Thoughts on solar hot water heaters

[fronty]

I have a solar hot water heater system installed in my house. It works in conjunction with an electric water heater. Well, I'm planning on replacing the roof this week, and I am debating on whether to just toss the solar system. I will have to remove the panels anyways to lay down the new roof. I just don't know if it is worth reinstalling the panels. The system is 26 years old and the circulator pump seems to run constantly. The pump pulls less than 1 amp at 115volts. What is the typical life expectancy of a solar hot water system. Are they even cost effective anymore?

[plumberscrack]

The pump should run almost continuous during the day depending on the control package.
26 year old system might have another 10 years or more left in it.
What's the condition of the brackets and panels? Are they cloudy?
Either way you will have to drain the glycol from the system and store it for reuse or dispose of it legally. That can be expensive.

[fronty]

The pump should run almost continuous during the day depending on the control package.
26 year old system might have another 10 years or more left in it.
What's the condition of the brackets and panels? Are they cloudy?
Either way you will have to drain the glycol from the system and store it for reuse or dispose of it legally. That can be expensive.

Yes, the panels are cloudy. I felt the recirculating tubes and they are not warm/hot. I'm not sure if this system is still working.

[plumberscrack]

Yes, the panels are cloudy. I felt the recirculating tubes and they are not warm/hot. I'm not sure if this system is still working.

Cloudy panels? that makes your decision alot easier doesn't it?

Too bad really I've done a bit of solar work and hate to see someone walk away from it.:(

[wbrooks]

Can you buff up the panels with an automotive type paint restorer (fine polishing grit in solution)? I did this to my clouded and sand blasted headlights and they came out like new.

[Woussko]

I think Wayne is refering to Rubbing Compound which you can buy at auto parts stores and sometimes I've seen it at Walmart. It's great for removing scratches as long as you're willing to do some work rubbing away with a rag. When done, wash it off and rinse. Then have a look.

By the way it also comes as paste in small cans like auto wax does.

[Bob D.]

Since you have been using this system for so long you may have lost track of how much (if at all recently) money or energy the solar system saves you.

Before you give up on it altogether, why not do some simple research. Shut the system down for a month and see what you electric bill is. Then compare it to last months and also the same month in past years (however far back your records go). Is it higher or lower? From this simple comparison is the system saving you enough money to justify repair/replacement of the panels?

Are you losing money (burning kilowatts on the circular and not getting anything worthwhile in return)? Maybe its time for a completely new system or do away with it entirely if the cost to bring its performance back it prohibitive to you.

[PLUMBER RICK]

truthfully, the savings for a residential hot water solar system are not there.

back in the 70's when they had all the tax credits, it paid. today the cost for a replacement tank is more than any savings a residential customer will receive.

now solar for a pool still pays. quick payback and cheep to install and maintain.

solar electric. still a good tax incentive and a relative short payback period.

solar domestic water heating. a big joke:eek: no tax incentives and you'll never recoupe your investment.

rick.

[fronty]

I appreciate the help guys. I haven't even looked into this system yet. I guess I was wrong in the way I was thinking this thing worked. I thought that the water from the expansion tank just circulated up through the panels. I didn't know that glycol was involved and a heat exchange process. Well, I'll snap a few pics tomorrow. My hot water heater is in the attic and the solar water tank is HUGE. If I remove the solar system, I'm just going to install a new water heater in its place and eliminate the water heater in the attic (repipe everything). Well, it has been pretty hot these days. Couldn't I just take a temp reading at the ingoing and outgoing pipes. I don't really know how to even diagnose it to see if it is still functional at this point. Can someone give me a quick run through of how it is supposed to operate?

[PLUMBER RICK]

i doubt that your system uses glycol. this is a domestic hot system right:confused:

i wouldn't spend the money on reinstalling it on a new roof. i doubt that the utility charge at the end of the month will change much.

rick.

[ToUtahNow]

i doubt that your system uses glycol. this is a domestic hot system right:confused:

i wouldn't spend the money on reinstalling it on a new roof. i doubt that the utility charge at the end of the month will change much.

rick.

fronty does not say where he lives but it would not be unusual to have a shell and tube exchanger using Propylene Glycol Antifreeze as a transfer liquid for a domsetic water solar heating.

Mark

[Bob D.]

I agree with Mark if the location is anywhere where the temperature could approach freezing that a glycol system would be needed with a heat exchanger in that case.

Rick, you said you don't think the electric bill would show much difference w/o the solar heater in service. If that is the case then I would not bother with it. Too much maintenance and extra equipment to maintain for no return. Here in NJ I don't think a solar HW heater would pay back fast enough.

I don't think you'll gain enough information measuring the input and output temperatures over a short period to know if the system is working or has some level of efficiency at which you could say it is profitable to continue to operate it.


I'd like to put in a PV system and help cut my dependance on the grid for all my power. I don't know if we will be in this house long enough to make it worthwhile though, so maybe the next home. I am just beginning to investigate systems and have a plenty of questions.

One of the four utilities that operates in NJ has said they will provide up to 100 million dollars (http://www.pseg.com/media_center/pressreleases/articles/2007/2007-04-19.jsp) in loans to residential and business customers for solar systems.

[fronty]

Sorry, I live in central Florida. This is a residential installation. I'll post pics tomorrow of the system.

[Crappy days]

I'm with Rick get rid of it.

[plumberscrack]

i doubt that your system uses glycol. this is a domestic hot system right:confused:
rick.

Frankly I'd be surprised if it didn't use Glycol. Most solar systems do and it probably wouldn't have lasted 26 years without it.

Without seeing your system but I'm guessing you have a huge insulated storage tank which has a heat exchanger inside of it and a separate electric heater next to it. Glycol fluid is circulated through the heat exchanger up and across the panels on the roof to be heated . The hot Glycol on a sunny day can be over 150 degrees. This heats the water inside the storage tank. Now this process takes a long time so if you are using more hot water than the panels can recover or on a cloudy day the electric water heater kicks in. The beauty is you are only paying for the circ. pump to run. The reason why I asked you about the cloudy panels this reduces the efficiency of the system. Not enough heat transfer to the fluid. So you felt the pipes and neither one was even warm. Even a really poor panel system with produce heat so my guess it something else is wrong. First confirm that the pump is running. Now look on the roof for a oily stain near the panels where the glycol would have leaked out from maybe some storm damage? While you are up there see if the panels have a small bleed valve. Your system may just be low on Glycol. If so you'll have to pump some in there from the attic while someone else bleeds the air out. It would only be low if there was a leak or someone accidently drained some out through a valve. I don't know why your system doesn't have a temperature gauge installed- it should.

Now with all that being said if you can get it working with little or no money then I say reinstall the panels after the new roof goes on.

But if you are a wealthy tree hugging ex hippy eco-maniac looking to reduce his carbon footprint then a new system can be purchased for about 8k.:D

~Bill

[Bob D.]

Impeller in the circ pump may be shot after 20 some years.

[fronty]

OK. It looks like it is a glycol system and all of the glycol leaked out of it. The gauge is only reading 4 psig. I'm thinking it is bone dry and the gauge just needs recalibration. Well, what are your opinions on this thing? I guess I have been wasting money on the small pump running. There are two motors in this thing. One is a small motor at the bottom of the heat exchanger. A magnet is attached to the shaft, so I think it turns an impeller within the heat exchanger through the magnet. I have never heard the other pump run although the light on the control says the pump is running and the small motor is running. Can someone give me a quick explanation of the sequence of operation of this thing.

http://i135.photobucket.com/albums/q125/fronty2/Pic044.jpg

http://i135.photobucket.com/albums/q125/fronty2/Pic045.jpg

http://i135.photobucket.com/albums/q125/fronty2/Pic067.jpg

http://i135.photobucket.com/albums/q125/fronty2/Pic001.jpg

The heat exchanger is right above the small motor pictured.

[Crappy days]

Get rid of it , put your money into a tank-less unit if you want to conserve on energy. In the long run this unit is just going to be a headache. My 2 cents

[Crappy days]

If you decide to switch to a tank-less system get estimates now, so you can decide whether to keep it inside or not. If you put one outside you will want the roofers to take out the flashing for your old gas heater ,if there is one (seeing as I have not read the whole thread).

[plumberscrack]

Fronty, I have some bad news for you.
Your pictures tell me alot about your system and it isn't good.
The pump has been running without Gylcol. Pump is dead for sure. No pressure in system means theres a leak somewhere. Relief valve on rooftop has never been changed may be the culprit of the leak or maybe the corroded boiler drain. Look closely at the pump wire housing; is that black soot from an electrical short? The small back motor below heat exchanger is extremely dirty and was probably never oiled every several months as it should have. I'd doubt if it worked at all. With all of these issues combined with cloudy panels I'd rate this system about a 3 on a scale of 1-10 with 10 being excellent. It could be saved but you need to have an expeirenced solar mechanic evaluate it. $600-$800 just for the things that I know are wrong with it and that's being conservative.

~Bill

[fronty]

Fronty, I have some bad news for you.
Your pictures tell me alot about your system and it isn't good.
The pump has been running without Gylcol. Pump is dead for sure. No pressure in system means theres a leak somewhere. Relief valve on rooftop has never been changed may be the culprit of the leak or maybe the corroded boiler drain. Look closely at the pump wire housing; is that black soot from an electrical short? The small back motor below heat exchanger is extremely dirty and was probably never oiled every several months as it should have. I'd doubt if it worked at all. With all of these issues combined with cloudy panels I'd rate this system about a 3 on a scale of 1-10 with 10 being excellent. It could be saved but you need to have an expeirenced solar mechanic evaluate it. $600-$800 just for the things that I know are wrong with it and that's being conservative.

~Bill


Yes, it looks like an electrical short. I killed power to it. The only motor that I have seen run is the small motor below the exchanger. Do you know what this motor is for? Are you saying $600-$800 if I did the work or if I hired someone to do it. I used to work in the HVAC field, so I would feel comfortable replacing the motors, etc. I guess I would have a ton of questions in regards to the glycol. Where to buy, how to charge the system, etc. Now, I'm kind of pissed that I never had the thing running for a long time. I don't really even know how much it would have saved me. I'm actually kind of intrigued. I wouldn't mind getting it running. I just don't want to lose money getting it running/ not get a pay back from lowered utility bills.

[plumberscrack]

Fronty,

All your solar questions can be answered here : http://www.solarexpert.com/dhw-heat.html


Good news, up to $2,000 tax credit if new solar system installed by 12/31/07:D

[PLUMBER RICK]

sure looks like a domestic system to me. i don't see a heat exchange or glycol?


all i see is an expansion tank.


rick.

[Crappy days]

At 800 bucks you are already a third away from installing a tank-less unit. Plus if your holding tank goes out any time soon which it probably will, you will have spent close to the install price of a new noritz installed(in most cases). Look on line and compare the savings. Not to mention think of the space you will free up by removing the holding tank. Also think in the long term maintenance and up keep.

[fronty]

sure looks like a domestic system to me. i don't see a heat exchange or glycol?


all i see is an expansion tank.


rick.


The heat exchanger is above this motor. It looks like a car radiator/ air conditioning coil (aluminum fins).

[plumberscrack]

The heat exchanger is above this motor. It looks like a car radiator/ air conditioning coil (aluminum fins).


I would like to see a good pic of this external heat exchanger because it should be inside the tank.:confused: I guessing it's an supplemental component used to heat this space with that small dirty blower motor.

[fronty]

I would like to see a good pic of this external heat exchanger because it should be inside the tank.:confused: I guessing it's an supplemental component used to heat this space with that small dirty blower motor.


http://i135.photobucket.com/albums/q125/fronty2/heatexchanger.jpg