Circulators for solar hw
Question:
Hi folks. I have inherited some solar hw panels and am setting them up. Panels are mounted and tank in place, need to run pipe and make the connections next. I have been researching pumps for a while. In my installation I will have 22-23 feet (approx 7m) of static head. This will be a drainback system, circulating pure water. I was hoping to be able to configure a PV-driven pump, but I cannot find details of any proven, affordable installation that will deal with this much head and provide adequate flow. I am probably going to end up using a Taco model 009 pump driven off mains power. I have found details of several makes of low-voltage pumps, including March, Hartnell and the "El Sid", but none of them appear to be up to the task. Multiple pumps in series may be workable in theory, but probably not very affordable given the size of PV panel(s) required , plus current booster(s). Have I missed something? It would be really nice to use PV power for circulating the water, but it doesn’t look practical to do so. I am in NB eastern Canada.
Response:
I hope you get a reasonable answer to this. I am designing the same dilemma and am considering the Taco 009 or 010 I can;t seem to find anybody knowledgable in these pump specs. The published specs say they won’t do it, save the two mentioned ones. Also, does anybody know if the power draw on these pumps goes down upon restrictions or lack of head or restrictions?
– Hide quoted text — Show quoted text -> Hi folks. I have inherited some solar hw panels and am setting them up. > Panels are mounted and tank in place, need to run pipe and make the > connections next. I have been researching pumps for a while. In my > installation I will have 22-23 feet (approx 7m) of static head. This > will be a drainback system, circulating pure water. I was hoping to be > able to configure a PV-driven pump, but I cannot find details of any > proven, affordable installation that will deal with this much head and > provide adequate flow. I am probably going to end up using a Taco > model 009 pump driven off mains power. I have found details of several > makes of low-voltage pumps, including March, Hartnell and the "El Sid", > but none of them appear to be up to the task. Multiple pumps in series > may be workable in theory, but probably not very affordable given the > size of PV panel(s) required , plus current booster(s). Have I missed > something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
Response:
> something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
Handy company, also from eastern Canada… http://www.thermo-dynamics.com/solar_pumps.html — Cats, coffee, chocolate…vices to live by
Response:
- Hide quoted text — Show quoted text – > Hi folks. I have inherited some solar hw panels and am setting them up. > Panels are mounted and tank in place, need to run pipe and make the > connections next. I have been researching pumps for a while. In my > installation I will have 22-23 feet (approx 7m) of static head. This > will be a drainback system, circulating pure water. I was hoping to be > able to configure a PV-driven pump, but I cannot find details of any > proven, affordable installation that will deal with this much head and > provide adequate flow. I am probably going to end up using a Taco > model 009 pump driven off mains power. I have found details of several > makes of low-voltage pumps, including March, Hartnell and the "El Sid", > but none of them appear to be up to the task. Multiple pumps in series > may be workable in theory, but probably not very affordable given the > size of PV panel(s) required , plus current booster(s). Have I missed > something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
Hi, These guys appear to offer a high head PV powered pump: http://www.thermo-dynamics.com/solar_pumps.html You might also look at the Dankoff site here: http://www.conergy.us/Desktopdefault.aspx/tabid-157/224_read-1768/ They appear to have some PV driven pumps with high head capability, although they don’t list DHW as an application they might work? Dankoff appears to have changed hands? I remember reading a HomePower article that stated that drainback systems (which have higher head requirements on startup than a closed loop system) normally cannot be driven by a PV powered pump. I also wonder if a differential control (Goldline style) does not do a better job of deciding when to turn the pump on (based on collector temperature AND storage tank temperature) than a PV driven pump, which just turns the pump on when there is enough sun to drive it? — Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Uncensored-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
Response:
I tend to agree with your doubt on a PV logic pump. When it is really cold out ans sunny your solar pump should be running top speed and you may be pumping warmer water to the collectors to radiate heat into the cold blue sky. It would seem to me on a very clear cold day we would need to only circulate slowly from the collectors in order to warm up the return water the most. There may be a phase lag where we would only be pumping below 0C solution back to the heat reserve when the sun first shines. Also there may be a nicely warmed roof/attic area capable of supplying more BTUs after the sun goes behind the clouds. Maybe some NiMh batts to may a delay from the bright sunshine. They need to charge before the pump starts and continue for 20-30 minutes after the sun goes away.
– Hide quoted text — Show quoted text -> I also wonder if a differential control (Goldline style) does not do a > better job of deciding when to turn the pump on (based on collector > temperature AND storage tank temperature) than a PV driven pump, which > just turns the pump on when there is enough sun to drive it? > — > Gary > www.BuildItSolar.com > "Build It Yourself" Solar Projects > —-== Posted via Newsfeeds.Com – Unlimited-Uncensored-Secure Usenet News==—- > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
Response:
Thanks for the various replies. I had previously checked out Thermo-dynamics, but I wrote off their solar pump. It looks and sounds nice, but the price tag isn’t. Hence the qualifier ‘affordable" in my original post….:) $700 for the pump, same for the pv panel, plus another $100 for a current booster, then add tax, shipping and whatnot. If I were not dead before being ahead in terms of power used, other parts of the hw system would probably be. Also, I emailed Thermo-dynamics a product enquiry and got no answer, so I was not impressed with them. I am not sure those pumps will deliver an adequate flow rate. Also, I did see the homepower mag article on drainback systems. It’s one of their technical downloads and very useful. One of the best info sources I found. On the w/e I spent a long time orienting and lining up my panels to ensure proper drainage. That took a lot longer than expected! I am planning to use gradual bends in 3/4" pipe in my system, no elbows, to reduce friction, plus ball shut-off valves that also provide an unrestricted bore when open. And probably the Taco pump. cheers, Rob
Response:
> Thanks for the various replies. I had previously checked out > Thermo-dynamics, but I wrote off their solar pump. It looks and sounds > nice, but the price tag isn’t. Hence the qualifier ‘affordable" in my > original post….:) $700 for the pump, same for the pv panel, plus > another $100 for a current booster, then add tax, shipping and whatnot.
I would think with that much invested you would be better off with the other solar energy source, wind… And actually have some real power, Of course, commercial power is so cheap in most of the developed world… Cheers, Jeff – Hide quoted text — Show quoted text -> If I were not dead before being ahead in terms of power used, other > parts of the hw system would probably be. Also, I emailed > Thermo-dynamics a product enquiry and got no answer, so I was not > impressed with them. I am not sure those pumps will deliver an adequate > flow rate. > Also, I did see the homepower mag article on drainback systems. It’s > one of their technical downloads and very useful. One of the best info > sources I found. > On the w/e I spent a long time orienting and lining up my panels to > ensure proper drainage. That took a lot longer than expected! I am > planning to use gradual bends in 3/4" pipe in my system, no elbows, to > reduce friction, plus ball shut-off valves that also provide an > unrestricted bore when open. And probably the Taco pump. > cheers, > Rob
Response:
Right..well, whether commercial power is really cheap is another vast debate. I guess by getting my panels going I will be will be doing something towards reducing power demand in the grand scheme of things. Anyhow….the latest is that I have found someone who has a decomissioned solar h/w system who has plumbing and pumps they are willing to give me for nothing, so that is what I will pursue. I filled and drain-tested my panels last night and all looked good. Even here in November at 46N the outlet pipes get too hot to touch when the sun is out. cheers Rob
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