Topic: Integrative Solar Hot Water Heater

Integrative Solar Hot Water Heater 

Why the integrative system:

- Completely passive, no pumps, electrical heating coils or elements

- Less expensive than split systems (in some cases less than 1/2 the cost)

- Efficient even on cloudy days

- Easy installation and operation; cold water in, hot water out

- Works with either non-pressurized or pressurized water source and can be tied into municipal water supply

- Rebates; tax rebates from state and federal government can cover over 1/2 the cost in some cases

- Green, truly a green system that can provide the hot water needs for commercial or residential purposes

- Pays for itself, even without rebates in less than five years

- Lifetime expectation of 20+ years
____________________
reynantevargas
http://www.greencajun.com/

Re: Integrative Solar Hot Water Heater 

- Completely passive, no pumps, electrical heating coils or elements

Well in that case it wouldnt pass NZ plumbing regulations, unless it was used as a pre heating device only.

Re: Integrative Solar Hot Water Heater 

Unless you have a lot of money for solar hot water in New Zealand you are quite right the integrative solar unit is by far and away the best unit. Not all integrative solar units are suited to mains presure. The unit you pictured is a good one it has in internal copper coil to extract the solar heat thus suited for mains pressure but many units for sale in NZ are simple units with no internal coil and only suited for low pressure. It is not well understood integrated units are ideally suited for mounting on the ground with no requirement for a council permit which makes for a very simple and low cost installation in the range of $1500-$3000. You are quite right in saying the payback period is low.

Have a look at http://cobournereserve.atnz.net
Scroll down to solar hot water article.

Re: Integrative Solar Hot Water Heater 

Hi Remp

One of my key concerns is that a child run into one of these systems on the ground and gets very hurt.

Seeker

Re: Integrative Solar Hot Water Heater 

>> no requirement for a council permit

Untrue, any such device connected to the potable water supply requires a permit in NZ. Because you cannot guarantee the water will be heated to 60c each day with this unit, it cannot legally be used as a stand alone hot water heater in NZ; except when used as a pre-heater to an existing HWC system.

Mike

Re: Integrative Solar Hot Water Heater 

Just turn on the power to an electric element and be done with it mate. Why does everyone on this forum have to pull things apart and dis someones product or ideas!
Michael

Re: Integrative Solar Hot Water Heater 

There is no requirement to heat water to 60 each day, and a stand alone solar set up like this wouldn't need a permit either - if it is connected to the potable water supply some of the installation is supposed to be done by a plumber.

Re: Integrative Solar Hot Water Heater 

Hi Remp
One of my key concerns is that a child run into one of these systems on the ground and gets very hurt.
Seeker

Hi Seeker

One thing is the tubes run cold. I have two systems One has dry tubes the other has wet tubes. Both run cold. The only thing hot is the main hot water cylinder can get quite hot to the touch on a hot day. It is the sun on the metal cover. But the cylinder is quite high. It would be difficult for a child to touch the cylinder.
The main potential problem is risk of falling onto the tubes causing a tube to break and the child scalded with boiling hot water. The dry tubes have no water in them. The wet tubes do. And The sharp edges of the glass tubes. They are toughened glass. Able to withstand 25mm hailstones.
But any sort of accident would be unthinkable. The solar unit could be in a locked area or fenced with a strong net.
Remp

Re: Integrative Solar Hot Water Heater 

>> There is no requirement to heat water to 60 each day

This requirement exists with a number of options
Quote from the NZ Regs G12

3.5 Protection from Legionella bacteria
3.5.1 To prevent the growth of Legionella
bacteria, solar water heaters must either:
a) have a continuously energised heating
element fitted within 55% of the bottom
of the water tank (by volume) and a
thermostat set to 60°C or higher, or
b) be controlled so that the water above the
element is heated to 60°C once a day, and
the element is in the bottom 20% of the
water tank (by volume) and no more than
150 mm from the bottom of the tank, or
c) be controlled so that all of the stored water
is heated to 60°C or higher, once a week
for not less than 1 hour. The temperature
must be measured by a probe in the bottom
20% of the water tank (by volume) and no
more than 150 mm from the bottom of the
water tank. For open loop systems the stored
water includes the water in the solar collector
and water must be circulated through the
collector during the heating period.

Re: Integrative Solar Hot Water Heater 

>> no requirement for a council permit

untrue, any such device connected to the potable water supply requires a permit in NZ.

I do not say things that are untrue.

Are you one of these people who spout requlations and have nothing original to contribute.

I am looking for ways to make solar hot water more affordable in New Zealand because as time goes by electricity will become more expensive and solar is something relatively easy that people can do as a DIY activity. I believe putting the unit on the ground is a major step forward in this regard.

(a) If the solar unit is used as a preheater it can be at any temperature depending on the sunshine.
(b) There are no permit requirements for a preheater device.
(c) You can do all the work yourself fit the solar unit in place safety fence running the pipes etc but the final connections and any safety items should be done by a registered plumber who signs off the job.

Remp

Re: Integrative Solar Hot Water Heater 

Remp,
You are correct, your device does not need a council permit. Connecting items to the potable water supply do not always need a permit, but as you say the last connections should be done by a plumber.

The 60 degree water business. Whilst it is true that anyone paid to install a water heater has to ensure it can meet the regulations - the houseowner can do whatever he chooses - because there are no sanctions ie a houseowner cannot be prosecuted for 50 degree water.

In reality 50 degree water is much safer than 60 degree - it would appear that contracting legionnaires from a domestic hot water system has never been recorded - scalding on the other hand is quite common, and has the potential to kill.

My thermostat will remain set at 50 (the maximum allowable in the US), until I hear of anyone contraction legionnaires from their shower.

Re: Integrative Solar Hot Water Heater 

As all solar systems use copper pipes, the cu ions dissolved in the water act as a natural fungicide so is extremely unlikely that such systems will harbor legionnaire no matter what temp of the water.
By regulation an anti scald mixer valve must be fitted to any solar system in NZ as it is considered an uncontrolled heat source. The valve is usually set for 55 c at the taps, but incase of younger children then there is no one to stop you from lowering it to 50 c; I believe the regs say 45 c as the max water temp in places like child care centers.

Remp your system would work fine ground mounted, or even raised slightly on wooden posts, makes access easy to clean off the dust dirt etc. Mounting such systems on roofs due to the weight of all that water often means the roof requires strengthening and unnecessary inspections by council or requires engineers report. If it was me I would use it as a pre-heater feeding a small 90L cylinder with electric element. Most of the time the element would remain off, except in the winter months.

What is the thickness of the insulation surrounding the tank, as its outdoors ideally should be > 60mm polyurethane to avoid excessive heat loss during cold nights.

Mike

Re: Integrative Solar Hot Water Heater 

Thanks Mike I think you are right.


My plan is to investigate if I can get hot water from the sun and turn that into electricity.
I hate paying high prices for electricity and I am thinking about peak oil. At present PV panels are expensive. Deep discharge batteries are expensive. They say panels will come down in price. I believe oil companies will buy up all the solar manufacturers and it will still be expensive. I have to do this with minimum expenditure.

I have succeeded in stage one to purchase a solar unit with a self contained hot water cylinder and 20 glass collector tubes. It is sitting on a concrete sun-deck. The cylinder and tubes are 300 liters of water. At present the solar is not connected to my household water because I am studying the unit.

I have found
(a) It will boil water.
(b) I can easily control the unit heating by placing a shade cloth on the tubes.
(c) If there are two sunny days in a row the unit needs controlled or it will overheat however summer this year has often been patchy with rain or overcast (Auckland area).
(d) On an overcast day there is very little water heating. Maybe a few degrees
(e) If it is overcast and raining there is no heating but the glass tubes get cleaned.
(f) Even though the unit is not connected to our household water we still use the hot water for the dishes. Sometimes in the washing machine. For my wife's paddling pool and for killing weeds in the path and driveway.
(g) Electricity prices have gone up but our power account has not gone up. I guess that means we are actually saving a small amount even though the solar unit is not connected to the household water.

The hot water cylinder is 240 liters with an additional 60 liters in the glass tubes. I believe this is too much water for 20 tubes. When the cloud cover moves away I want the solar unit to rapidly start heating but it is sluggish. By emptying half the water it heats a lot faster. I can see the thermometer moving quicker. When the unit is connected up as a pre-heater you cannot run it half empty so will be back to slow. That means it is not much use for the Winter however I am planning to double the number of tubes.

Bad points.
Galvanised steel stand rusts quickly in places. Needs rust converter. The stand is well made and strong.
Stainless steel bolts rust. Replace the bolts
The tubes are full of water. Cannot be replaced without empty unit
Dangerous if a child falls onto the wet tubes and breaks a tube.
As far as I can see there is no recorded accident of this nature on the internet
These units on the ground should be fenced
Water capacity of cylinder too large for the number of tubes
Just adequate cylinder insulation 50mm. Looses 10 degrees C overnight warm summer night.

Good points
Cheap $1000 bought locally from trade me NZ
Similar units were $209 US dollars in China plus shipping plus landing costs.
When I enquired 1 year ago they would sell to anybody one off quantity.
Now you have to order a minimum quantity about 20 units.
Heats water like it should
Looks neat
All my friends and family are very impressed.
Tubes are cold
I love my solar.

With 300 litre water size this solar unit is struggling to heat up that much water in the variable Auckland climate. It is about 2 meter sunshine capture area. With continuous sunshine it would be very suitable but for sun/cloud/rain weather it is not heating enough. The unit takes two days to heat all the water from cold up to 70 degrees C. Thats with not much hot water being drawn off. We are a two person household. The house hot water cylinder is 135 litre grade A. We have night heating from 11pm to 7am. We never run out of hot water. The solar unit would be useful as a pre-heater which is why I bought it. I may even be able to reduce the cylinder size from 300 litres down to 150 litres.

When peak oil comes I believe electricity will be the main energy source. It will be rationed and expensive. It may be possible to produce electric

Re: Integrative Solar Hot Water Heater 

I should mention my solar unit is probably near the bottom as far as performance goes.

Stage two.
I am up to stage two.
(1) Hot water takes a lot of heating therefore it seems hot water is storing a lot of energy.
(2) It is possible hot water from a solar unit can be turned into electricity
(3) I have looked at hundreds of possibilties and discussion groups
(4) Peltier cells are possible. Metal hydride heat engine. Stirling engine. MIT has a heat to sound to electricity technology
(5) Storing hot water may be a better proposition than expensive deep discharge batteries. It is hard to tell exactly the state of charge of a battery except by moderately expensive test equipment. The problems with batteries multiply the more batteries a system has. Batteries are a recurring cost. You just get the system running well and a battery needs replaced.
(6) It seems possible to have one large or several smaller hot water storage cylinders very well insulated. This is your heat battery. Unlike a regular battery there is no deterioration of the hardware (hot water container) so should last a long time. Unlike a regular battery there are no discharge problems. Unlike a regular battery your heat store will not fail. It might get cold too quickly but you can fix that. It might leak but you can fix that. You can tell at a glance the heat capacity you have remaining by looking at a simple hot water thermometer. You can try very hard to have hot water in hand for a rainy day.
(7) For a normal solar preheater situation the plumber would fit a tempering valve to limit the output water temperature to 60 degrees celcius or thereabouts. The tempering valve mixes cold water with your solar hot water. But if you are using your solar unit to make electricity you can have the solar water as hot as it will go without boiling. One would think more water temperature = more stored energy.

remp

Re: Integrative Solar Hot Water Heater 

At least your thinking about these things which is more than a lot of people -

The efficiency of a solar set up is irrelevant, all that matters is the cost versus the amount of energy captured, a low cost low efficiency set up is far better than high cost and high efficiency.

Storing electricity is a major problem, one of the best ways is to use the grid.
Unfortunately heat is the lowest from of energy, trying to turn it back into electricity isn't a practical proposition.

Re: Integrative Solar Hot Water Heater 

Heat storage through phase-change materials is perhaps a better technology than heat storage through warm water. "Abengoa" uses heat storage in liquid "salt" tanks.

Re: Integrative Solar Hot Water Heater 

Hello Remp

I disagree with your contention that integrative solar hot water heaters are "by far and away the best unit":

1. A pumped evacuated tube system is MUCH more efficient (captures more of the available solar energy) than a passive thermo siphon system.

2. Sure the installation cost is higher, but I have seen your link of the work-arounds you intend to do: shade cloths, fencing, pumping out the tank to change anything, water leaking when a tube breaks (and believe me they do), halving water cylinder volume etc etc. This is not a trouble-free or plug and play solution for the average household.

3. With a properly designed and installed system, which has some level of professional solar hot water expertise, you have the outcome of a safe, properly operating system from a reputable supplier, with product warranties, maintenance servicing, and most importantly, no accidentally broken tubes and damaged grandchildren.

Your system may or may not win on cost (and all your hard work looks like you have spent a fair bit of time on your system), but operationally it is far inferior, for normal household applications, to a high performing professionally packaged system.

As for ANON 3:44pm: a low cost low energy efficiency setup is not far better than a high cost high energy efficiency setup. I think there is a place for each setup, depending on your personal tradeoffs and personal circumstance.

Trade and SHW user

Re: Integrative Solar Hot Water Heater 

>> 1. A pumped evacuated tube system is MUCH more efficient (captures more of the available solar energy) than a passive thermo siphon system.

This is not necessary always true, It is true when the collector is mounted some distance from the storage tank; but in this situation where the evac tubes are water filled and directly connected to the tank then a pumped system would offer no advantage in efficiency.
In fact it has disadvantages in this situation with extra complexity and bits to go wrong. Pumps fail, sensors fail, controller fails if its mains powered and there is a power cut.

In reality both systems work well and save considerable money. My hot water cylinder hasnt had its electric element turned on for more than 3 hours since beginning of sept last year, proving how effective a well designed DIY solar setup can be.

Mike

Re: Integrative Solar Hot Water Heater 

doesnt make sence to me since pumped water always has a better heat transfer over stagnant or natural thermosyphen

Re: Integrative Solar Hot Water Heater 

i have used a passive system for years and find it very simple and reliable. i have never had a problem with it and it has payed for itself many times over. i only need to turn on my gas hot water if the weather is crap for 4 days, but even then it is a great pollisher (preheater) for my gas califont.
i would never install a pumped system because to me it defeats the purpose of having solar water heating. just in case anyone was interested.

Re: Integrative Solar Hot Water Heater 

Hi Anon

I, for one, am very interested!

Just a few questions:
- Are you off-grid?
- And what is the arrangement you have: tank on roof or tank not on roof (inside roof space or something)?
- What is the size of your storage tank and area of the collectors?

As to your post:
I think that a lot of people go for solar because they want to capture all that heat landing on their houses. Adding a pump does not defeat this purpose: the pumps draw very little power for the amount of additional heat they allow the collectors to capture as opposed to thermal siphon.

Perhaps for off-grid applications you might want purely thermo-siphon, but even in this application, a pumped system may still get more watt hours of heat capture than the watt hours chewed up by the pump power supply.

The issue I have with some thermal siphon systems where the tank is on the roof is the amount of heat you lose overnight. Best to have showers at night in that case, so you won't care if the water gets cold and stays cold all night, all ready for the next day's sun capture!

I have seen an older flat panel "tank on roof" system that loses ALL of its heat overnight, and then the electric element kicks in and heats the entire tank of water - which the householders use for their showers in the morning! Their solar hot water system is basically only heating water for the evening dishes. The irony of this system is that because of the daily heat loss, it uses more electricity than a normal all-electric cylinder sitting in a cupboard. But the cost of replacement, the location of the bathrooms, the cheap night rate electricity, all combine to make it totally uneconomic to change (or even touch) the system.

Seeker

Re: Integrative Solar Hot Water Heater 

my unit has the tank connected straight to the evacuated tubes. the insulation is very good and water is piping hot in the morning without an electric back up.
the only problem i have with it is the fact that its a low pressure system.
i want a mains pressure system to replace it with, but im having trouble finding one suitable.
the whole pumped collector idea is of little use to me as i have no hot water cylinder. just the gas califont and whatever i put before it.
as soon as i can find a mains pressure evacuated tube system with a tank on the roof i will buy it. i have had a good experience with my thermosiphon tank on roof model.

Re: Integrative Solar Hot Water Heater 

Hi previous poster: have you checked out the original post for this thread? It looks like a high pressure tank on rood system with evac tubes......

Re: Integrative Solar Hot Water Heater 

Hi previous poster: have you checked out the original post for this thread? It looks like a high pressure tank on roof system with evac tubes......

Re: Integrative Solar Hot Water Heater 

Integrated water heating systems combine the heating requirement with the hot water needs, saving money on total system installation.
A single boiler is used, requiring only one combustion burner and one vent. Often these systems employ an insulated external storage tank with a high-efficiency low-mass boiler to heat the water, which then passes through a fan coil.
The system then blows the heat around the house in a warm air distribution system, like a conventional furnace.

For integrated systems that do not use high efficiency boilers, the initial cost saving is soon eliminated by very low seasonal efficiency.

The heater is sized to produce enough heat to warm a house on the coldest winter day. However, in the spring, summer and fall, when no heating is required, the same heater heats domestic hot water only.

The effect is an oversized water heater that operates for several months of the year with a low heating demand – and low efficiency, as a result.

Integrated system that has been around for many years, particularly in the Maritime provinces, is a fuel-fired hot water boiler with a tankless coil water heater that uses a heat exchanger in the boiler to heat tap water but without a separate storage tank.

The water flows through a coil inside the boiler whenever a hot water faucet is turned on. The drawback is that this system is dramatically less efficient in warmer months, when space heating is not required, as the boiler water must be kept hot all the time.