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Solar water heater.
Posted: Thu Jan 10, 2019 9:21 pm
by Rwy in Sight
I am in the market for a solar water heater. I understand there are some characteristics, but I would welcome any advice from people having install such a unit previously.
I aim to acquire one with a 120 capacity, but beyond that I am open to suggestions.
Re: Solar water heater.
Posted: Thu Jan 10, 2019 9:48 pm
by Pontius Navigator
Where are you? If in UK I just don't see how the economics stack up. Quite some years ago we were given a quote of £4,000. My fuel bill at the time was high but included electric and gas. Gas covered central heating as well as water. The pay back would be well over 10 years.
Today my gas bill alone is £600 which includes heating and cooking. Hot water is perhaps £200-£250.
The problem in UK is the system is a heat exchanger system rather than direct. If you use expensive fuel to heat water it might be worthwhile.
Re: Solar water heater.
Posted: Fri Jan 11, 2019 12:18 am
by Alisoncc
Many many years ago once read that fluoride in drinking water corrodes aluminium. As most roof supported systems used to use very thin aluminium piping for it's lightness, meant they had a limited lifetime in areas with fluoridated water. Remember looking at the economics, and payback time exceeded lifetime of system. Don't know if that is still the case.
Alison
Re: Solar water heater.
Posted: Fri Jan 11, 2019 12:30 am
by Slasher
RiS our resident solar powerist Ex-Ascot would be the best bloke to talk to.
Re: Solar water heater.
Posted: Fri Jan 11, 2019 1:13 am
by Sisemen
Had solar hot water for a number of years in both houses. Nothing but praise - mind you, we do actually have sunshine in this neck of the woods!
Only practical advice I would give is go for a quality product that has a solid name. Cheapies will let you down eventually.
Re: Solar water heater.
Posted: Fri Jan 11, 2019 7:28 am
by Rwy in Sight
Thanks for the wise words. I am currently renting an apartment and as a part of the deal, I shall install such a heater in exchange of a lower rent. The area where I live has plenty of sunshine and from where I sit I can see at least a couple of units. I am not in the balcony.
Alisonc, I don't know about the water. Most systems offer a 5 year warranty and I intend to follow the maintenance requirements.
Re: Solar water heater.
Posted: Fri Jan 11, 2019 9:35 am
by Alisoncc
Rwy in Sight wrote: ↑Fri Jan 11, 2019 7:28 am
Alisonc, I don't know about the water. Most systems offer a 5 year warranty and I intend to follow the maintenance requirements.
RiS, from my perspective the issue was the "Return on investment". If the system saved "x" number of pounds per year in utility bills, had a total cost of "y" pounds, but had a lifetime of number of years times the annual savings significantly less than "y". Then it would be economically unviable.
Alison
Re: Solar water heater.
Posted: Fri Jan 11, 2019 5:37 pm
by Rwy in Sight
Alison,
I save a small amount of money each month - the landlady has accepted to receive a lower rent and I would save money in utility bills. I don't really care to leave behind a solar water heater that would have a longer life than let's say five years which is a good initial term for renting a house. So my calculations are a bit different although yours are essentially correct assuming Y overpasses X before the end of its lifetime.
Re: Solar water heater.
Posted: Fri Jan 11, 2019 7:47 pm
by Pontius Navigator
Alison, the pipe weight would be insignificant when compared with the water tank, assuming a roof mounted system as in a direct heat system. The 'wonderful ' systems in quarters in Cyprus in 1970s were out of commission in 2000s.
Re: Solar water heater.
Posted: Sat Jan 12, 2019 1:22 am
by Alisoncc
Alisoncc wrote: ↑Fri Jan 11, 2019 12:18 am
Many many years ago once read that
fluoride in drinking water corrodes aluminium. As most roof supported systems used to
use very thin aluminium piping for it's lightness, meant they had a limited lifetime in areas with fluoridated water.
Re: Solar water heater.
Posted: Sun Jan 13, 2019 8:28 am
by Rwy in Sight
I have not considered aluminium piping. I think we use copper here.
Re: Solar water heater.
Posted: Wed Jan 16, 2019 1:15 pm
by Ex-Ascot
Sorry RiS only just seen this thread. We have a fantastic system see below. It comprises of black glass tubes. Never seen it in Greece though. Even in weak sunshine it produces very hot water. The tank is well insulated and will maintain the water hot for days. It would be fine for your monthly shower.
You know that you are very welcome to visit and inspect it. Doesn't even require you to get on a ship. Can't remember the cost but it wasn't expensive. Can look it up for you if you wish.
Re: Solar water heater.
Posted: Tue Jan 29, 2019 8:44 pm
by Rwy in Sight
I acquired a normal one (one with a metal frame) I have not used the initial supply of water yet - only used about 4 or five times and it gives a decent temperature even if it is still winter here. The cost was 550 € for the unit with a 3 m2 collector and another 250 (without a VAT receipt) for the installation.
Re: Solar water heater.
Posted: Sun Jul 09, 2023 10:07 pm
by John Hill
Ex-Ascot wrote: ↑Wed Jan 16, 2019 1:15 pm
We have a fantastic system see below. It comprises of black glass tubes.
We have one like that roof mounted with an electric pump to push the hot water down to the storage cylinder, it works very well at Lattitude 44.
However the glass tubes do not contain water, (at least in our system), the sun heats a copper tube which has liquid inside (glycol or what-have-you). The liquid heats much hotter than 100C and rises up the tube to where it heats the water.
Downside (apart from being expensive) the hot tubes can overheat and burst so you loose that tube and there is nothing to tell you. Eventually when you think something is wrong and a man has to come and check it out. He gives you the bad news and then you are faced with expense of replacement tubes but that is only after you find someone who will supply them.
Re: Solar water heater.
Posted: Wed Jul 12, 2023 10:09 pm
by llondel
I'm about to experiment with solar heating for the pool - crude set-up to start with, 100ft of black PVC tubing and an aquarium pump. Circulate pool water through the tubing which is left in sunlight, and see what temperature increase I see.
Re: Solar water heater.
Posted: Wed Jul 12, 2023 10:22 pm
by Karearea
llondel wrote: ↑Wed Jul 12, 2023 10:09 pm
I'm about to experiment with solar heating for the pool - crude set-up to start with, 100ft of black PVC tubing and an aquarium pump. Circulate pool water through the tubing which is left in sunlight, and see what temperature increase I see.
^ that should work very well; had a pool some years ago and did exactly that, I think the water-temperature ended up being about 27°C
Pool was 50' long from memory, in-ground, and the extra hose was incorporated into the pool's main pump system.
Re: Solar water heater.
Posted: Mon Aug 21, 2023 12:52 pm
by OFSO
Llondel, our black PVC mains water tubing perforates in one to two years here when exposed to direct sunlight. Pinhole leaks.
I've just changed a length of the same pipe indoors, dated 1996, which split end to end.
Re: Solar water heater.
Posted: Mon Aug 21, 2023 5:02 pm
by Pontius Navigator
llondel, I had some commercial dome heaters. Water was taken from the pool pump outlet, passed through a filter, through an inline electric heater, to the pair of dome heaters.
The dome heaters had a conical spiral of black ridged tubing. Heated water was fed back to the pool.
With that setup ensure the pool pump is off when the is no solar heating else the pool will heat the air.
I needed to use electric power at cheap rate overnight and solar by day. I considered automatic switching but instead opted for a manual setup. At night the solar was isolated. By day the electric switched off with a time switch. Worked well.
Unfortunately, as OFSO says, the black tubing fails. The tubing was a hard rigid plastic as the spiral radius tightened there was stress on the tube.
Re: Solar water heater.
Posted: Tue Aug 22, 2023 3:21 am
by Karearea
The tubing I'm familiar with was probably a 20mm or 25mm heavy-duty alkathene pipe.
Had hundreds of metres of this on the ground elsewhere for irrigation water-supply, for a couple of decades.
If it froze it would blow connecting fittings apart but never split.
Exposed to very high summer temperatures in full sun.
Never had any leaks in the pipe itself.
Re: Solar water heater.
Posted: Tue Aug 22, 2023 7:26 am
by Pontius Navigator
For pool heating the other issue is space. If confined the domes were good, up to a metre square each. By definition though half were at the back from the sun.
One home made one I heard of was a black painted barrel, pipe coiled in the barrel, barrel filled with water.
Another system, Walmart I think, was water panels on a roof. Not sure the flow method.