Free hot water with a solar water heater

[Zasso Nouka]

This might be useful for someone in the future. Our water heater sprung a leak last week where the vacuum tubes enter the tank, the repair is quite easy. You are going to need a 22mm socket spanner, maybe an impact driver, some silicone heat transfer grease and a small-ish file and some of these



No idea what they are called but presumably MMC sell them, the guy that fitted our tank ordered them from MMC. The black one is the old one that corroded through at several points, the shiny one is the new one and the pack above are how they come.

First cut off water supply and then remove the vacuum tube where the leak is, may need to spray the cup holder with silicone spray to loosen it. Store the tube somewhere safe out of the sun or the copper tip is going to get really hot and you won't be able to apply the silicone heat transfer grease. There will be a silicone grommet covering the 22mm nut inside where the vacuum tube meets the tank, take this off and unscrew the 22mm nut, may need your impact driver for this bit if there is some mineral buildup. Insert the file into the receptacle, or whatever it's called and rotate to free it up (you use a file because it's rough edges will grip the receptacle and allow you to rotate it free), water pressure will then pop it out and insert the new one and secure it with the 22mm nut. Use your 22mm socket wrench to tighten not your impact driver, this should be done slowly and cease as soon as there is no longer any water dripping. Turn water supply back on and refill tank, if water starts dripping tighten up the 22m nut a little more until it stops dripping but don't over tighten.

Apply silicone heat transfer grease to your vacuum tube and shove the silicone grommet back in place then re-insert the vacuum tube, tighten up plastic cup holder and the job is done. Open up the pressure relief valve on the top of the tank to allow any trapped air to escape and you should be good to go.

[Zasso Nouka]

Here are some pictures of the file used to remove the 'receptacle'



And with the file pushed into the 'receptacle'



Hope that makes things a bit clearer

[vapidspants]

Perhaps a silly question, but could a solar water heater be hooked up to an outdoor pool? I guess I am thinking of an outside onsen, but without having to do the excavation or expensive digging to reach geothermal water.

[gonbechan]

[Zasso Nouka]

Had to replace some more of the little "heat transfer caps" yesterday as they had corroded through.



So, we removed the effected tubes



Cleaned the ends up with alcohol and wire wool and re-applied the silicone grease



This has to be done in the shade or those copper ends will get really hot.

It's probably a good idea to replace all of the caps once they start corroding but as it was so sunny yesterday I couldn't release enough of the vacuum tubes before the copper tips were getting really hot. Another pro tip, do this job on a cloudy day as the remaining tubes heated up the water in the tank and I had scalding water dripping on my fingers while taking out the old caps (yes, lessons have been learned ). If you aren't replacing all of the caps at once it's probably worth either noting down which ones have been replaced or marking the tank.



As before after putting the new caps in and tightening the 22mm retaining nut open the inlet tap and check there are no leaks before re-inserting the vacuum tubes. By the evening the tank temperature has risen back to around 60C so all set for a hot bath without using any gas to heat the water up.