solar hot water problems?

[Tim86]

Hi, im wondering what other peoples experience with solar hot water systems is?

Ive got a one month old 315l evacuated tube apricus system. On 25 degrees days facing north with full sun and it will only heat water to 40 degrees and that runs out within 10 mins of having a shower. With the booster on in the same conditions it will run out of hot water within 40 mins of showering.

For a system that cost $4350 installed im pretty unhappy with it. Ive had techs come and tell me to leave the booster on 24/7 all winter. I did that and i still run out of hot water within 40 mins even on 25 degree sunny days.

Is this just to be expected with these systems?

 

[Xjas]

How long the hot water lasts really depends on the water flow rate of your shower, how hot the hot water system is heating to,how cold your cold water is and how hot your showers are. All are easy to measure and then calculate to give you a rough estimate of available shower time.

As an example:
If you have 40C showers, your hot water heats to 75C, cold water temp is 20C, using a 9L/min shower head.
Then 36% of your shower water is hot water, calculated using:
http://www.spiraxsarco.com/au/resources/calculators/water-mixing.asp

That give a total of 875L of water output at 40C.
875L divided by 9L/min is a total of 97 minutes of shower time if you dont use hot water for anything else.

 

[Pa1nter]

Perhaps you need to top up the water level with the relief valve.
I have seen this happen many times.

 

[Tim86]

Perhaps you need to top up the water level with the relief valve.
I have seen this happen many times.

Thanks for the replies. Ill have a look at all the temps when i get home with the booster on. The install is brand new so the tank has only just been topped up.

Ive contacted simply solar asking for a refund because it doesnt do its job and they said no... So i guess i get to ring up apricus again and ask their technician why im still running out of hot water even with the booster on.

 

[Deena]

I can't comment on your system, just give you my sympathy.

I am pretty fed up with my gas boosted system, had minor problems fixed multiple times over the years, and once again I have no hot water. Whilst everyone else have hot water systems with no problems.

My next system will not be any form of solar hot water.

 

[tj22]

Perhaps you need to top up the water level with the relief valve.
I have seen this happen many times.

I have no idea what you would mean by this as the relief valve reliefs pressure from the how water storage unit :s

 

[Scott No Mates]

Sounds to me like they have connected the unit incorrectly - typical $#%k up.

From memory the take off should be at the top of the unit and the cold inlet at the bottom (don't quote me on that) but it is essential that they are hooked up correctly otherwise it is drawing cold water out of the system.


Refer to Ch 2

 

[tj22]

Hi, im wondering what other peoples experience with solar hot water systems is?

Ive got a one month old 315l evacuated tube apricus system. On 25 degrees days facing north with full sun and it will only heat water to 40 degrees and that runs out within 10 mins of having a shower. With the booster on in the same conditions it will run out of hot water within 40 mins of showering.

For a system that cost $4350 installed im pretty unhappy with it. Ive had techs come and tell me to leave the booster on 24/7 all winter. I did that and i still run out of hot water within 40 mins even on 25 degree sunny days.

Is this just to be expected with these systems?

It would be a bad installation i would think. so the booster being a gas continuos flow hot water unit is attached to side of the storage hot water unit?

 

[Tim86]

Looks like the problem was on my end with the pump lead being plugged into a power board that had tripped due to the rain the other day getting into it. So the solar part of the tank wasn't actually working that day.

I still kind of think it's rubbish though that I spent more money for a unit that the sales people told me would work really well in cold climates, only to be told by their technician that you will still need to put the electric booster on 24/7 during winter.

But I've probably just got unrealistic expectations of it. But high price usually goes hand in hand with high expectations...

 

[Doovalacky]

We had solar for many years and it was one of the older styles that was less efficient.

Running it 24/7 with the booster is pointless as it negates any advantage of the solar panels.
At most you should have to turn it on for about an hour or 2 before use to get it up final temp. As a sparky I set it up with a timer to make it simple and limit time it was on.

Spring and Autumn we never needed the booster with a family of 5 unless it was overcast/rainy, and in summer the unit had to be covered with light shade cloth to prevent it from constantly boiling.

40mins is a bloody long shower and even a 315L gas unit will struggle with that if you have high flow shower heads.

 

[Perp]

Running it 24/7 with the booster is pointless as it negates any advantage of the solar panels.
At most you should have to turn it on for about an hour or 2 before use to get it up final temp. As a sparky I set it up with a timer to make it simple and limit time it was on.

Spring and Autumn we never needed the booster with a family of 5 unless it was overcast/rainy, and in summer the unit had to be covered with light shade cloth to prevent it from constantly boiling.

Aren't they smarter at regulating the temperature than this? Surely the booster is linked to a thermostat, and only comes on when needed?

I ask because we're building a new PPOR, and I was planning on installing solar hot water, but not if it's this "unintelligent".

 

[woz]

Im a plumber and have installed a couple of these in the canberra region. They work a treat here.

Reading the start of the thread I instantly thought check the circulating pump though you have seemed to figure that bit out.

The way the boosters work is like perp said. On a thermostat.

The water, via the pump is circulated through the tank and tubes thus heating the water in the tank. The tubes will heat the water faster then the booster which is there for cold miserable days and nights if youve drained the tank.

Is the elec booster on off peak? If so it wont be doing much, if anything at all for you recovery in mornings / evenings if you have used the hot water which is why I recommend the gas boosters.

Itd take a few hours to recover 315L on the elec booster if its outside of daylight hours being able to utilise the tubes. After all its a storage hot water system, not continous flow hot water. Once the hoot water is gone, unless its a commercial fast recovery gas storage unit itll take a few hrs to heat up again.

Now that youve sorted the pump issue out it should be working properly now though

 

[woz]

The elec booster should be left on 24/7. Now the pump is working, its using the tubes to heat. And they are very efficient at it. The booster just keeps the water at say 70 degrees.

The tubes will heat that easily on nice winter days. Come cooler days /nights the booster will just top up the heat. Say the tubes can only get temp to 60 on cooler days, the booster will get it to 70 then turn off. Once it drops down to 65 or so itll turn on and top up again to 70.

This will even happen in summer. If 5 people shower at night and drain the tank it will heat up again for the morning before the tubes take over

 

[Perp]

The way the boosters work is like perp said. On a thermostat.

The water, via the pump is circulated through the tank and tubes thus heating the water in the tank. The tubes will heat the water faster then the booster which is there for cold miserable days and nights if youve drained the tank.

Is the elec booster on off peak? If so it wont be doing much, if anything at all for you recovery in mornings / evenings if you have used the hot water which is why I recommend the gas boosters.

Phew, thanks woz, great input to have.

I am pretty committed to always having ample hot water, so my inclination was towards a gas-boosted solar unit, but we don't have mains gas, and so I'd have to get LPG tanks. In Brissie, do you think that effort is worthwhile, or would we generally need the electricity so rarely that elec-boosted is adequate?

Is there any, or any significant, up-front price/installation differential between elec-boosted and gas-boosted solar HWS?

 

[bbmick]

I have Solar with LPG Instantaneous as backup. Never run out of hot water, no matter how long the shower (assuming I don't run out of gas).

It's great in Summer - no gas used, even with 6 ppl using - incl a couple of wallies.

Once Winter sets in down Melb way, it's purely on gas.

I love it compared to our old system which was purely LPG.

 

[woz]

As bbmick said in warmer months you will very rearly use any gas. Being in qld the amount of times u need it boosted would be trivial imh.

Could have 2 x 45kg bottles onsite so yrs and not use much. Piece of mind though

So in that respect maybe elec is way to go. Save cost of renting bottles (assuming there is that cost up there)

Colder climates.. definatly gas booster. Especially as someone mentioned on here, the ones which have a continuous flow gas booster. Never run out of hot water in winter and not use and gas in warmer months

 

[Perp]

Could have 2 x 45kg bottles onsite so yrs and not use much. Piece of mind though

I own a couple of bottles as I previously had a gas cooktop (though changing to induction for new house), so no big drama having gas.

Apart from gas providing hot water faster if the sun fails to provide, is there any significant cost differential in purchasing the units up-front, or in maintenance? (Between gas-boosted and elec-boosted.)

 

[woz]

Ill have to get back to you on price of the units.

Both will be very similiar in cost to install

Maintenance wise id suggest elec is cheaper and easier to fix. Only 2 parts in an elec system. A thermostat and heating element. Prob cost about $350 inc labour, materials and gst.

Gas storage booster (not instantaneous) basically only thermocouples go in them. (Safety device which turns gas kff if pilot light goes out) that would be say 120 inc l, m, gst.

Instantaneous booster. These are trickier as have more parts and electrical boards though very very rearly do things happen to them. In saying that the cost if something does go wrong can cost quite a bit more yet a heap is covered by warrenty.

You shouldnt really have a prob with things for the first 2 options for around 7 odd yrs. Option 3 id put it up to 10+ so if you break down those costs over that time its not much at all

 

[Perp]

Thanks, woz. I like the idea of instantaneous gas boost. Mmmmm...

 

[woz]

Itll cost a little more to buy but it would def be my choice / recommendation.

Luxury of not running out plus tubes to reduce costs dramatically.