Home Solar Hot Water - Timer question

[dazzler]

Howdy

Our new place has solar hot water and solar power panels as well as two huge gas bottle for cooking.  (Apparently each bottle lasts over a year).

Being winter, or as winter as it is up hear, the previous owner advised that we may need to use the electric booster at times.  Being a large family that makes sense.  So we have run it the past week and it seriously eats up the power / $$.

From a brief trial with the boost off it looks like we have enough of an evening however in the morning the water is cooler. Still warm enough though I wonder how it will go when we are all back at school / work / uni etc.

There is no point heating it up after say 8pm so is it possible / safe / recommended to use a circuit breaker with a timer on it so that it comes on at say 5am for the morning showers? 

Would this actually reduce power use?

The other option is to install a gas instant hot water service running off the gas bottles and have that feed in when the solar water is too cold.  Our ensuite is next to the gas bottles so I could cut that out of the system and have that always on gas so we can leave the solar alone and if its cold then the kids can use the ensuite.

Am I just being a scottsman and will the feed in tariffs equalise out over the year.  So the $$ spent now paying for the power for the solar come back to us as power sold to the grid in summer?

Thoughts from anyone on solar?

[jetcrew]

dazzler,

i also have solar hot water with a elec booster .

In summer i find that i can have the booster switched off this is for about 9 mths in SEQ.

In wi8nter as per now my booster is ON.. the prob is the boosters are set to normal tariff..

These systems are designed to heat the water via solar during the day... the issue is that when you shower at night ..with boost off ..you take the hot water out and it then fills with cold water ..with no boost or sun it sits in the drum all night and is very cold by morning .

So you either need to limit usage to nights only to allow water to heat next day or use the boost. But i like a morning shower

I am going to spaek with my sparky about putting my boost to off peak..prob with this is no solar credits on this tarriff ..so realloy its hard one.

I just leave boost on for the 3 mths and then have it off for the other 9.


jET

[D4D]

I recently replaced our solar HWS because of this challenge/issue. We now have a Rinnai natural gas continuous HWS. Gas bill has increased by a small amount but the electricity bill has dropped heaps. Now we have steaming hot showers in the morning, make sure you get the 60 degree model.

[jetcrew]

I recently replaced our solar HWS because of this challenge/issue. We now have a Rinnai natural gas continuous HWS. Gas bill has increased by a small amount but the electricity bill has dropped heaps. Now we have steaming hot showers in the morning, make sure you get the 60 degree model.

when my solar unit dies i will also be going the gas route. The elec booster kills the advantage of the solar as 200ltrs is not enough sometimes and with boost on full tariff it might actually be cheaper to run a bigger elec only  unit on off peak for the winter period.. but the payback is during the other 9 mths when my hotwater is supplied from SOLAR ONLY ..

Everything has it good and points .. but solar in colder climates not sure i would be a fan..

jet  

[Nomad]

Could you use a Rinnai to boost through winter, given it has an auto or remote temp control.

I have only ever used a Rinnai in the homes I have built and find them brilliant.

Cheers Nomad.

[Jenko67]

We have a solar rinnai with gas booster... Works perfectly....

[Spada]

I recently was looking at replacing our solar hot water for the exact same reasons, but instead I did some checks, spent $110 dollars, and now have hot water in the morning.

This will only be relevant if your house was plumbed after tempering valves were mandated.

What is a tempering valve you ask ?       well there are 2 conflicting laws that apply to hot water. Stored hot water must be maintained at above 60 degrees to kill legionella bacteria, but by law can not be supplied to a tap used for bathing above 50 degrees (45 for childcare centres / nursing homes etc), so a tempering valve is plumbed into the water line that feeds the bathrooms. The tempering valve is a 3 way mixer that that has a hot in, cold in, and mixed warm out. It has a valve that works like a car thermostat, and they have about a 10 year lifespan.

in the morning, check the temperature of the hot water at your kitchen tap (which should be direct from the solar system), and then check the temperature at the shower (which will be via the tempering valve). If the kitchen is hotter than the bath, chances are the tempering valve is cactus. $110 from the hardware (make sure you get one rated for solar) should fix it.

If both the kitchen and bath are the same, then you will need to consider other heating options like using the booster. You could try having the solar system serviced which will involve cleaning the panels, changing the glycol, and checking the thermostat. That will cost you about $300.

Hope the info is of some use.

[rags]

I recently was looking at replacing our solar hot water for the exact same reasons, but instead I did some checks, spent $110 dollars, and now have hot water in the morning.

This will only be relevant if your house was plumbed after tempering valves were mandated.

What is a tempering valve you ask ?       well there are 2 conflicting laws that apply to hot water. Stored hot water must be maintained at above 60 degrees to kill legionella bacteria, but by law can not be supplied to a tap used for bathing above 45 degrees, so a tempering valve is plumbed into the water line that feeds the bathrooms. The tempering valve is a 3 way mixer that that has a hot in, cold in, and mixed warm out. It has a valve that works like a radiator cap, and they have about a 10 year lifespan.

in the morning, check the temperature of the hot water at your kitchen tap (which should be direct from the solar system), and then check the temperature at the shower (which will be via the tempering valve). If the kitchen is hotter than the bath, chances are the tempering valve is cactus. $110 from the hardware (make sure you get one rated for solar) should fix it.

If both the kitchen and bath are the same, then you will need to consider other heating options like using the booster. You could try having the solar system serviced which will involve cleaning the panels, changing the glycol, and checking the thermostat. That will cost you about $300.

Hope the info is of some use.

 Being in the plumbing industry  I may add a few corrections, the temperature to bath shower basin should be a max of 50deg unless disabled which is 45deg controlled by a thermostatic mixing valve [TMV],Your check to see if the valve is a cactus may not work as the whole of house maybe plumbed through the tempering valve including the kitchen [ easy to see as the non tempered line will branch off before the tempering valve ] typical on project type homes and with solar systems as you can otherwise experience uncontrolled temperature rise. But as Dazzler said the issue is the temperature on a winter night, so would not be related to the tempering valve.
Dazzler you may wish to consider a offpeak booster but will involve new metering which will cost and then only heat in the off peak period. The option of a rinnai type heater may be a good option but the LPG price would need to be factored. There would be 3 options with going the gas booster, 1 a package solar/ gas unit, with water temperature sensors to divert the water thru gas unit if water temp not hot enough, 2 a set up where the hot water passes thru the gas heater regardless of temperature,but will only raise the water to required temp, so may not be doing to much heating in summer, 3 a manual system where you would create a diversion with the use of  a couple of valves, that you only divert if you think the water needs additional heating , oh a 4th option as mention save the solar system for the main bathroom and house use and have a gas unit for the ensuite, but then you would  be using gas year round although you could incorporate option 3 into this system.

[dazzler]

Thanks everyone for your valuable input.

Though Rags I am VERY disappointed in your response.  I thought a few giggly plumbers terms would have been used to lighten my mood before bed. 

You know the stuff .....

You will need a water cock.

Some sort of flange.

Don't hold out on me...

[oldmate]

Thanks everyone for your valuable input.

Though Rags I am VERY disappointed in your response.  I thought a few giggly plumbers terms would have been used to lighten my mood before bed. 

You know the stuff .....

You will need a water cock.

Some sort of flange.

Don't hold out on me...

Maybe some ky 

[Supersi]

I recently replaced our solar HWS because of this challenge/issue. We now have a Rinnai natural gas continuous HWS. Gas bill has increased by a small amount but the electricity bill has dropped heaps. Now we have steaming hot showers in the morning, make sure you get the 60 degree model.

X2

Although Rags ideas are good!  I didn't have that option as my solar panels died.

[Homer_Jay]

We have a solar hot water. It is old and not very efficient.
I had the sparky wire up a timer in the meter box (thing it was $80 or so plus labor iirc).

I have it set to come on for 1/2 in the mornings and 1 hr in the afternoon. Always have hot showers and doesn't hurt the power bill too much.

Before we had the timer, we would always turn the booster on to heat the water and would forget it was on, so hence the power bill took some pain.

Wouldn't be without the timer now.

[xcvator]

There is another solar hot water system that will work 24/365, but you need a bit of space and enginuity  You will need 2 or 3 banks of evacuated solar heating tubes and about a 1500 litre sealable tank ( probably made from 100mm cool room panels ) the tank is filled with water that is fed through the heating tubes via a control panel that turns the flow on and off depending on the temp in the tank( idealy 60c). Entering the tank you have a coil of approx 30/40 metres of 20mm tube that carries in the cold water which is heated from the coils immersion in the hot water, the water exits from the coil at about 45c.
With no sun for 3 days the water temp in the tank will drop about 3c so you don't need a booster.
Increase the size of the tank to 2500/3000 liters and you can add hydonic heating to your house as well, just need a 2nd controller unit, this excercize can be done for about $2000/$5000 

[Alan Loy]

There is another solar hot water system that will work 24/365, but you need a bit of space and enginuity  You will need 2 or 3 banks of evacuated solar heating tubes and about a 1500 litre sealable tank ( probably made from 100mm cool room panels ) the tank is filled with water that is fed through the heating tubes via a control panel that turns the flow on and off depending on the temp in the tank( idealy 60c). Entering the tank you have a coil of approx 30/40 metres of 20mm tube that carries in the cold water which is heated from the coils immersion in the hot water, the water exits from the coil at about 45c.
With no sun for 3 days the water temp in the tank will drop about 3c so you don't need a booster.
Increase the size of the tank to 2500/3000 liters and you can add hydonic heating to your house as well, just need a 2nd controller unit, this excercize can be done for about $2000/$5000 

Is this a DIY or does someone sell this system?

[jetcrew]

We have a solar hot water. It is old and not very efficient.
I had the sparky wire up a timer in the meter box (thing it was $80 or so plus labor iirc).

I have it set to come on for 1/2 in the mornings and 1 hr in the afternoon. Always have hot showers and doesn't hurt the power bill too much.

Before we had the timer, we would always turn the booster on to heat the water and would forget it was on, so hence the power bill took some pain.

Wouldn't be without the timer now.

I was thinking of getting the elec to wire in a switch in the ensuite with a red light on it, switch boost on and light is red .. this way i can control the boost from in my ensuite and the light indicates its on ..;as like you i throw the breaker and then forget to flick it back off/on.

I would say the boost has added 3Kw per night to my power bill = $0.90 a day for the 90 days of winter = $81 per year for hot water still not bad 

Jet



Jet

[Spada]

Being in the plumbing industry  I may add a few corrections, the temperature to bath shower basin should be a max of 50deg unless disabled which is 45deg controlled by a thermostatic mixing valve [TMV],Your check to see if the valve is a cactus may not work as the whole of house maybe plumbed through the tempering valve including the kitchen [ easy to see as the non tempered line will branch off before the tempering valve ] typical on project type homes and with solar systems as you can otherwise experience uncontrolled temperature rise. But as Dazzler said the issue is the temperature on a winter night, so would not be related to the tempering valve.
Dazzler you may wish to consider a offpeak booster but will involve new metering which will cost and then only heat in the off peak period. The option of a rinnai type heater may be a good option but the LPG price would need to be factored. There would be 3 options with going the gas booster, 1 a package solar/ gas unit, with water temperature sensors to divert the water thru gas unit if water temp not hot enough, 2 a set up where the hot water passes thru the gas heater regardless of temperature,but will only raise the water to required temp, so may not be doing to much heating in summer, 3 a manual system where you would create a diversion with the use of  a couple of valves, that you only divert if you think the water needs additional heating , oh a 4th option as mention save the solar system for the main bathroom and house use and have a gas unit for the ensuite, but then you would  be using gas year round although you could incorporate option 3 into this system.

Thanks rags for the more informed responce.

I was having luke warm showeres, even with the booster. Then the penny dropped one morning when I was making my coffee that the kitchen tap was too hot to put my hand under.

I replaced the mixing walve, and now I havn't used the booster at all this winter (SE QLD).

[WilSurf]

Our house has the same system: solar hot water with electrical boost.
We switch it off during the day but then the water isn't hot enough.

[muzza01]

I know our climates are very different but this is how it works for us. Our solar works well in the summer months for warm showers for a family of five (when my oldest son and his girlfriend stay at our house).  If we have overcast weather and rain we will hit the boost switch prior to going to bed.
During winter (yes in Cairns) we have a lot of sunny days but I find that people have much warmer showers therefore use more hot water.  There is always enough hot water for our family of three but if my son and future daughter in law stay over the usually the water starts to run out when the last person has their shower.

We also have the two big gas bottles for our stovetop. (The oven is electric) one bottle normally lasts us around 14-15 months.

[Rob C]

We had a Solar hot water installed a couple of years ago and being an Electrician I also installed a Solar Booster timer to the system.
It works like this, most of the year it is turned off using an isolator switch. When required we turn on the switch press the booster relay and either let it go till it reaches temp and the thermostat cuts out which then drops out the booster relay(and will not come back in until it is pressed again) or we time the booster and turn of after 1 hour which generally is enough for hot showers for the next couple of days.
Works for us and still quite cheap to operate.

Rob.