ºOur customer has a large 3 storey Victorian detached property in Dulwich.
In common with many houses in this area, an old gravity fed hot and cold water system using loft tanks was employed.
Our customer wished to gradually update his house to new mains pressure fed bathrooms, using European high pressure taps, and wisely didn’t fancy the prospect of shower pumps.
He also wanted to make use of the loft space currently occupied by the large water tanks, and remove the old copper hot water storage cylinder on the 1st floor to make room for another shower.
Our brief was to design the plant to deliver his requirements, all within a cellar a little under 6 feet tall.
In the cellar we found a venerable Kidd Boiler, dating from 1990, so this was retained as it probably has a good few years of life left in it. Launched in 1982, it was an early condensing high efficiency design that remarkably few ‘heating engineers’ have heard of to this day, even though it was probably the first commercial British condensing boiler. Still made today, we still fit them!
Kidd Boiler Model 2 Gas (now available in white!)
I commonly hear ‘how reliable’ someone’s old Potterton has been………. if they had fitted a Kidd instead 20 years ago it would have been just as reliable but burnt just over half the fuel in the intervening 20 years. Notables including the Highgrove Estate and Peter Gabriel were savvy enough to understand the importance of not wasting fuel back then, but that’s another story….
We had to boost the water flow rate from the 20 litres a minute provided by Thames Water to in excess of 40 litres per minute. We did this with a stored water pressure vessel.
We then needed a hot water storage system that could fit below the low ceiling, but have a fast recovery time in the event of concerted use. We looked into a heatstore, but the costs of having a special unit fabricated to meet the space restrictions were very high. Also the Kidd Boiler does not modulate, so ideally we would need a heatstore with a 46Kw plate heat exchanger to enable the boiler to discharge its power in a long burn, rather than a protracted series of short cycles, which wastes energy needlessly.
We ended up specifying the ACV Smartline tank in tank ‘unvented’ cylinder instead. To those of you who think of a Megaflo when unvented cylinders are mentioned, this is a World apart.
ACV cylinder cutaway
The stainless steel water cylinder containing your hot water is suspended within another steel cylinder containing the boiler heated water. When the water is heated it is surrounded 360° by the boiler water, resulting in a very fast warm up time indeed.
So our Kidd Boiler can discharge it’s full output of 46Kw into the ACV cylinder, resulting in a quick heat recovery period.
The ACV cylinder has another trick; although it is an unvented cylinder, it is designed to store water at 80ºC, rather than the 60ºC usually used. The reason we normally store hot water at 60C is that at temperatures above this, limescale is precipitated from the water and deposits scale. The ACV inner cylinder is ribbed, and every water draw off causes a movement, this prevents scale from building up. The electrical immersion heater is fitted to the other jacket, so never scales up.
The result is that we can store more hot water energy in an ACV cylinder than an equivalent sized alternative, and most boilers will work more efficiently when driving them.
Water Boosting Vessel and ACV Smartline hot water unvented cylinder
The equipment was all mounted well below drainage level, so a Drainmaster high temperature compatible pumpset was fitted. The Kidd Boiler used to disharge its condense into a plastic 2 gallon drum (nobody manufactured condensate pumps in the 80s and 90s, so this was a common bodge), but now it can use the Drainmaster, along with a soon to be fitted sink, washing machine and of course the emergency discharge from the unvented system. The Drainmaster is a pump in a vented sump, and is hot water rated for these types of application.
The outside Kidd flue had been damaged by builders, so we commissioned a new hand welded item from Kidd Boilers (Mr Kidd, as usual, had the original installation drawings on file)
Finally, the latest Honeywell programmable room heating controller (CM927) was added to the installation to bring it up to date.
Honeywell Programmable room thermostst
We think the showers are now almost too painful to get under…….. but some of our customers like them like that!
