If former forum member hawkerj96 is still visiting, please contact admin as we have a new member who wishes to contact you about John Hawke

Solar water heater.

Message
Author
User avatar
Rwy in Sight
Chief Pilot
Chief Pilot
Posts: 6725
Joined: Wed Aug 26, 2015 8:04 pm
Location: Lost in an FIR somewhere
Gender:

Solar water heater.

#1 Post by Rwy in Sight » Thu Jan 10, 2019 9:21 pm

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.

Pontius Navigator
Chief Pilot
Chief Pilot
Posts: 14669
Joined: Fri Jul 07, 2017 8:17 am
Location: Gravity be the clue
Gender:
Age: 80

Re: Solar water heater.

#2 Post by Pontius Navigator » Thu Jan 10, 2019 9:48 pm

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.

User avatar
Alisoncc
Chief Pilot
Chief Pilot
Posts: 4260
Joined: Sat Aug 22, 2015 7:20 am
Location: Arrakis
Gender:
Age: 80

Re: Solar water heater.

#3 Post by Alisoncc » 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. Remember looking at the economics, and payback time exceeded lifetime of system. Don't know if that is still the case.

Alison
Rev Mother Bene Gesserit.

Sent from my PDP11/05 running RSX-11D via an ASR33 (TTY)

Slasher

Re: Solar water heater.

#4 Post by Slasher » Fri Jan 11, 2019 12:30 am

RiS our resident solar powerist Ex-Ascot would be the best bloke to talk to.

Sisemen

Re: Solar water heater.

#5 Post by Sisemen » Fri Jan 11, 2019 1:13 am

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.

User avatar
Rwy in Sight
Chief Pilot
Chief Pilot
Posts: 6725
Joined: Wed Aug 26, 2015 8:04 pm
Location: Lost in an FIR somewhere
Gender:

Re: Solar water heater.

#6 Post by Rwy in Sight » Fri Jan 11, 2019 7:28 am

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.

User avatar
Alisoncc
Chief Pilot
Chief Pilot
Posts: 4260
Joined: Sat Aug 22, 2015 7:20 am
Location: Arrakis
Gender:
Age: 80

Re: Solar water heater.

#7 Post by Alisoncc » Fri Jan 11, 2019 9:35 am

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
Rev Mother Bene Gesserit.

Sent from my PDP11/05 running RSX-11D via an ASR33 (TTY)

User avatar
Rwy in Sight
Chief Pilot
Chief Pilot
Posts: 6725
Joined: Wed Aug 26, 2015 8:04 pm
Location: Lost in an FIR somewhere
Gender:

Re: Solar water heater.

#8 Post by Rwy in Sight » Fri Jan 11, 2019 5:37 pm

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.

Pontius Navigator
Chief Pilot
Chief Pilot
Posts: 14669
Joined: Fri Jul 07, 2017 8:17 am
Location: Gravity be the clue
Gender:
Age: 80

Re: Solar water heater.

#9 Post by Pontius Navigator » Fri Jan 11, 2019 7:47 pm

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.

User avatar
Alisoncc
Chief Pilot
Chief Pilot
Posts: 4260
Joined: Sat Aug 22, 2015 7:20 am
Location: Arrakis
Gender:
Age: 80

Re: Solar water heater.

#10 Post by Alisoncc » Sat Jan 12, 2019 1:22 am

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.
Rev Mother Bene Gesserit.

Sent from my PDP11/05 running RSX-11D via an ASR33 (TTY)

User avatar
Rwy in Sight
Chief Pilot
Chief Pilot
Posts: 6725
Joined: Wed Aug 26, 2015 8:04 pm
Location: Lost in an FIR somewhere
Gender:

Re: Solar water heater.

#11 Post by Rwy in Sight » Sun Jan 13, 2019 8:28 am

I have not considered aluminium piping. I think we use copper here.

User avatar
Ex-Ascot
Test Pilot
Test Pilot
Posts: 13065
Joined: Mon Aug 24, 2015 7:16 am
Location: Botswana but sometimes Greece
Gender:
Age: 68

Re: Solar water heater.

#12 Post by Ex-Ascot » Wed Jan 16, 2019 1:15 pm

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. :YMPARTY: 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.
Attachments
Solar Geyser.jpg
'Yes, Madam, I am drunk, but in the morning I shall be sober and you will still be ugly.' Sir Winston Churchill.

User avatar
Rwy in Sight
Chief Pilot
Chief Pilot
Posts: 6725
Joined: Wed Aug 26, 2015 8:04 pm
Location: Lost in an FIR somewhere
Gender:

Re: Solar water heater.

#13 Post by Rwy in Sight » Tue Jan 29, 2019 8:44 pm

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.

John Hill
Chief Pilot
Chief Pilot
Posts: 5674
Joined: Sun Aug 23, 2015 7:40 pm
Location: Aotearoa

Re: Solar water heater.

#14 Post by John Hill » Sun Jul 09, 2023 10:07 pm

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.
Been in data comm since we formed the bits individually with a Morse key.

User avatar
llondel
Chief Pilot
Chief Pilot
Posts: 5881
Joined: Wed Oct 03, 2018 3:17 am
Location: San Jose

Re: Solar water heater.

#15 Post by llondel » 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.

Karearea
Chief Pilot
Chief Pilot
Posts: 4723
Joined: Thu Sep 10, 2015 5:47 am
Location: The South Island, New Zealand

Re: Solar water heater.

#16 Post by Karearea » Wed Jul 12, 2023 10:22 pm

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.
"And to think that it's the same dear old Moon..."

User avatar
OFSO
Chief Pilot
Chief Pilot
Posts: 18563
Joined: Sat Aug 22, 2015 6:39 pm
Location: Teddington UK and Roses Catalunia
Gender:
Age: 80

Re: Solar water heater.

#17 Post by OFSO » Mon Aug 21, 2023 12:52 pm

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.

Pontius Navigator
Chief Pilot
Chief Pilot
Posts: 14669
Joined: Fri Jul 07, 2017 8:17 am
Location: Gravity be the clue
Gender:
Age: 80

Re: Solar water heater.

#18 Post by Pontius Navigator » Mon Aug 21, 2023 5:02 pm

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.

Karearea
Chief Pilot
Chief Pilot
Posts: 4723
Joined: Thu Sep 10, 2015 5:47 am
Location: The South Island, New Zealand

Re: Solar water heater.

#19 Post by Karearea » Tue Aug 22, 2023 3:21 am

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.
"And to think that it's the same dear old Moon..."

Pontius Navigator
Chief Pilot
Chief Pilot
Posts: 14669
Joined: Fri Jul 07, 2017 8:17 am
Location: Gravity be the clue
Gender:
Age: 80

Re: Solar water heater.

#20 Post by Pontius Navigator » Tue Aug 22, 2023 7:26 am

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.

Post Reply