Overall piping length in swh systems

[saniconenergy]

Thank you for the reply saniconenergy.

I was actually interested in solar loop only - from the collectors to the storage tank (supply), and from storage tank to collector (return). Only the length of these pipes. Not the length of the pipes from the storage tank to water fixtures (bathroom, kitchen...).
I apologize for not mentioning this on the very beginning.

By the way, what happens if mentioned distance in your reply is larger than 100 feet? A stronger pump is needed?

"As quoted by Inetdog, lengthier the pipe is, more the energy losses occur in the Hot Water Loop. Now installing of thicker insulation would also help but to a certain extent. No matter how thick insulation I'm going to install, the bare minimum losses would always be in the range of 10-15%. So this leads us to wonder what to do in this case.

Either install a small POU of 1USG or 3 Liters at the usage point, which should take care of the comfort factor and the moment preheated water would start coming from the centralized solar/ hot water generation system, it would automatically cut off.

Or as mentioned earlier, install a demand driven system. However are experience says that depending on the design, you can easily get the payback of 18-24 months easily if compared with the cost of energy wasted in the recirculation loop."

[Solarbyryan]

Can't you just measure it? In places where soft copper is used, add in 10' for each 90 degree turn, in may be less, but I've learned having too much is better as removing soft copper from an attic or other enclosed space is tricky if you plan on reusing it for the same install.

If the enclosed space has alot of obstacles, add a few feet for each of the bends around things like HVAC systems and support beams.

Grab a long rope and mock run it the way you plan, mark where it bends and turns so you know what to buy, where to add length etc. The rope is great for long difficult to measure places. It won't be exact but you'll have an idea and you can decide where to add length. Goock luck!

[bernard]

Thank you for the information on new systems.

The biggest thing that happens when you have a run longer than 100 feet is that you waste both energy and water waiting for the heated water to get to the point of use and then letting it cool in the pipe.
A simple recirculating pump takes care of the user experience and water waste but makes the energy waste worse.

Isn't this (cooling the water which runs through pipes) something that can be solved with higher thickness of pipe insulation, and/or pipe insulation conductivity? Is it that expensive to increase the insulation thickness and decrease the insulation conductivity (change the insulation material)?

[inetdog]

Thank you for the reply saniconenergy.

I was actually interested in solar loop only - from the collectors to the storage tank (supply), and from storage tank to collector (return). Only the length of these pipes. Not the length of the pipes from the storage tank to water fixtures (bathroom, kitchen...).
I apologize for not mentioning this on the very beginning.

By the way, what happens if mentioned distance in your reply is larger than 100 feet? A stronger pump is needed?

The biggest thing that happens when you have a run longer than 100 feet is that you waste both energy and water waiting for the heated water to get to the point of use and then letting it cool in the pipe.
A simple recirculating pump takes care of the user experience and water waste but makes the energy waste worse.
There are more sophisticated systems that actually pump on demand from the hot water pipe back into the cold water pipe and then reverse the process to stuff the heated water back into the storage tank when you are done, but their cost and complexity may not make economic and ecological sense either.

[bernard]

Thank you for the reply saniconenergy.

I was actually interested in solar loop only - from the collectors to the storage tank (supply), and from storage tank to collector (return). Only the length of these pipes. Not the length of the pipes from the storage tank to water fixtures (bathroom, kitchen...).
I apologize for not mentioning this on the very beginning.

By the way, what happens if mentioned distance in your reply is larger than 100 feet? A stronger pump is needed?

[saniconenergy]

Sorry for copying the question by mistake



Considering that it's and 1000 sq yds residence & in ideal conditions the maximum distance for two-floor house, between Solar & last bathroom should be approximately 100 feet!

[bernard]

Thank you saniconenergy.

But there's no reply, it's just my initial starting reply copied.

[saniconenergy]

"There is one thing that I am curious of:
What are some rule of a thumb, or approximate overall pipe run length in residential swh systems?

I know it may be difficult to answer this question, as it depends on a lot of factors: whether or not a swh system's storage is right next to the collector (ICS, Thermo syphon), or located in the basement.
I also understand that it depends on the number of floors, position of a collector (on the roof, on the ground) and some other factors too.

But for example, what are some approximate values of piping lengths for ground floor + one/two floor houses with collectors on the roof, and storage tank in the basement or ground floor?
50 feet? 100 feet?
Can it be said for example: if your storage tank is located on the lowest floor, and collectors are on the roof then add the 20 feet of pipe length run (overall in both directions) per each story. Then add another 10 feet for the pipes on the roof.
Of course, this is an assumption based on a straight shot, from the storage to the collectors.

Just to clarify: I am not interested in losses of energy due to piping, nor in pipe diameters. I am just interested in the total pipe run length.

Thank you for the reply, and I apologize if it is difficult to answer this question."

MOD NOTE. If you have something to say then please make an "original" post. Do not just copy and paste and existing one.

[bernard]

Thank you.

[peakbagger]

One last time, the tank is in the basement, it runs through a first floor (which may be your ground floor) and then a second floor then into an attic where it then goes horizontal to line up with the collector connections and then vertical up through the attic and then up thru the roof to the slanted collectors.

[bernard]

My tank is in my basement ... two parallel pipe runs the are vertical for two stories ... two unequal length horizontal runs in my attic ...

Thank you peakbagger.
So just to see if I understood you correctly:

you have a basement, ground floor, first floor and an attic?

[peakbagger]

How many stories do you have? Basement and ground floor?
Where is the storage tank located? In the basement or ground floor (that's first floor in US I imagine). Are your collectors located on the roof?

My tank is in my basement, it uses a coil wrapped around a standard hot water tank (under the insulation jacket) rather than a heat exchanger. I have two parallel pipe runs the are vertical for two stories which is about 36 feet and then I have two unequal length horizontal runs in my attic to line up with the inlet and outlet of the SHW system on the pitched roof and then two unequal length vertical runs to get up to the inlet and outlet. I would guess around 70 feet total.

[Naptown]

Yes with a ruler

[bernard]

Thank you for the replies both organic farmer, Naptown.

We had an apartment building that was 3 stories tall. The furnaces for all units were in the basement...

What is the total pipe length run in your solar loop?

What you are concerned anout is flow or static head which is the friction caused ny elbows and length of pipe run.

I am not concerned about anything. Piping losses, size of the pump, pump consumption, flow rate, pipe diameters, insulation size, elbows etc. None of that.

I just wanted to know what is the total length run of your solar loop, supplied with information of number of stories.

Again, I understand every system is different, and it may also depend on the disposition of the pipes vertically (straight run from the tank to collectors or not), but there has to be some approximate rule of a thumb by which one can say approximately:
"three story building has a storage tank in the basement, collectors on a roof, I would say that your total pipe length run could be something like:"
4 stories (plus basement) * 20 feet ≈ 80 feet.

In reality the total pipe length run may be 60, or 100 feet, but I again it is still close enough to 80.

This is what I want to know.
I know there is not such formula, but based on a real life experiences of you solar how water experienced users, can it be derived approximately?

Thank you.

[Naptown]

We had an apartment building that was 3 stories tall. The furnaces for all units were in the basement. I had to replace the baseboard heating loops for all apartments. Apartments on the third floor were harder to pump water up into their loop, at the first, and for chasing the air bubbles out.

But once the loop was done, all the air bubbles were gone, and it was circulating, the circulating pump itself works no harder on the third floor units than they do for the second floor or first floor units.

For every foot of rise there is an equal foot of fall. It is a closed loop.

You can make a closed loop that is totally flat horizontal, and another loop that in the middle has to go up 40 foot and back done again. If both of these loops are the same length, diameter, and neither have any sharp bends, than resistance to flow will be the same.

The above is true.
Height only matters in an open loop or drain back system where there is no counter balancing effect of the fluid coming down the pipes offsets the rise.
And every system is different.
What you are concerned anout is flow or static head which is the friction caused ny elbows and length of pipe run.