How to diagnose my solar geyser (retrofit)

[alkit]

Hi,
Myself and a friend got solar geysers put in at the same time.
I got a 24 tube retrofit to my existing 200L kwikhot geyser
Friend got a full system - 30 tube 300L.
Both are Apollo systems installed by the same people.
We have set the same timers on both systems.

In my house - it is myself(shower) and the domestic (bath)
Friend's house - Himself (shower), wife (bath), baby (bath)

After a day of sun, my friend's geyser typically reads almost 70 degrees. After a shower and 2 baths, it goes down to mid 60s. By the morning, it is sitting on 60ish (typical sunny winter day)

My geyser - After a day of sun - just under 60 degrees. After 1 shower, it goes down to under 30 degrees!?

So this is what is concerning me:
1) I have theoretically 1.2 tubes per 10 litres of water - surely my geyser at the end of the day should be even hotter than my friend's (who theoretically only has 1 tube per 10l of water)
2) I know my geyser is smaller, but surely the jump in temp after just 1 shower is ludicrous?

Based on the above, my geyser is using around 40kWh per week (as it has to reheat after each bath/shower). Friend's is using 4kWh per week. Insane!

Can anyone suggest what could be causing this?
Could it perhaps be that a retrofit is just significantly less efficient that a full system (this wasn't intimated by the solar installers though)?
Perhaps something has been installed incorrectly on my end? If so, can anyone recommend an experienced installer to come look and see what could be wrong (obviously more than happy to pay the call out).

Thanks!

 

[thehuman]

Try to meusure water coming out of taps
Your systems temperature sensor could be at the element thermostat pocket
When cold water comes into geyser it maybe gets released near element and then gives a false temperature reading
Try to keep element of and see if there is enough hot water

 

[alkit]

Try to meusure water coming out of taps
Your systems temperature sensor could be at the element thermostat pocket
When cold water comes into geyser it maybe gets released near element and then gives a false temperature reading
Try to keep element of and see if there is enough hot water

Thanks for the suggestion, but already ruled that out. I took a shower in the morning (when the geyser was at 50) and by the end of the shower, the water was luke warm (with the cold tap off).
Geyser was measuring 20 degrees after the shower (I assume possibly a little bit of warm water was still ontop of they geyser making it luke warm).

 

[thehuman]

Ours also split system 200l 24 tubes
Fitted February
Peaked 80 degrees in February
Highest temp we get now in winter is 55 degrees
We all bath/shower at night
Normally need to trigger element for 15 mins at moment in winter
I found top of geyser temp is still very hot while temp gauge says 20

 

[bruce_the_loon]

Is there a difference in roof angle and orientation between your installation and your friend's? The angle is critical to gathering heat.

 

[alkit]

Is there a difference in roof angle and orientation between your installation and your friend's? The angle is critical to gathering heat.

Well, they both north facing. Mine is a regular old fashioned tiled roof. As for angle, not really sure, but as far as I've been told, the tubes are a lot less fussy with angles than the flat panels especially in winter.

 

[thehuman]

I am starting to think a split system have some extra losses because geyser below colector

 

[OverKill69]

Hi,
Myself and a friend got solar geysers put in at the same time.
I got a 24 tube retrofit to my existing 200L kwikhot geyser
Friend got a full system - 30 tube 300L.
Both are Apollo systems installed by the same people.
We have set the same timers on both systems.

In my house - it is myself(shower) and the domestic (bath)
Friend's house - Himself (shower), wife (bath), baby (bath)

After a day of sun, my friend's geyser typically reads almost 70 degrees. After a shower and 2 baths, it goes down to mid 60s. By the morning, it is sitting on 60ish (typical sunny winter day)

My geyser - After a day of sun - just under 60 degrees. After 1 shower, it goes down to under 30 degrees!?

So this is what is concerning me:
1) I have theoretically 1.2 tubes per 10 litres of water - surely my geyser at the end of the day should be even hotter than my friend's (who theoretically only has 1 tube per 10l of water)
2) I know my geyser is smaller, but surely the jump in temp after just 1 shower is ludicrous?

Based on the above, my geyser is using around 40kWh per week (as it has to reheat after each bath/shower). Friend's is using 4kWh per week. Insane!

Can anyone suggest what could be causing this?
Could it perhaps be that a retrofit is just significantly less efficient that a full system (this wasn't intimated by the solar installers though)?
Perhaps something has been installed incorrectly on my end? If so, can anyone recommend an experienced installer to come look and see what could be wrong (obviously more than happy to pay the call out).

Thanks!

There is a difference between retrofit and full system:

The retrofit system uses a small solar pump to continually cycle water through the solar manifold. The full system has the solar manifold directly heating the water in the geyser. So the retrofit geyser heats up very gradually.

So you have to understand the way the system works and where the energy goes.
The retrofit geyser will heat up slowly, and it'll cool rapidly when hot water is drawn and replaced with cold water. So you have to think of "maintaining temperature" as opposed to heat heat heat.

This can be mitigated with how you set your timer.

For example... Let's assume a shower is needed in the morning, and then baths and showers again at night...
Timer could be set from 4am to 11am - This ensures hot showers in the morning, and will keep the water warm until the sun is doing the business.
Then, set the timer to heat again from 4pm to 6pm - this ensures hot water for the evening period. Geyser might be cold overnight, but the morning stint will heat it again.

The full system heats a hellova lot faster because the tubes heat the water directly in the geyser. So if hot water is drawn and cold water rushes in, it can be be heated relatively rapidly. The timer only really needs to cover that morning period. The evening bathing stint will cool the geyser down and the sun isn't out to heat the geyser again... so setting the timer for an early morning start to have hot water for the morning, Then the sun takes over during the day for the evening period.

Ours also split system 200l 24 tubes
Fitted February
Peaked 80 degrees in February
Highest temp we get now in winter is 55 degrees
We all bath/shower at night
Normally need to trigger element for 15 mins at moment in winter
I found top of geyser temp is still very hot while temp gauge says 20

This can be mitigated by installing a "diffuser" into the return from the solar manifold. What this does is introduce the hot water into the bottom of the geyser so it heats the entire volume as opposed to the hot water all sitting at the top.
All it is a smaller diameter pipe inside the 3/4 inch pipe going from top of the geyser to the "bottom middle". In the retro systems the original "HOT OUT" becomes the "HOT IN" and the new hot water out comes out the old safety valve (replaced by a banjo valve). Without the diffuser, the hot water goes in the top, and stays at the top... making a mini thermocline.

 

[thehuman]

Our system have a controller and a 220v pump
Lower temp was today
Higher temp was in February