solar hot water

[barge sara]

If you want to know more about solar thermal (or anything else....), ask a qualified professional.

 

and there was me thinking that was what discussion forums were for.......

[ditchcrawler]

How about house installations then?

normally a solar powered pump

 

Ah, good old myth is alive and well, but a little knowledge is a dangerous thing when playing with steam and boiling water.

 

If you want to know more about solar thermal, ask a qualified professional.

 

Having read the various stories about vandalism on canals, the only thing stopping me installing a system is the risk of damage.

I think Danial knows quite a bit about steam and boiling water

[WotEver]

I think Daniel knows quite a bit about steam and boiling water

Yeah, I think he does

[Smelly]

I quite fancy trying this one and there's some good discussion of the science bits in the comments.

[Bobbybass]

I did find an interesting homemade unit on a US website..but can't find the link...

THe guy had bought a big coil of the black irrigation hose.....about 100 feet a think..?....It was about 8mm diamter...and designed to be exposed to heat and UV rays....

He basically left it ccoiled...and placed it under glass with foil below it......

I think he reckoned that it held several gallons...and he just had this 'in line' with his hot water feed....

I do recall that he said to use brass joiners as the plastic ones didn't survive the heat...

Another one on the site used the black fins from the back of an old fridge...

 

Interesting stuff...

 

Bob

[Smelly]

I did find an interesting homemade unit on a US website..but can't find the link...

THe guy had bought a big coil of the black irrigation hose.....about 100 feet a think..?....It was about 8mm diamter...and designed to be exposed to heat and UV rays....

He basically left it ccoiled...and placed it under glass with foil below it......

I think he reckoned that it held several gallons...and he just had this 'in line' with his hot water feed....

I do recall that he said to use brass joiners as the plastic ones didn't survive the heat...

Another one on the site used the black fins from the back of an old fridge...

 

Interesting stuff...

 

Bob

 

Read my link...

 

Is that like "eat my dust" in nerd terms I wonder?

Edited June 21, 2010 by Smelly

[Roger Gunkel]

There are many ways to make solar hot water systems based on old fridge radiators, car radiators, black bin liners, copper tubes, lemonade bottles etc etc. Unfortunately, they all rely on hot or warm summer days to get decent results, if you want warm water in the Autumn, Winter or Spring, then they are all pretty useless in this country. If you just want quite hot water on a sunny summers's day, get a 20 litre black plastic waste water container from a caravan shop, stick it on the roof for a few hours and you will have very warm water.

 

If you want anything for serious hot/warm water all year round, then you need evacuated solar tubes. They are rather like the ones in the photo on the roof of the boat a few posts back. That one though, had the hot water tank above the tubes, making it big and cumbersome and not so good in the cold weather due to heat loss from the tank. Evacuated tubes, come in two types, but the most practical for UK use consist of a sealed pyrex double skinned tube, rather like a transparent thermos flask tube. Through the middle runs a copper pipe that is filled with an antifreeze liquid or gas. The sun shines through the pyrex heating the inner copper pipe and the heat is transferred from the tube to a heat exchanger manifold that the bulb shaped top of the pipes plug into. The anti freeze in the manifold heats up and is pumped to a calorifier loop in the hot water tank, where it transfers heat to the water. A small pump is used to circulate the warm antifreeze, and sensors in the tube manifold and the hot water tank switch the pump on when there is a relevant higher temperature difference in the manifold.

 

The advantage of the evacuated tubes is that the heat absorbed in the copper tube, is protected by the vacuum surrounding it, so they work even in Winter sun. Also as a boat hot water tank is usually a lot smaller than a house one, a much smaller area of tubes can be used. Providing the tubes are set at a reasonable angle towards the sun, they don't need to be at 45 degrees like the one in the picture, as they are quite tolerant to lower angles. They could also be protected against vandalism by making a clear acrylic cover over them.

 

Roger

[johnmck]

Hi

 

I intalled a Viessman evacuated tube solar system on my previous property, a bungalow with a south facing roof. This system had no "Wet" connections on the roof as each tube ended in a copper condenser, which plugged into an insulated copper manifold. This was a sealed system containing anti-freeze. As soon as the temperature in the manifold exceeded the temperature in the tank,by several degrees, the pump started.

 

I had this system for four years. No maintanance, and free hot water for all needs march to october. Yes i had to occasionally flick on the gas boiler on poor harvest days, but even in mid winter, on a sunny day there was solar gain. My present property is unsuited to this system, but my next will be. British gas even came and changed my meter as my gas consumption dropped so much and they thought it was faulty! I had to manage water usage but due to the size of the hot water cylinder, never ran out at a critical time.A display informed you of all functions.

It even helped sell the property!

As for a boat, well just too fragile i would think.

 

John

Edited June 21, 2010 by johnmck

[Proper Job]

How robust are the Pyrex tubes?

 

I can see that working with a house is fine, what about vibration from engines, clouting the odd wall etc?

[Shippo]

How robust are the Pyrex tubes?

 

I can see that working with a house is fine, what about vibration from engines, clouting the odd wall etc?

 

hi the tubes are pretty robust mine have taken a good few knocks, not sure if i should put a perspex cover over them, or that may make the water even hotter, and that is the problem im having at the mo,

as soon as the tank reaches 60deg the solar pump turns off to switch to a cooling finrad and pump that i dont have, mine just boils at the top and steams out of the pressure release valve,

i can change it to 70 or 80deg in the tank but how hot is the tank allowd to get before its dangerous? and shoud i have a pressure release valve on the calorifier? dont know if it will get to 80deg but i didnt think it would get to 60deg.....

[stuart]

i can change it to 70 or 80deg in the tank but how hot is the tank allowd to get before its dangerous?

 

Most people who use their engine to heat the hot water tank will have a water temperature of at least 80 degrees.

 

Shoud i have a pressure release valve on the calorifier?

 

Yes absolutely! If you don't you've created a bomb - at some point the water will expand and if your lucky blow a connection in the pipe work, if your unlucky the tank will explode covering everything and everyone in almost boiling water!!

Edited June 22, 2010 by stuart

[Shippo]

Most people who use their engine to heat the hot water tank will have a water temperature of at least 80 degrees.

 

 

 

Yes absolutely! If you don't you've created a bomb - at some point the water will expand and if your lucky blow a connection in the pipe work, if your unlucky the tank will explode covering everything and everyone in almost boiling water!!

 

thaught i should have a pressure release valve, but there wasnt one on when i brought the boat, would have thaught the boat builder would have put one on

[Artimis]

Hence my warning. If you intend playing, you are risking damage and injury. Did you know that when steam flashes over, it expands to 1600 times its water volume, so a burst pipe will fill a cabin with scalding steam.

 

All unvented systems must be installed and commisioned by a qualified person by law for this reason.

[RLWP]

Hence my warning. If you intend playing, you are risking damage and injury. Did you know that when steam flashes over, it expands to 1600 times its water volume, so a burst pipe will fill a cabin with scalding steam.

 

All unvented systems must be installed and commisioned by a qualified person by law for this reason.

 

Speaking of flashing over, what is going on in your avatar?

 

Richard

[Justme]

Poss needs a pressure vessel too.

[paulcatchpole]

Hence my warning. If you intend playing, you are risking damage and injury. Did you know that when steam flashes over, it expands to 1600 times its water volume, so a burst pipe will fill a cabin with scalding steam.

 

All unvented systems must be installed and commisioned by a qualified person by law for this reason.

 

G3 ticket, yes, in a residence. Usually needs building control approval too.

 

On a boat, like anything, just get it right. Most things in life aren't that hard if you can actually apply some common sense.

 

PC