Tell me about copper HW cylinders...

[RigidRaider]

Just bought an unused 160 litre cylinder off Eblag. It will go up in the attic in tandem with the existing cylinder for my solar project. May I have the benefit of your experience please?

(Conventional gravity fed system BTW)

I see Screwfix do a blanking plug for the immersion heater hole. Why are there FIVE inlet-outlet bosses and can I also buy a blanking plug for the unused boss halfway up the side?

Full up this will weigh 160 kgs + 18 kgs so 178 kgs plus fittings and I plan to encase it in an insulated box. Is it okay to put this on a board on the rafters or should I look around for somewhere with at least a stud wall underneath for some support?

It will need to be quite near the 1st floor electrics, which are in a messy rat's nest of junction boxes on a board on the attic floor. Are there any regs about proximity to electrics?

Our HW is quite sluggish all over the house, never worked out why, I plan eventually to fit a low boost pump to the showers. Do you think adding this cylinder in tandem will reduce the flow even further?

Finally, what would happen if the loop of pipe out of the top got to within a few inches of the water level in the supply tank? Am I likely to get an airlock and so should I fit a bleed valve at the highest point?

PS: Yes, I plan to test fill the cylinder before heaving it up through the attic hatch! It will be a tight squeeze but should go OK.

 

[Rico99]

Rigid,

On the subject of hot water pressure, where it the cwsc in releation to your existing cyliner.

Rico

 

[Newboy1996]

Firstly, why is your copper cylinder in the attic and not the last floor of your house (usually second floor)? You feed cold water tank for your copper cylinder should be in the attic, flowing water down to the copper cylinder. Are you in a bungalow??
You need ONE copper cylinder with TWIN COILS, one for your gas boiler, one for the solar circuit. Solar should use a pump/controller to get hot water to cylinder, gravity hot water won't work because your solar panel is higher than the cylinder?

Have you got a diagram or a book on solar hot water for guidance, that should be your first move.

 

[gas4you]

Think he means his heating system is gravity primary, not the solar.

Having a pre-heat cylinder for solar is quite a usual and standard way to install solar to an existing system.

 

[Newboy1996]

Think he means his heating system is gravity primary, not the solar.

Having a pre-heat cylinder for solar is quite a usual and standard way to install solar to an existing system.

Using a pre-heat cylinder for a person with little knowledge would be hard to configure and wire!
Simplest way is via a double coil cylinder, using a differential controller. When its too cold the gas boiler will start, if 65+ gas boiler won't!
Does he have a F&E tank and where is it?

 

[RigidRaider]

Thanks for the input. Unfortunately using a twin coil cylinder is not the simplest way because the muppet who built this house installed the cylinder (conventionally on the first floor) then built the cupboard around it! Consequently some of the connections are out of reach! Clever, eh? This is only a small, maybe 90 litre cylinder.

So I have decided to put the bigger cylinder in the attic straight above the existing, in tandem. This is the easy part and I plan to do this now during the current cool weather so I don't sweat my nads off in the roof. That will give us a chance to run it for a few months in case any flow problems show up and need correcting.

My only slight concern with that is that the pipework from the panel and control equipment needs to be as straight as possible so I'm wary of installing the cylinder somewhere silly. Should be okay though if it's under the right part of the roof with the coil inlet & outlet on the correct side.

Next year we will buy the panel from Vridian Solar, it's a nice and simple system with a draining down panel that fits flush with the roof tiles - have a look at their website: http://www.viridiansolar.co.uk/

I don't know what you guys mean by a F&E tank or a cwsc but if you mean the HW supply tank, that's high up in the attic, the water level must be 2-3 feet above where the top of the new cylinder will be. I will put a vent on the cylinder outlet.

To be honest I am doing this with the help of my neighbour, an elderly retired plumber, but I wanted to get your slant on these questions because you gentlemen are still in the business whereas my neighbour, bless him, isn't fully familiar with recent developments in some plumbing technology!

Any more suggestions for possible pitfalls? Thanks.

 

[Registered Gas Man]

Just to get this right

You are heating the H/W in your new cylinder by connecting the coil in the new cylinder to the solar circuit.

Then passing the pre heated H/W into the old cylinder to be heated - if needed - by the boiler/heating circuit.

Not 100% sure how the flow to your H/W outlets will be affected, I cant work out in my own mind where the measurments for your head will be taken from, top of the new cylinder or the old.

Maybe someone can help me/you out.

 

[Newboy1996]

You also have the problem that most of the time water will not reach 65 degrees in your new cylinder. Making a great place for legionella to multiply. If you have ever looking in an old cold water storage tank and seen the black/ green growth. One cylinder, your gas boiler would push it over 65 degrees if needed.
You could still put a single twin-coil cylinder in with what ever arrangment you have, get your plumber to do it for you. Get the plan sorted before chopping into your pipework, it could end in tears!

 

[sooey]

Not 100% sure how the flow to your H/W outlets will be affected, I cant work out in my own mind where the measurments for your head will be taken from, top of the new cylinder or the old.

From the water level in the cwsc to whichever hot outlet is open.