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OSO Hotwater Super-S Series Cylinder

 OSO Hotwater
OSO Hotwater UK claim that lots of innovation has gone into their new 'Super S' unvented cylinder, so we thought we'd have a go at installing one.
Adjusting feet (click for more)
The floor may be level but just in case it isn't you might as well wind the feet out so they are at least level with the base. That way you can get at them to give them a little turn. I have a slight reservation about 18mm chipboard floors with this point load from the feet and would probably put down a piece of plywood. You will also notice that there are two channels for taking cables through from the cylinder stats, one for the immersion and the other for the zone valve.
Template (click for more)
The cylinder comes with a template, so you can accurately carcass out the pipe-work and leave it ready to connect.
 Piping up (click for more)
This is all familiar stuff if you are fitting boilers but for a cylinder it is previously unheard of to run the pipes up in this way. Brilliant! Why didn't anybody ever think of it before?
The floor may be level but just in case it isn't you might as well wind the feet out so they're at least level with the base. The cylinder comes with a template, so you can accurately carcass out the pipe-work and leave it ready to connect. This is all familiar stuff if you're fitting boilers but for a cylinder it's unheard of to run pipes up in this way.
Measuring the pipes (click for more)
Measuring the pipes to fit from the upstands to the compression elbows (supplied) couldn't be easier, and joy of joy they all line up with no awkward crossovers.
 Tighten (click for more)
I made a mistake putting that zone valve on top but I wanted it to be accessible because a cupboard is being built against the right hand side. What I hadn't figured on was that it sticks above the pipe cover but I was able to lay it on its side and it just fitted neatly between the pipes. My only concern is that it will get hot under that insulated cover so I might move it to behind and use push fits for easy removal.
 Milwaukee drill (click for more)
You don't need to see a Flamco bracket being fixed except that it is being fixed by this lovely little Milwaukee 12 volt Li-Ion impact driver which makes easy work for those coach screws. Coach screws? Overkill but Flamco put the same bracket on all their expansion vessels and some are a lot bigger.
Measuring the pipes to fit from the upstands to the compression elbows (supplied) couldn't be easier. I made a mistake putting that zone valve on top but I wanted it to be accessible because a cupboard is being built against the right hand side. You don't need to see a Flamco bracket being fixed except that it is being fixed by this lovely little Milwaukee 12 volt Li-Ion impact driver which makes easy work for those coach screws.
Expansion (click for more)
The expansion vessel has a flexible hose which makes it very easy. You can use this connection for a secondary return and tee the flexible hose in on a compression fitting. Also the pressure relief valve and temperature/pressure relief are both teed together by a stainless steel flexi which connects to the tundish. The pressure reducing valve and check valve are factory fitted so you can't get that wrong.
 Pipe bending (click for more)
It looks as if I am putting loads of effort into bending this 15mm copper but I am looking at the 90 degree mark on these Hilmor benders. A great idea but it isn't quite at 90 degrees.
 Levelling (click for more)
It is easy enough to adjust the feet at this stage but don’t try it when it is full of water.
The expansion vessel has a flexible hose which makes it very easy. You can use this connection for a secondary return and tee the flexible hose in on a compression fitting. It looks as if I'm putting loads of effort into bending this 15mm copper but I am looking at the 90 degree mark on these Hilmor benders. It's easy enough to adjust the feet at this stage but don't try it when it is full of water.
The electrical connections for the zone valve are clearly marked and if you can place it down at the bottom of the primary flow you can run the cable straight through that channel with no junction box. Next time I will do that. Also notice that the drain off cock is at the front where you need it to be. How many times do you struggle with drain cocks which won’t drain?
You could eat your dinner off this top. No dust traps or pipes. That has to be a winner with customers.
Now that is what I call innovation. I have never fitted an indirect cylinder as easy as this.
The electrical connections for the zone valve are clearly marked and if you can place it down at the bottom of the primary flow you can run the cable straight through that channel with no junction box. You could eat your dinner off this top. No dust traps or pipes. That has to be a winner with customers. Now that is what I call innovation. I have never fitted an indirect cylinder as easy as this.

A few months ago I was saying in my blog just how little real innovation there is in plumbing and heating and in response OSO wrote to tell us how they had been busy bringing lots of innovation to their new ‘Super S’ unvented cylinder. It looked good on paper but a lot of things do and I decided that my next unvented cylinder installation should be an OSO. By chance I also happened to be on a completely unrelated training course and met a couple of plumbers who told me they fit nothing but OSO cylinders and had never had the slightest trouble from them.

With 26kw heating coils in indirect units from 150 litres the recovery times are usually below 20 minutes depending on your boiler. Direct units are factory set to heat to 70°C, with a blending valve to bring the DHW down to 60°C on the draw off. This extra energy stored in the direct cylinders allows downsizing for space and cost savings.

The Super S is manufactured using laser welding technology, which requires no filler rod. The welds are created in an oxygen free atmosphere, eliminating the need for cleaning of corrosive oxides on the weld which is typically done by acid washing. That means the Duplex stainless steel starts out with a better chance and not having all that acid also helps the planet.

The very obvious benefit of this design is having all the connections on top which makes life so much easier and if you ever need to get the cylinder out to get at some pipes behind for example or even remove scale from the bottom then it is very easy to do.

The insulated top not only hides all the pipe-work but helps reduce heat loses. You might think that you don’t get much heat loss from an unvented but when I looked up the figures once I discovered that some cylinders lose 3 KW hours per day.
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