Hot Water System

"Space yes
Extra weight wanted aloft no."

The box to hold the tubing is light weight and most of the added weight is whatever 50 ft of copper tubing weigh filled with water, plus a piece of glass.

50 lbs aloft to have unlimited hot water (when the sun shines) would not seem destableizing.

50ft of tube would only give a few litres of water yes?
I doubt it works as instant hot water so what happens when the few litres of hot water is out of the tubes?

Logic would suggest that you're circulating your solar warmed water through your water heater, so you then have a water heater full of warm water.

These guys provide kits and a pretty good explanation on how it works
Heliatos Solar

Simi 60 said:

50ft of tube would only give a few litres of water yes?
I doubt it works as instant hot water so what happens when the few litres of hot water is out of the tubes?

Click to expand...

"50ft of tube would only give a few litres of water yes?"

Which is then pumped into your existing HW heater , all day long.

The price is the small DC pump and the aquastat to turn the circulation on.

While one can not create a home brew PV systen ,home making solar hot water has at least a 75 year history in southern US states.

CBS , cruse but simple actually does work.

OK, I see we are talking a different type of solar to what I was thinking on the roof.
I was thinking of these types which, would be to much weight aloft.



Seeing as we are talking about just the panel on the roof with remote storage tank, am I right that you were thinking I could use the existing insulated copper tank from the existing HWS for storage?

The first hurdle I see there is that tank is down near the engine room and the roof where the panels would go is near 30ft above it so a fair bit of pump would be required to circulate that water.
A quick google would suggest that the pump alone would be well on the way to the cost of a 45 litre Force10 HWS, which, as it would replace the existing large domestic HWS would be a relatively simple install (water circuit and power is already there) and would free up storage space.

The second is, based on my household solar HWS experience where I turned off the electric heating side of it, what happens when its raining for more than a few days?
Without an alternative heat source it was back to cold showers.

FAQ on the Heliatos site says "What happens at Dark?
First you use the water that was heated by the sun during the day. Then if you need more hot water then your gas or electric will kick in."

So I still need electric or gas in addition to the solar for the times when its raining which has been several days where I am now and cold as well.
Based on that I feel I am better off going electric and an extra $300 for 500 watts of solar panels in the space that the solar hot water panels would have gone.

The solar setup is an ADDITION to the existing insulated copper tank from the existing HWS for storage

It just stops the need for a noisemaker to make HW, on nice days

Parts are not that expensive , here is one circ pump.

https://www.amazon.com/GPM-Solar-Hot-Water-Pump/dp/B005EU7ONM

OF course all solar devices have limits to output depending on size.

If you require 100G of HW a day it wont work.

For non mental health showers and dish washing or 10-maybe 15G of hot water a day ,

If the engine heats the water it will be very hot. therefore your showers will use mostly cold water until it cools. Just be careful of the how water. The handle shut off valves allow hot water to backflow a bit into the cold pipes and when first opened again the water may be too hot.
With a5 or 6 gallon hot water tank we got two days of showers before needing more heat.

The advice above to try what you have first is spot on.

FF said:

Parts are not that expensive , here is one circ pump.

https://www.amazon.com/GPM-Solar-Hot-Water-Pump/dp/B005EU7ONM

,

Click to expand...

Thats no good
Only pumps a 9ft head
I would need one that does 30ft at least and they are quite expensive.

That, in addition to the panels linked to earlier will cost a lot more than a 45 litre electric.

bayview said:

If the engine heats the water it will be very hot.

Click to expand...

If the engine only runs once a week and their is no calorifier attached the water wont be hot at all.

The advice above to try what you have first is spot on.

Click to expand...

And I did say I would try that but given the size t and age of the existing unit I'd better start preparing for the replacement.

$200
SID10PV

Simi 60 said:

Thats no good
Only pumps a 9ft head
I would need one that does 30ft at least and they are quite expensive.

That, in addition to the panels linked to earlier will cost a lot more than a 45 litre electric.

Click to expand...

sean9c said:

$200
SID10PV

Click to expand...

Product Specifications:
• 10 Watt
• Max Head 3.5 ft
• Max Flow 3.3 gpm
http://shop.solardirect.com/product_info.php?cPath=69_71_84_72_73_268&products_id=1273

I did say I need one that pumps a 30ft head

"Thats no good
Only pumps a 9ft head
I would need one that does 30ft at least and they are quite expensive."

HEAD is how high a pump can lift a column of water.

Circulating water in a closed loop is mostly a skin friction and fitting resistance energy consumer , unlike lifting.

True hot water rises and cold sinks , but the energy to force heated water down is very minor.

For no real money you could lay out 50-100ft of dark hose on the cabin top and use a spare galley pump to see how much heat is added to the existing setup.

Only 2 T's and a check valve would be required.

100ft of 3/4 hose might be enough volume of water by itself for a shower.

FF said:

HEAD is how high a pump can lift a column of water.

Click to expand...

Yes, and the roof, where the panels or black hose will be is 30 ft above the storage tank/existing HWS
<<< Look to the left <<<

For no real money you could lay out 50-100ft of dark hose on the cabin top and use a spare galley pump to see how much heat is added to the existing setup.

Click to expand...

And then where will I put my 9 x 260w solar panels?

100ft of 3/4 hose might be enough volume of water by itself for a shower.

Click to expand...

It probably would be, but then what happens when others want a shower?
What happens when it raining for day or 3?
I'll need to fire up an electric HWS right?

"I'll need to fire up an electric HWS right?"

You bet.

Solar is for modest HW requirements in nice sunshine.

It is an augment to what the big for heavy requirements system can do.

The point is with solar a couple can easily live , well, with no main engine or noisemaker.

The big power hog is usually the reefer , if you can make and store HW while feeding that beast you are home free.

We use propane to keep the ice cream hard and beer cool, so our big energy hog is the battery bank loosing a few percent each day, which solar handles for us.

Head of Water spec on pump is not really relevant. It would be if you had an open ended pipe, so the water was pouring out the end. What you're looking at is a closed loop system where water is going up to the solar panel and then back down. In that system, once it's full, the weight of the water going down is equal to the weight of the water going up. So as the water flows down on one side it pulls the water up on the other side. The pump keeps the motion going and has to provide some energy to overcome the friction loss in the tubing. The length of the tubing not the height will determine pump size. There are formulas to calculate this. That pump would be adequate for about 100ft of 1/2" tube.

Simi 60 said:

Product Specifications:
• 10 Watt
• Max Head 3.5 ft
• Max Flow 3.3 gpm
El Sid DC Voltage Solar Pump SID10PVSS

I did say I need one that pumps a 30ft head

Click to expand...

sean9c said:

That pump would be adequate for about 100ft of 1/2" tube.

Click to expand...

So 30ft up in a dark locker and 30ft down in a dark locker leaves 40ft to see the actual light of day.
Doesnt sound like much

Sounds like you're just being obtuse.
Good luck

Simi 60 said:

So 30ft up in a dark locker and 30ft down in a dark locker leaves 40ft to see the actual light of day.
Doesnt sound like much

Click to expand...

FF said:

"I'll need to fire up an electric HWS right?"

You bet.

Solar is for modest HW requirements in nice sunshine.
It is an augment to what the big for heavy requirements system can do.

Click to expand...

And this is my point.
Going the solar route I need two installations to make it work.

The point is with solar a couple can easily live , well, with no main engine or noisemaker.

The big power hog is usually the reefer , if you can make and store HW while feeding that beast you are home free.

Click to expand...

The point is that the roof space will have solar panels for generating electricity.
On the solar quote it was recommended 6 x 250 and I am going 9 x 250 (an extra $450)
Should be more than enough to run the refrigeration and probably a small 45L HWS so no "noisemaker" required.

On the days of no sun I would think feeding a 45L HWS would require far less "noise" than if I was feeding 140L HWS.

sean9c said:

Sounds like you're just being obtuse.
Good luck

Click to expand...

How so?
Solar HWS requires sun
You say the pump is good for 100ft, 60ft of which will never see sun.
Is 40 ft of sun drenched tube enough to make a solar HWS work?

I dont want to waste time and $$ dicking around with something that is a "maybe"