croydoncorgi said:
ACV CPSU thing is floor standing and weighs 174 Kg.
It is still a one box solution and contains a heat store.
I was aware of Heatweb products - and how much they cost.
I am not on about the costs. There are many makers of these products.
A heatstore such as the Gledhill Boilermate (ie. RELATIVELY low-cost) CANNOT connect efficiently to a condensing boiler, mostly because even with the contents stratified (not dependable in this respect) the Return temperature is still too high.
I don’t have that much experience with the BoilerMate so can’t comment on that model that much. I believe they have a model with a boiler take off coil and one which is heated directly. It was originally an internal coil model, but adapted to a plate heat exchanger. I don’t know which model you are on about. Any thermal store or quick recovery coil benefits from a TMV (UFH models) on the boiler flow and return. That maintains the top down heating and stratification. Next time you fit a BoilerMate, preferably heated directly by the boiler, not via a coil, fit a TMV on the boiler flow and return, near to the boiler, and it will be transformed in condensing operation.
The BoilerMate is an old model, that can’t be compared to the best available, although its efficiency can be improved if you know how.
Also, you're deliberately (?) conflating heatstores SEPARATE from boilers with condensing CPSUs - a different thing altogether.
A CPSU still contains a heat store. It is a thermal store with an integral boiler. The ACV was to show you that condensing can be maintained at all times which you said could not be at all.
I'd agree with you that IF you can afford one and IF you've got a site for it, the ACV thing IS efficient. So what?
You were maintaining that heat stores were not efficient using condensing boilers. Here is one that is, at
all times. Which counters what you believed.
It would take at least the machine's entire lifespan to recover the extra cost in saved energy!!
I assume you are guessing and have no figures to base this article of faith on. The ACV does about 3 bathrooms and cost about £2,300 the last time I looked. That is it. All you do is pipe it all up - saving on pipework too. Price up a separate large boiler and unvented cylinders(s) and see what it would cost with all the zone valves and the rest of the paraphernalia that makes the house look like a boiler room. Then the space the stuff takes up as well. The ACV will last a hell of a long time, it is very well made.
You can actually make your own highly efficient heat bank. Get a maker to make a stainless steel cylinder (can be copper, stainless coils take more mains pressure) with a small pancake coil at the bottom to pre-heat the cold mains water and lower the temp at the bottom of the cylinder, and tell them where to fit the tappings.
You can build your own very cheaply (parts are all stock standard and readily available) and make the internal spreaders too by drilling out the pipe stops on compression joints that screw on the tappings and inserting copper pipe with holes drilled in into the cylidner. Or you can use a cheap tall copper direct cylinder, tell them where you want the tappings, and use a couple of plate heat exchangers and the whole lot can work up to 10 bar mains pressure eliminating a PRV.
Understand how they work and how you can improve matters.
