We have recently had a solar installation put in.  Our previous cylinder was a 300Ltr Mains Pressure, 5 yrs old and the water pressure delivered was just great.  Since the installation of the solar the water pressure has been reduced.  I have asked the installer but just keep getting fobbed off with it should be the same as nothing's changed.  Not sure if they put in a new tempering valve but if they did I'd like to know what they did with the previous one (also only 5 years old).  New solar hw cylinder is also a 300 Ltr Mains Pressure.  If we'd have known that the water pressure would have been reduced we wouldn't have bothered going to solar.  Any clues please?

Linkback: https://www.plumbers.nz/solar-heating-and-heat-pumps/9/reduced-water-pressure-after-solar-installation/558/

Hi Blakie, If you installed a new Solar system the installer would have installed a new Tempering Valve! difference is: The new tempering valve is rated up to 110deg (high temperature tempering valve). These valves usually have a strainer attached to the washer. If the installer didn't flush the panels first then a lot of the dust and grit that was inside the panel would have been flushed into those washers. This will reduce the pressure! Just get your installer to crack the unions on the tempering valve and clean out the rubbish. Also to note is make sure you tempering valve suits the hot water pressure. You can get low pressure tempering valves as well.

Regards Plumber

Hi Robbo, can't see anything on the cylinder pipes that looks like a pressure limiting valve in your pic.  I know which is the tempering valve as I have had that one pointed out to me and also the circulating pump.  Just before the tempering valve is another Apex valve of some sort but not same as the picture.

Just listened to a answer phone message from installer who says that he cant understand why the pressure would be reduced as all the valves are the original existing ones.  Hope he's not suggesting that because I am a girlie I'm imagining the pressure reduced.

Also now that I come to think of it I don't think I've heard the pump running for a few days either but that may be something different.  They will come back and have another look next week.  thanks for all the info, I may be back for more.  My mum has a 2 yr old solar, 24 tube, 270 ltrs and the water pressure just about pins you against the opposite wall of the shower!