I am going to attempt to install an intergral power shower and would appreciate some help.
To get the best possible gravity fed flow from hot and cold tanks should I run 22mm pipe and only reduce to 15mm prior to the connections to the unit?
For the cold I will take a dedicated supply from the tank on the opposite side to the ball valve. How is it best to make the hole in the plastic tank and how how do I get the diameter of the hole exactly correct for either a 15mm or 22mm outlet?
The instructions say I should use a "full way isolating valve" on the hot and the cold. Is there something in the speedfit plastic range that will do this job or do I need to insert something with a compression fitting?
You should use 22mm to the pump for both H&C.
Use a hole cutter to form the hole in the tank (empty tank first!), pick a point about 50mm up from the base of the tank on a flat section with no bracing behind it.
Use full flow isolating valves - compression type are fine.
If by"integral power shower" you mean a shower with an integral pump then you will be pumping both h&c supplies
If you are pumping it makes little difference whether its in 22mm or 15mm. The different flow rate between the two sizes of pipe only really comes into play when you are solely gravity fed with no pump.
Full way (full flow) = full bore in my terminology. That means a valve which does not restrict the flow of water. Standard 15mm isolating valves reduce the bore down to about 7mm which cuts flow drastically.
Are you fiting the appropraiet flange to yout hot water cylinder so that you get separate supply to the shower from the remainder of your system?
Yes the shower unit and pump are all in one box which will be mounted on the wall above the bath.
The hot water feed will be the first supply from the tank output before the vent tee. Should I keep this pipe run at as low a height as possible or is it ok to run it up into the loft and then down into the bathroom and into the top of the shower unit?
IMHO you should have a separate hot supply from the rest of your taps for the same reasons you are putting in a separate cold supply. Fit a Surrey, Warix or Deleted flange to the cylinder to provide that separate supply.
Yes you can run the pipework through the roofspace.
"Sorry but I don't understand. There are no additional unused outlets from the copper hot tank. How would I install such a flange as you suggest."
A Surrey or Warix flange fits in the top of the tank at the 1" BSP connection. The Surrey has a spigot which goes down into the tank below the level where air normally accumulates and provides an air free supply for your shower which can easily be pumped. This supply comes out of the flange at 90 degrees to the normal output. A second output on the top of the flange is connected to the (slightly shortened to accommodate the flange) vent pipe in the normal way with the hot feed for taps teed off that. The Warix is similar but the position of the 90 degree output can be adjusted after the flange is screwed into the tank. Both have a 1" male BSP connection for a female tank. If the tank has a 1" male connection then there is a variant of the Surrey (called a Yorkshire) which has a female connector on the bottom.
Finally the E s s e x is either fitted to a secondary boss on the side of the tank below the dome or if one is not fitted (as in your case) the the tank can be cut to fit one. Cutting the tank is not a job for the faint hearted as there is a real risk of damaging the tank. I'd suggest you go for the Surey/Warix/Yorkshire whichever is appropriate for your installation.
I've decided I am going to replace the direct vented hot water tank at the same time as it is very old.
Are the connections into the tank - Surrey Flange - Cold Input - and Immersion Heater effectively just screw in connections / compression or is it a bit more complicated than that. Is any sealant required?
Also my current immersion heater (which I will replace) goes into the top of the tank and has two different length elements. There is a switch on the exposed part of the immersion that enables you to thus choose from heating the whole tank or just the water at the top. Is this how they still work now or do you have two separate immersions going into the side of the tank?
"Are the connections into the tank - Surrey Flange - Cold Input - and Immersion Heater effectively just screw in connections / compression or is it a bit more complicated than that. Is any sealant required?"
Yes they are screw in. You'll need an immersion heater spanner. Use some jointing compound on the threads of each connection.
"Also my current immersion heater (which I will replace) goes into the top of the tank and has two different length elements. There is a switch on the exposed part of the immersion that enables you to thus choose from heating the whole tank or just the water at the top. Is this how they still work now or do you have two separate immersions going into the side of the tank?"
Yes you can get dual element heaters suitable for fitting in a single immersion heater boss.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!