Water Heating

Joe94

I haven't found a lot of information on the forums about water heating. What is everybody using and how is it set up?

mike95490

Re: Water Heating

I have a Rheem rooftop glycol loop/storage tank unit. Seemed to be working good over the summer, but now in winter, on sunny days I see no heat gain from it. Time to call the warranty man.

AceNZ

Re: Water Heating

I'm using an evacuated tube-based system.

The tubes collect heat, which passes through a heat exchanger at the top; water doesn't flow in the tubes. The vacuum acts as an insulator, so they continue to work in windy or cool weather, as long as some light is present.

A small electric pump is triggered by a controller when the temperature difference between the collector on the roof and the bottom of the hot water tank is more than 8 deg C. The system works well enough that I turned the electric element in the hot water tank off in early November (southern hemisphere!), and haven't had to turn it back on yet. Even with relatively heavy use, the tank regularly reaches the set limit of 80 deg C.

Attachment not found.

techntrek

Re: Water Heating

My goal is a drainback solar thermal system with a dedicated heat exchanger + storage tank. That allows the use of only one circulation pump instead of two which cuts the electric use to about 1/3 that of two pumps. Short payback, little maintanance, no glycol, automatic freeze protection.

westbranch

Re: Water Heating

TnT, what about water hardness. We have 11grains total hardness and it is too high to use in evac. solar heaters, will eventually plug the system tubing channels.

Sulfur

Re: Water Heating

If you live in a cold climate and gas water heat is not available or desirable, or if existing house design is a constraint for solar water heater then consider adding more PV and use a standard electric water heater. I have no gas on property and heat water with standard 50 gallon electric hot water heater. PV is simpler but the solar water heat is probably more fun.

solar_dave

Re: Water Heating

I have a 4X10 regular box panel made locally. I doesn't run any antifreeze but I don't have a real freeze risk. It is under line pressure full time. It has a small pump and a Goldline controller with a 80 gallon electric tank not hooked up to electric as a pre heat system for my high efficiency nat gas Kenmore hot water heater. I supplies 100% of our hot water for about 10-11 months and does a reasonable preheat all year. BTW the Goldline controller will pump some water to the panel on particularly cold mornings from the storage tank to ensure no freeze situation.

From November 11 to December 11 we consumed 7 therms of nat gas, both water heating and cooking. So a couple therms higher than our normal 4-5 therms.

Our situation is of course not the norm for most of the USA & Canada.

DanS26

Re: Water Heating

I use the Nyle system. I call it the "too good to be true" project. I use excess solar power from my grid tied system to power this device. It heats my water, cools and dehumidifies my air. It's rated as a one ton AC. I run it in the spring, summer and fall, but not in winter. Qualifies for 30% tax credit from the IRS and another 30% from local utility.

I have it on a timer so I only run it during daylight hours. It works great.Attachment not found.

mtdoc

Re: Water Heating

I also use a Nyle Geyser - same as Joe94. Double thumbs up! Very efficient. 8)

(I don't think there's a 30% IRS credit though -is there? - it doesn't really qualify as a solar water heater even if powered by PV - does it )

techntrek

Re: Water Heating

westbranch wrote: »

TnT, what about water hardness. We have 11grains total hardness and it is too high to use in evac. solar heaters, will eventually plug the system tubing channels.

Both types of drainback systems still run distilled through the panels, heat exchanger, and reservoir. No worries with scale.

DanS26

Re: Water Heating

mtdoc wrote: »

I also use a Nyle Geyser - same as Joe94. Double thumbs up! Very efficient. 8)

(I don't think there's a 30% IRS credit though -is there? - it doesn't really qualify as a solar water heater even if powered by PV - does it )

Nyle does qualify for the tax credit. Form 5695 Line 24a Energy efficient building property. Limit of $300 tax credit. Which is about 30% of the cost of the Nyle.

Line A. Energy-efficient building property is any of the following:
* An electric heat pump water heater that yields an energy factor of at least 2.0 in the standard Department of Energy test procedures.

* An electric heat pump that achieves the highest efficiency tier established by the Consortium of Energy Efficiency (CEE) as in effect on January 1, 2009.

* A central air conditioner that achieves the highest efficiency tier that has been established by the Consortium of Energy Efficiency (CEE) and is in effect on January 1, 2009.

* A natural gas, propane, or oil water heater that has an energy factor of at least 0.82 or a thermal efficiency of at least 90%.

* A stove that uses the burning of biomass fuel to heat your home or heat water for your home that has a thermal efficiency rating of at least 75% as measured by using a lower heating value.

mtdoc

Re: Water Heating

DanS26 wrote: »

Nyle does qualify for the tax credit. Form 5695 Line 24a Energy efficient building property. Limit of $300 tax credit. Which is about 30% of the cost of the Nyle.

.

Oh crap. I bought mine in 2011 I think. Is it too late to claim the credit?:roll:

DanS26

Re: Water Heating

mtdoc wrote: »

Oh crap. I bought mine in 2011 I think. Is it too late to claim the credit?:roll:

File an amended return. Get your $300 back. Three year time limit to file an amended return.

Note it's line 6a for tax year 2011.

Lee Dodge

Re: Water Heating

Small solar hot water preheater with one Viessmann 200F 27 ft^2 absorber area mounted at 36.9° tilt angle (9:12 pitch roof) from horizontal compared to latitude of 38.6°, Heat Flo HP 50-gallon stainless steel solar storage tank, followed by natural-gas fired tankless water heater with variable input firing range from 11,000 to 199,000 Btu/h. It is not well instrumented, so I don't know the details on energy collected and used. Seems to provide almost all the hot water during about 8 months out of the year and always provides some preheat the remaining months for one person. Natural gas usage during the summer for hot water and cooking is about 1 or 2 CCF (~therms) at $0.72/CCF, so the solar hot water is doing most of the work during that time. Natural gas usage shown at http://www.residentialenergylaboratory.com/rel_energy_use_natural_gas.html

Sulfur

Re: Water Heating

These Nyle water heaters are an air source heat pump. Do you have them located in a space that it temperature controlled by your HVAC? If not, how cold does its room get in the winter time? In summer time these will aid the HVAC but in winter time they will counter act the HVAC that is heating the house. They seem like an excellent choice for warmer climates where natural gas is not available or desired.

DanS26

Re: Water Heating

Sulfur wrote: »

These Nyle water heaters are an air source heat pump. Do you have them located in a space that it temperature controlled by your HVAC? If not, how cold does its room get in the winter time? In summer time these will aid the HVAC but in winter time they will counter act the HVAC that is heating the house. They seem like an excellent choice for warmer climates where natural gas is not available or desired.

As I mentioned in my original post, I do not run the Nyle in the winter. I have it connected to my cold air duct system with a baffle so that in the spring and fall the cool air is vented to the non-living space basement. In the summer the baffle directs to the living space. Works great. Dehumidifies my basement.

Since I have excess solar PV power I only run the Nyle system during the daytime. I use an Intermatic 7 day timer to make the switch four times a day since I also do not run the water heater when I'm sleeping. My operating schedule is like this:
10pm to 5am

---

everything off
5am to 8am

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propane powered
8am to 4pm

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solar powered
4pm to 10pm

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propane powered


I'll post a pic later to show the baffle system.

Sulfur

Re: Water Heating

It looks like a great way to heat water during the months your not heating your house. Do you have a net metering meter? I am curious why you only run it during the daytime?

DanS26

Re: Water Heating

Sulfur wrote: »

It looks like a great way to heat water during the months your not heating your house. Do you have a net metering meter? I am curious why you only run it during the daytime?

Here in Indiana most non-public owned electric utilities use a system called "net billing". In a net billing arrangement the utility buys excess solar produced power at wholesale rates and then at night sell it back at retail. Yes that sucks, but I take the positive approach and consider the wholesale/retail rate difference as the price I have to pay to use the grid as my storage device (ie same as a battery), thus I do not have to invest in an expensive battery, controller system. I can also look my neighbors in the face and tell them they are not subsidizing my solar system which is the case in the "net meter" systems in most other states.

So in this net billing system it is to my advantage to use as much of my internally produced power as possible, because it is offsetting power that I would have to pay retail rates. So I am constantly looking for ways to use my excess solar power because the benefit is calculated at retail rather than wholesale rates which is about $.02 per kWh. The Nyle with a timer was a perfect fit. Next up will be an EV also on a daylight timer.

Attached is a couple of pics of the Nyle that I promised. One is the duct and baffle system I use to connect to the cold air duct work in the house. Note the lever in the pic. The other pic is of the insulated connections to the water heater. The way it works is that you remove the drain faucet and insert special piping into the tank. A temperature inversion process takes place in which hot water rises in the center of the tank and cold water flows down on the perimeter and is sucked into the Nyle to be heated. I used PEX plumbing to make the connections.

AceNZ

Re: Water Heating

westbranch wrote: »

TnT, what about water hardness. We have 11grains total hardness and it is too high to use in evac. solar heaters, will eventually plug the system tubing channels.

I'm not sure which vacuum tube solar hot water systems you've been looking at, but the one I'm using doesn't have fine capillaries that can be blocked by water scale from hard water. They also don't use glycol, nor do they need frost protection.

http://www.solarpeak.com/

westbranch

Re: Water Heating

As to plugging the pipes, our new place is at 11 grains hardness, my present place is at 65 grains, so high that whenever we have it tested the tech gives me an 'Oh ya' look, and then his jaw drops as he has to keep titrating.... I am just a bit cautious, but the manufacturer of our setup advised me NOT to use the water unsoftened, due to buildup over time, but they were talking about a non drain back setup.

CDN_VT

Re: Water Heating

AceNZ wrote: »

I'm using an evacuated tube-based system.

The tubes collect heat, which passes through a heat exchanger at the top; water doesn't flow in the tubes. The vacuum acts as an insulator, so they continue to work in windy or cool weather, as long as some light is present

I am running the same , But in Nov mine is done , (Northern hemi) . Mine has solar panels to run & turn on the pump . No sun , no need . We had enough hot water till the wood stove takes over.. on the shoulder season , quick showers are requested .. I built mine , run rooftop glycol loop/exchanger to tank unit system that parallels the fire box / supply on demand or standard electric ..For the last few years , 99% fire or solar ..

VT

techntrek

Re: Water Heating

As I mentioned earlier, it is a non-issue for a drainback system. Only distilled water flows through the heat exchanger and panels.