House near Rattanaburi, surin

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Re: House near Rattanaburi, surin

Postby tertim » Thu Aug 24, 2017 6:45 pm

[quote="Sometimewoodworker"][quote="tertim"]Hi qwerty

Assuming that you are just using the house pump, why would you need to use heat exchanger coils? I'm guessing that your system doesn't use them.
I'd be interested to understand the system you envision using the coils

HI SW
qwerty has stated that he wants to use a pressurized hot water tank and use a solar collector with HDPE pipe, the hot water tank he would like to use would mean the water pressure in the solar collector would be the cold water feed pressure, maybe 2 BAR plus in my opinion the LDPE pipe would not contain that pressure at temperatures in excess of 70c plus that is why a heat exchange coil is required here is sketch to give you an idea of the set up the only difference is the solar collector circuit would open vented and just contain plain water.

active_closed_loop_solar_wa.gif
active_closed_loop_solar_wa.gif (10.63 KiB) Viewed 349 times


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Re: House near Rattanaburi, surin

Postby Sometimewoodworker » Thu Aug 24, 2017 9:09 pm

tertim wrote:
Sometimewoodworker wrote:
tertim wrote:Hi qwerty

Assuming that you are just using the house pump, why would you need to use heat exchanger coils? I'm guessing that your system doesn't use them.
I'd be interested to understand the system you envision using the coils

HI SW
qwerty has stated that he wants to use a pressurized hot water tank and use a solar collector with HDPE pipe, the hot water tank he would like to use would mean the water pressure in the solar collector would be the cold water feed pressure, maybe 2 BAR plus in my opinion the LDPE pipe would not contain that pressure at temperatures in excess of 70c plus that is why a heat exchange coil is required here is sketch to give you an idea of the set up the only difference is the solar collector circuit would open vented and just contain plain water.

active_closed_loop_solar_wa.gif


Pop kan mai

That looks like a system designed for cold climate conditions and certainly would be a bit more complex to build.

I agree that using the LDPE pipe that is easily available (or HDPE if you can get it) specially with the fittings that are available might well not work very well at all.

On a different subject.
With the house plumbing you will also need to use pipes that are designed for hot water, Blue PVC isn't, there is a PPR pipe that is though the local shops probably won't have it in stock, there is also a metal/plastic composite pipe that I've seen in a few shops. You may get away with using the cold water PPR pipe if you make sure your water doesn't get too hot.

Also apart from the tank that he found at DoHome none of the standard water tanks are designed to be pressurised and the stainless steel tanks seem to develop leaks quite often.

I will not use a pressurised storage as it makes life much more difficult, a second pump on the hot water side is much easier to design and maintain
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Re: House near Rattanaburi, surin

Postby qwerty » Wed Sep 27, 2017 11:18 am

My hot water project has got off the ground – but only a little. I have been doing some testing, having bought 100 metres of 32mm diameter LDPE. At the moment it is in on a stone circle in the centre of the lawn.
The weather hasn’t been too good so far, although I have managed to get 60 degrees C coming out of the coil a couple of times.

Having given it some thought, I’ve come to the conclusion an open-vented system will probably be more practical.

Tertim, did you have any problem with water draining from the collector coil into the hot water tank, maybe causing it to overflow? Or perhaps you might have the top of the tank fairly tightly sealed, to prevent this?
I ask because your installation appears to have the collector perhaps two metres higher than the tank?
Obviously for thermo-syphon to work the hot water tank would be higher than the heat source.

For my installation to be practical I will have the same as you – the tank lower than the collector, by probably three metres.
The solar pump overcomes the thermo-syphon problem, but I was concerned if the coil might end up overflowing into the tank due to the height difference?
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Re: House near Rattanaburi, surin

Postby tertim » Fri Sep 29, 2017 9:30 pm

qwerty wrote:My hot water project has got off the ground – but only a little. I have been doing some testing, having bought 100 metres of 32mm diameter LDPE. At the moment it is in on a stone circle in the centre of the lawn.
The weather hasn’t been too good so far, although I have managed to get 60 degrees C coming out of the coil a couple of times.

Having given it some thought, I’ve come to the conclusion an open-vented system will probably be more practical.

Tertim, did you have any problem with water draining from the collector coil into the hot water tank, maybe causing it to overflow? Or perhaps you might have the top of the tank fairly tightly sealed, to prevent this?
I ask because your installation appears to have the collector perhaps two metres higher than the tank?
Obviously for thermo-syphon to work the hot water tank would be higher than the heat source.

For my installation to be practical I will have the same as you – the tank lower than the collector, by probably three metres.
The solar pump overcomes the thermo-syphon problem, but I was concerned if the coil might end up overflowing into the tank due to the height difference?


Hi qwerty
Pleased to hear your getting started on your project, firstly I would have thought that using 32mm pipe would be a little difficult to fix in place and would result in an overly large construction.

To answer your query the water doesn't drain from the collector coil when the pump switches off, the return pipe from the collector enters the hot water storage tank just below the the water surface level so in effect this becomes a sealed system (not sure if this is the correct terminology)
When a hot water tap is opened in the house, hot water is pumped from the tank, as the water level in the tank drops cold water is fed in via a float valve to maintain a constant level.

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Re: House near Rattanaburi, surin

Postby qwerty » Sun Oct 01, 2017 10:30 am

Hi Tertim,
Thanks for the reply.

I’m pleased you haven’t had any problem with the water draining from the collector coil. My main concern about it was my higher coil location of 3 metres compared to yours, given that my tank will be at ground level.
I think as well as the height difference, it could also depend on the quantity of water in the tank vs the quantity of water in the coil.

Yes, you’re right in assuming it is a larger construction.
The outer diameter of my collector coil is 2 metres. I went for 32mm as I will have 80 litres of solar heated water, before I get more involved with a tank.
I found a table on the internet listing the amount of water per metre for different pipe diameters, it shows that your coil has about 40 litres of water.

As I said, I’m going to do this step by step. The next stage is to make a frame to house the coil.
Looking at your photos, it seems you used a piece of steel plate as the base to house the coil? I was thinking of aluminium, as it won’t rust like steel, but I’m worried if I use aluminium it may bend under the weight of the water. This is because ideally to get the coil at the optimal inclination, I will need to raise it a couple of degrees higher than the pitch of the roof. Perhaps it isn’t that critical? My roof is that corrugated/ridged aluminium sheeting.
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Re: House near Rattanaburi, surin

Postby Klondyke » Sun Oct 01, 2017 1:53 pm

I found a table on the internet listing the amount of water per metre for different pipe diameters, it shows that your coil has about 40 litres of water.


If no table on hand (and 32 mm is the inner diameter, length 100m):

π*d*d/4 * l =
3.141 * 0.32*0.32/4 * 1000 (all in dm) = 80 dm3 = 80 l
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Re: House near Rattanaburi, surin

Postby tertim » Wed Oct 04, 2017 12:11 pm

[color=#0040FF]As I said, I’m going to do this step by step. The next stage is to make a frame to house the coil.
Looking at your photos, it seems you used a piece of steel plate as the base to house the coil? I was thinking of aluminium, as it won’t rust like steel, but I’m worried if I use aluminium it may bend under the weight of the water. This is because ideally to get the coil at the optimal inclination, I will need to raise it a couple of degrees higher than the pitch of the roof. Perhaps it isn’t that critical? My roof is that corrugated/ridged aluminium sheeting.[/quote]
[/color]


hi qwerty
Here's some pics of the underside of my collector, I used whatever materials i had to hand from my build 50x25x1mm galvanised tube and plywood shuttering it's very strong and even with your heavier pipe it should suffice.
If you don't intend fitting a tank at this stage how will you get the hot water into your house from your collector?

IMG_20171004_120840.jpg

IMG_20171004_120856.jpg

IMG_20171004_121038.jpg
Started painting before adding a lean to roof to the front for shade.
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Re: House near Rattanaburi, surin

Postby qwerty » Thu Oct 05, 2017 3:50 pm

Thanks for the photos of the underside of your collector.
I haven't managed to find a price for a sheet of aluminium here so far. Seeing prices for the US & UK, it might be too expensive, but I'll hang on until I find someone here to confirm one way or the other.

Before I get to fit a tank, for the next level of testing I was planning on putting the coil on the roof and pumping the domestic cold water around it and out to a tap.

See the photo of the coil I have so far, laying flat in the centre of the lawn on some slabs.
That can produce 60 degrees C, on the few sunny days we've had since I started this. That is using the same method of pumping cold water into the coil and measuring the temperature of the water at the tap you can see in the photo.
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