solar-thermal panels

[weesa20]

Looking at solar-thermal panels for the house- to supply the hot water- wondering if anyone has added them before and if anyone has advice/things to look out for...its feasible and fairly reasonable (after tax breaks)...so I am looking hard at it.

 

[Donman]

Weesa20, I am considering doing the same thing, only not spending much money on it. I already have a hot air solar panel (4x8 horizontal) that I salvaged from a re roof job. I am thinking of using the blower to force the hot air down the 4 inch chimney of a gas water heater, keeping the spiral diffuser in place, and piping the intake air of the collector from the bottom of the water heater. This collector produces 130 degree air with a cold intake and i'm thinking that using this in a closed system that cycles the air over and over that it could get much hotter. Even if it does not, 130 degree water is hot enough anyway. The beauty of doing it this way is that the water heater could be in series with and before my electric water heater to either preheat the water or totally heat the water so the elements don't come on at all. It will not need any pumps or controls besides the existing blower switch in the collector which switches the blower on when there is heat to blow. I am thinking that even though the flue temperature is only 130+ degrees instead of a much higher temp when burning gas, that given enough time (4 to 6 hrs or more of sunlight) the water will get to the same temp as the air.
Donman

 

[JonnyL]

if you do thid don you better get co detectors and have the fire dpt on speed dial

 

[BobRip]

Looking at solar-thermal panels for the house- to supply the hot water- wondering if anyone has added them before and if anyone has advice/things to look out for...its feasible and fairly reasonable (after tax breaks)...so I am looking hard at it.

I have the Velux ones. What I thought made them stand out was that they look just like skylites. As a matter of fact Velux is a skylite manufacturer. My brother in law who appraises houses told me that the ones that sit off of the roof reduce the value of a house and make it hard to sell. I seem to get heat even on a cloudy day. I get more on a sunny day though.

 

[Donman]

if you do thid don you better get co detectors and have the fire dpt on speed dial

I guess I did not make myself clear about the gas water heater. It will NOT be hooked up to gas - wont even have a burner in it - just hot air.
Donman

 

[magicheater]

Weesa20, I am considering doing the same thing, only not spending much money on it. I already have a hot air solar panel (4x8 horizontal) that I salvaged from a re roof job. I am thinking of using the blower to force the hot air down the 4 inch chimney of a gas water heater, keeping the spiral diffuser in place, and piping the intake air of the collector from the bottom of the water heater. This collector produces 130 degree air with a cold intake and i'm thinking that using this in a closed system that cycles the air over and over that it could get much hotter. Even if it does not, 130 degree water is hot enough anyway. The beauty of doing it this way is that the water heater could be in series with and before my electric water heater to either preheat the water or totally heat the water so the elements don't come on at all. It will not need any pumps or controls besides the existing blower switch in the collector which switches the blower on when there is heat to blow. I am thinking that even though the flue temperature is only 130+ degrees instead of a much higher temp when burning gas, that given enough time (4 to 6 hrs or more of sunlight) the water will get to the same temp as the air.
Donman

I love to experiment too but I do not think that will work as you describe. Air is a horrible medium of transfer. No way you can get the water to 130 degrees with 130 degree air, system will stall before that. Let me know if it works for you. I have hot air panels too along with fluid panels in separate systems. Even with fluid panels you can never raise the water temp equal to the input temp of the fluid. The closer the two get to each other in temp the slower the heat transfer. I have been able to achieve a 20 degree difference at best. Same results with a boiler in the winter.

 

[quicksandfarmer]

I've found this site to be a wealth of solar information: BuildItSolar: Solar energy projects for Do It Yourselfers to save money and reduce pollution

 

[weesa20]

Bob- good thoughts- I just recently had the house appraised for a re-fi and the appraiser was pretty tough so I was going to call her to see about a realistic value of adding panels- the panel guy says that it will add 20$ of value for every dollar saved in hot water heating costs in a year- so we have estimated we would save (conservatively) 300$ in hot water heating energy per year(2 electric HW heaters-a 43 and a 50 gal)- so using his formula (I don't know where he gets it from, but...) it would add about 6k$ to the value of the house. He didn't say anything about reducing value. The panels would be going on a back section of roof that changes from 7:12 to 4:12 pitch, and the house is a pretty tall 2 story so you might not even see them if you didn't know to look or maybe just see the edge of them any way.
Here are the ones they are suggesting:
Premium LA - Solar Thermal Collectors - Solar Thermal Systems - Solar Energy Products-Schüco

The way they are talking about setitng it up is to use their 80 gal tank (which comes with a 2k$ cash back incentive) in series with my 50 gal tank which is only 6 months old and discarding the 43 gal tank- so I would go from 93 to 130 gal of available hotwater- should be plenty for my family (max of 4) and hopefully the electric elements won't have to kick on at all.

 

[BobRip]

The way they are talking about setitng it up is to use their 80 gal tank (which comes with a 2k$ cash back incentive) in series with my 50 gal tank which is only 6 months old and discarding the 43 gal tank- so I would go from 93 to 130 gal of available hotwater- should be plenty for my family (max of 4) and hopefully the electric elements won't have to kick on at all.

I have my solar tank (80 gallons) in series with my electric one (50 gallons). If it's sunny, the electric does not cut on. If it's cloudy we still get a fair amount of heating. It can go to over 100 on a moderately cloudy day. This is very variable of course. If there is snow on the collectors, I get nothing.

I have a lot (I mean a lot) of trees around the house. I have topped a few, but the wife does not really like it. I have to aim the collectors WSW (about 250 degrees). I had a third collector installed to compensate for this. I am still waiting for the Virginia rebate. They ran out, but now have more money.

 

[magicheater]

Today was sunny, I have 6 panels on the roof, domestic hot water got to 100 degrees today. I have 3 tanks in series totaling 120 gallons in series before the gas water heater. In the winter I can raise the 120 gallons to 135 degrees from ground temp of 40-50 degrees in 2-4 hours with the boiler, depending on heat load. I run my boiler at 160-170 degrees at the most.