shower pump pipework

[scoobied64]

Hi there I've just a few quick quetions.

I've got a shower pump to install into a gravity fed shower system - a techflow tp75 - this has 15mm connectors to the pump but the instructions state use 22mm from hot and cold tanks and then reduce before pump - then run 22mm to shower and reduce again. If this has to be done fine but as I already have a 15mm feed from hot tank and 15mm feed from cold I was planning on using this already existing pipework and was wondering if this would be an issue? Also as pump has a push fit connector to pipework does this mean pushfit connectors ok throughout and even plastic pipping........

To be honest even if it was ok I'd rather copper and solder joints but I'm now intrigued

 

[Richard C]

Shower pumps don't suck very well & you should always use 22mm supply from the tanks to the pump to avoid restricting flow, even if the pump connections are only 15mm. Max pre-pump pipe length is also only around 3m for 15mm pipe, it’s around 5m for 22mm. Using 15mm pump feeds may also invalidate the pump warranty. You can reduce to 15mm after the pump but, again, this will restrict flow; it’s not as critical as using 15mm before the pump but shower will work much better in 22mm up to the shower mixer.

Personally I never fit pumps with 15mm connections, only 22mm & I always run in 22mm soldered copper through to the mixer valve. Use full bore isolator valves, bend the pipe & use straight couplers rather than using elbow fittings. I’m a bit of a Luddite when it comes to plumbing, I would never use push fittings or even compression unles I have to on the rest of the system & never, ever use plastic.

 

[scoobied64]

thanks for the reply - it was pretty much as I'd worked out.

 

[scoobied64]

Hi there as a follow up question - looking at the existing connection to the hot water tank I have an essex flange to the 15mm pipework. I presume all I need to do is drain the tank and remove the existing flange and replace with a 22mm one? I would assume that I would need to increase the size of the hole in the tank?
scoob

 

[Richard C]

Obviously drain the cylinder first & check you don’t have a 22mm flange with a 15mm adaptor. If you need to change the flange check the size of the hole as you may need to open it up to suit; I’ve never actually fitted a 15mm so I'm unsure if the flange is the same size or not . Look around for suppliers as you don’t need to pay the fancy prices some quote, particularly if you bend your own internal collector tube. They look a bit daunting to fit but don’t be intimidated by thoughts/stories about dropping bits inside the tank; if you follow instructions & take your time you’ll wonder what all the fuss is about.

 

[looneyfitter]

How long is the run from your storage tank to the pump? As stated, the pumps dont suck very well.

I would give technical a ring and ask for there advice personally.

The other option is to change the pump for a negative head jobbie with 15mm connectors.

BTW it is perfectly fine to use plastic pipework or even a mixture should you prefer. All copper is the best method but it can also be long winded and OLD SKOOL.

HTH

 

[Richard C]

BTW it is perfectly fine to use plastic pipework or even a mixture should you prefer. All copper is the best method but it can also be long winded and OLD SKOOL.

I did say I was a Luddite when it comes to plumbing I also wonder what the service life is for the “O” rings used on push fit.

 

[looneyfitter]

i know mate, I prefer copper but to be honest, nowa days you have to fit plastic to be competative especially on new build. I can 1st fix 3 x 3 bed houses on my own in a day with plastic. Copper and im down to 1.

Most plastic companies give A 25YEAR garauntee.

 

[Charnwood]

Most plastic companies give A 25 YEAR garauntee.

As do the British copper tube (Wednesbury, Yorkshire, Lawton) and fittings manufacturers. Problem being, hardly anyone in the domestic market uses British fittings anymore.

 

[utterlydiy]

I know this was many moons ago.
But I fail to see if 22mm hoses at the pump are any better than that of 15mm, when both hoses use 12mm bore flexible hoses and the swaged plastic fittings both ends have 8mm bore with further flow restrictions ???

 

[dal5band]

If the pump is in the airing cupboard, short runs of 15mm should be ok - this is what I have. It is best to have short runs on input side of the pump and longer runs on the delivery side.