Gas Boosted Solar Hot Water

[an3_bolt]

Renovating an old house and would like to purchase a gas boosted solar hot water system to replace the old electric one.

I was thinking of something like the Rinnai Sunmaster System 4 (215 litre tank and the infinity 26). We have 4 people total in the house (ma + pa and the 2 kids). Has anyone used this one before or would they recommend a particular system? Would a 215 litre tank be enough or has anyone had experience with this size?
Is there anywhere in particular in Sydney that has competitive pricing on these split systems?

Thanks for any advice or experience you might be able to share.

[Brickie]

We have a roof mounted 315 litre elec solar hot water system, I know that the gas ones boost as they are drawn from and are different to an elec system.

Ours runs out of hot water on consecutive cloudy days and we have to turn on the off peak water heater.

Most of the year we dont have the elec booster on at all.
It doesnt save that much in power bills as the off peak power is way too cheap, but it saves greenhouse gases.

Ours is a 3 panel job, we got the extra panel as a sweetener with the deal when we bought it..

[an3_bolt]

Thanks Brickie

Out of interest - how many people daily using the hot water?

[Brickie]

Thanks Brickie

Out of interest - how many people daily using the hot water?

3 adults, but the boy takes as long as 2 or 3 adults, he has to look pretty you know..

[ptrott]

Have you considered a Heat Pump system?

I did days of research and came to the conclusion that the heat pump was the best option for me. I am 200Km south of Perth, so a bit less sun that Perth.

System cost $3550, getting $1000 rebate for replacing electric system, plus another $1200 back from selling the RECs. so total cost was $1350.

It has been in for a couple of weeks. There are just 2 of us in the house.
We turn it on every second day and it runs for about 2.5 hours then cuts out. (set to 60 C.)
(Water at the end of the second day is too hot to hold your hand under)

That works out at 183 days a year, times 2.5 hours is 457 hours running time.
It uses 1.3Kw so uses 595Kw hrs at 13 cents per Kw Hr equals $77 per year.
That is WINTER figures used for all year round, so it will obviously cost less than that in reality.

A LPG gas instant system uses 1 bottle of gas per year just to keep the pilot light going (according to the guy who sells the gas ones) and at $110 per bottle for LPG it means that I get all the hot water for less than the cost of running the pilot light.

I also have no panels on the roof, just a neat cylindrical HWS next to the house plugged into a standard 10 amp GPO. (No glass to get busted by hailstones, or to clean dirt off, as well as not having to brace the roof supports)

If you are using Natural gas then you would be paying less for your pilot flame, . EDIT, you stated gas boosted, I,m tired)

Something to have a think about maybe??

[Smurf]

Agreed about the efficiency of heat pumps but I'm puzzled as to why you'd want to turn it on only every two days?

If your aim is to cut greenhouse gas emissions etc then I can see the benefit in a timer (or manual switching) to avoid running at peak electricity demand times.

If your aim is to minimise the cost then, if you have off-peak or some form of time of use power charging, then I can see the point in running at the cheaper times.

But running only every second day? I can see that you will save a little bit of heat loss from the tank but it wouldn't be that much surely?

[montiee]

But running only every second day? I can see that you will save a little bit of heat loss from the tank but it wouldn't be that much surely?

I haven't turned my booster circuit on for months. Why anyone would want to turn on the booster every second day is beyond me. Just make sure you get a large enough tank and enough panels (I have 2 large ones on the roof) to cover your daily needs and forget about powering it except on the rare occasion of going without sunlight for 3+ days straight. On those rare occassions I just flip the switch before I go to sleep and turn it off when I get up and I'm good to go for another few days without sun. Any amount of sunlight is usually enough to heat the water just fine. It's just a matter of installing the right amount of panels and tank size for your needs.

[ptrott]

Agreed about the efficiency of heat pumps but I'm puzzled as to why you'd want to turn it on only every two days?

The reason for turning it on every second day is that it simply does not need to be turned on every day. I just don't go around there every day.

If your aim is to cut greenhouse gas emissions etc then I can see the benefit in a timer (or manual switching) to avoid running at peak electricity demand times.

We don't have off-peak power, so I run it during the hottest part of the day, usually around mid-day to early afternoon. This way it can utilize the hotter air and run for less time. If I just left it on all the time and the water temp dropped to the point where it switched on in the early hours of the morning when it is 5 degrees, then it would run for a lot longer so use more power.

If your aim is to minimise the cost then, if you have off-peak or some form of time of use power charging, then I can see the point in running at the cheaper times.

Don't have as stated.

But running only every second day? I can see that you will save a little bit of heat loss from the tank but it wouldn't be that much surely?

Probably save very little if any by turning on every second day, but as I said, I just don't go around there every day. I will be putting it on a timer so it will be on every day during the hottest part of the day as I don't know of any timers that can select days.

[ptrott]

I haven't turned my booster circuit on for months. Why anyone would want to turn on the booster every second day is beyond me. Just make sure you get a large enough tank and enough panels (I have 2 large ones on the roof) to cover your daily needs and forget about powering it except on the rare occasion of going without sunlight for 3+ days straight. On those rare occassions I just flip the switch before I go to sleep and turn it off when I get up and I'm good to go for another few days without sun. Any amount of sunlight is usually enough to heat the water just fine. It's just a matter of installing the right amount of panels and tank size for your needs.

I think Smurf is talking about my Heat Pump, not the O.Posters solar booster.

[Smurf]

I think Smurf is talking about my Heat Pump, not the O.Posters solar booster.

Correct.

[rhancock]

The Permaculture Forum is full of useful information on this topic (and many others).

[an3_bolt]

I am specifically interested in the gas boosted system due to the claimed efficiencies - ie the solar hot water is stored in the tank and the water exiting the tank is only boosted if it is less than a set temp ie the water in the tank is not heated by the gas water heater - only the water in the pipe exiting. I understand that this is different from the electric boosted systems.

Has anyone had experience with the Rinnai series - either the Sunmaster or the Beasley? I have come to understand that a bigger storage tank could be better to minimize any unnecessary gas boosting due to excessive hot water use. Say a 270 litre tank or so - would this be correct?

Cheers

[an3_bolt]

Does anyone actually have a gas boosted solar hot water system that would be willing to share their experiences?

[dzcook]

i also posted a query on this as have been looking at the rinni system as well am thinking of going for the biggest tank and the smallest gas booster but am also wondering how much power it will use to pump the water from the collector on the roof to the storage tank on the ground ? any one have any ideas