower is approx 43C.
Yes. It's a completely unneccessary compromise
No, because the space is not significant and it doesn't look like a school boiler house. You're suggesting putting a large box weighing over 130kg on the kitchen wall that even then doesn't do the job properly. Kitchen wall space in most homes is at far more premium than the airing cupboard.
I believe in a few things as well, but not generally not from glossy brochures.
???
What on earth are you talking about?
.andy
To email, substitute .nospam with .gl
Prattling balls as usual. One of these NEVER runs out of hot water.
In most smallish Britush homes it is.
It does.
Not large.
Weight doesn't matter as you don't lift it to have hot water.
It more than does the job and NEVER runs out of hot water.
So you say. It can go under the stairs, in the loft, etc.
Read back on the thread. You believe the Potterrton glossy on what is a combi rather than the Builing Research Establishment.
You are a waster.
I know you are. The rate reduces to low level, an issue which can be avoided.
Perhaps there should be land value tax on airing cupboards to deal with this.
We already covered that point and the limitations.
or even the airing cupboard....
I think that the boot is on the other foot.
I think that that is the pot calling the kettle black .andy
To email, substitute .nospam with .gl
Yes you are right, a 60kW combi would solve the problem and still within the capacity of the smallest domestic gas supply.
That may help. But as an airing cupboard is not land, it is difficult to tax it.
No limitations. It NEVER runs out of hot water.
No. as it take up needed space in there. Even if it was in the cupboard it would only be on a back wall taking little space compared to a large cylinder.
Yes, my foot.
You are mad
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