Am thinking about replacing old combi with a conventional boiler. I already have a cold water header tank, and for space and location reasons am tempted to go for a high efficiency cylinder like an Albion CF45 or CF80. But surely they are not the *only* manufacturer of copper cylinders with high output / efficiency coils? I can find plenty of unvented stainless tanks claiming high efficiency, but don't want to go that route.
TIA
Yes there are many other manufacturers - but I went for an Albion Mainsflow, and am very happy with it.
It wasn't absolutely perfect, it arrived with one of the compression nuts missing, and that thread dinged. Fortunately in soft copper I was able to gently tap out the ding (which was less hassle than returning it).
Other than that, everything fitted together perfectly and has worked perfectly for the past year.
Came with an expansion vessel, pressure reducing valve & insertion temperature probe - all excellent quality parts.
an external 100kW heat exhcnager would give you high exchange rate
NT
Of course there is, it can transfer 100kW under specified conditions
Since the temp limits of unpressurised water are 0C and 100C, or in a practical domestic hot water sysetm much narrower, there's simply no way that _any_ heat exchanger can transfer 100kW under those conditions
NT
It sound to me like you are both off your trollies.
A car radiator on a powerful car is easily capable of dumping 100Kw of power. That's only about 240 bhp. Its neither a function of the temperature nor is it impossible.
Its a function of conductivity.
I think they usually mean 100kW transfer at typical input temps (say 5-10C mains water) and probably max possible boiler temp (say 80C). Of course, a modern condensing boiler would like to run rather cooler.
So if you assume the quoted delta-T is about 70C but if the boiler runs at
60C so dT=50C, scale the 100kW number back a bit (I assume 50/70*100 but I'll take corrections from people who know better).My PlateX is a nominal 100kW too - even if it shifts 50kW in practise that will be enough for a pretty decent HW flow.
Oh, what have I started?
But going back to the original thread, I don't want an external heat exchanger. I'm looking for a vented copper cylinder with a high output coil, and so far the only ones I have found are the Albion CF series.
FFs, answer the man's question.
He has probably topped himself by now.
Ring up the makers, they'll make you anything you want, for a price. Or use one of the standard dual coil jobs with the coils connected in series. IIRC Tribune do one that has a higher heat exchange area than a British Standard cylinder. The BS cylinder is much more efficient than the 'short-coil' horrors that were formerly sold. And they are more efficient, if used with a condensing boiler, due to the lower return temperature.
The copper coils required for the heat exchange area are expensive now hence the rise of the plate heat exchanger.
I once had a plate heat exchanger fail due to a blockage and enquired about a getting a tube-in-shell (copper coil) heat exchanger with the same duty. The manufacturers rang me back to say that, while they could make it, it would be 40 feet long and would probably affect the price of copper on the commodity markets. I got another plate heat exchanger.
Yes, Range Tribune that is, their Ultracal.
Why? If you have decent flow and pressure fit a high flowrate quality combi. Look at the Avantaplus 39C. You will not look back.
Quality, two bathroom combis are available. Cylinders? Madness, unless you have no option.
Not in my experience. A few years more and that is it.
Get a decent high flowrate combi and forget all this cylinder nonsense.
If you have a thing about cylinders and have their manual under your pillow then buy a small kW quality combi - 24kW or below if possible. The smaller kW models are cheaper. Buy a cheaper "direct" cylinder. Fit a Surrey valve on the draw-off tapping. Connect the DHW output to the Surrey Flange. Connect the cold inlet to the bottom of the cylinder. Fit a Wilo bronze pump to the cold inlet just before the combi. Fit a check valve just after the pump.
Set the DHW on the combi to maximum. The cylinder stat then starts the pump. The combi heats the cylinder directly via its plate heat exchanger - very quickly. It reheats the cylinder in a fraction of the time a coil would do it. It dumps 60C hot water at the top of the cylinder, pumping in 24kW. Useful hot water is available in a few minutes.
The cylinder can be downsized. The combi will supplement the cylinder and you will never run out of DHW.
When the cylinder is satisfied the bronze pump is off and the combi cuts out.
The NewTeam shower pump here is now 20 years old, and still going fine. (I hope I don't regret posting that...)
You are lucky. The bigger the family and more showers used the less they last.
The cylinder can be a cheaper, smaller, "direct" 80 to 100 litres model. No external mid-position valves and all that crap. Fit an Atmos Intergas combi and the DHW works even if the combi pump fails - there is no internal 3-way valve the combi is so simple.
If you do not want a combi,bi to heat the DHW (highly recommended) then buy an Avantaplus dual-temperature system boiler. Good and cheap. The stat and external 3-way "diverter" valve is wired into the boiler with the boiler automatically running up to max temp on DHW.
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