Evacuated tube sizes & suppliers/manufacturers

[gorsuch]

A couple of questions before I start my new project.

1) Are the lengths and widths of vacuum tubes set in stone, or is it a case that you can basically buy any size you want? providing that is that you can find the right supplier/manufacturer.

2) To cut down on shipping costs and time in transit, has anybody dealt with, and hence got details of a good supplier/manufacturer based in Spain.


I will no doubt have a lot of other questions later on, but for now this is my starting point.

TIA

gorsuch

[cssolar]

swhs Spain

A couple of questions before I start my new project.

1) Are the lengths and widths of vacuum tubes set in stone, or is it a case that you can basically buy any size you want? providing that is that you can find the right supplier/manufacturer.

2) To cut down on shipping costs and time in transit, has anybody dealt with, and hence got details of a good supplier/manufacturer based in Spain.


I will no doubt have a lot of other questions later on, but for now this is my starting point.

TIA

gorsuch

Hi I deal in vacuum tube swhs here in the Costa Blanca area.

Vacuum tubes come in various sizes, one of the most common is 58mm x 1800mm

That is a standard size and will fit most Chinese units

they are available in single ( silver inside ) or triple target ( gold/red inside, more powerful )

A vacuum tube if filled with cold water will boil within 3 hours on a normal sunny day !

Good luck with your project !

I have swhs on my house and would never go back to gas or electric ( accept for back up )

Tony

[gorsuch]

I've never used the Triple target tubes, so what % heat generating wise are they better than the single silver coated ones.

If a tube of say 1800mm long produces x amount of heat, would a tube half the length produce only 50% the amount of heat of the longer one, or does it not work that way? I'm looking at using tubes of around 600mm if I can get away with it.

One for the techi guy's, what (roughly) kw per hour would a 1800mm tube generate in winter sun in the south of Spain.

Tony where are you situated on the CB, Nth or Sth.

gorsuch

[inetdog]

If a tube of say 1800mm long produces x amount of heat, would a tube half the length produce only 50% the amount of heat of the longer one, or does it not work that way? I'm looking at using tubes of around 600mm if I can get away with it.
gorsuch

Yes, as with solar PV, the amount of heat available is proportional to the area of the collector which is perpendicular to the sun. As long as you size the manifold and interconnections properly, one 600mm tube will produce about 1/3 of the heat of an 1800mm tube. But it will generally cost you more for the same amount of heat. Do you have limited space in which to install the shwh panels?

[gorsuch]

Thanks for the speedy reply inetdog, your info solves the first part of my problem, but I'm not actually creating a hot water system, I'm looking at using the heat that I can get from the end of the heat pipe, hence that's why I also need the kwph figure.

gorsuch

[cssolar]

I've never used the Triple target tubes, so what % heat generating wise are they better than the single silver coated ones.

If a tube of say 1800mm long produces x amount of heat, would a tube half the length produce only 50% the amount of heat of the longer one, or does it not work that way? I'm looking at using tubes of around 600mm if I can get away with it.

One for the techi guy's, what (roughly) kw per hour would a 1800mm tube generate in winter sun in the south of Spain.

Tony where are you situated on the CB, Nth or Sth.

gorsuch

Hi I am in the middle of the Costa Blanca inland of Alicante.

Shorter tubes will produce less energy.

I dont know too much technical stuff, only what I have learnt my self in 4 years of dealing with vacuum tube swhs.

When I placed two tubes in the sun filled with cold water one silver the other gold both boiled but the gold one boiled a bit faster and more violently than the silver one.

In the summer I dont worry about hot water in fact it is almost impossible to use it up ! average temperatures of 85 to 99 degrees centigrade.

In the winter the I still get plenty of hot water 55 to 65 degrees centigrade on normal cold but sunny days,
If like today ( Sunday ) the weather has been bad all day total overcast and rain my water temp is reading 42 tanks half full, so I have had to turn my back up gas boiler on ( but I must say its not often required )

I have found that by showering in the evening in winter is better because stored water temperature can drop over night.

Best Regards

Tony

[cssolar]

Thanks for the speedy reply inetdog, your info solves the first part of my problem, but I'm not actually creating a hot water system, I'm looking at using the heat that I can get from the end of the heat pipe, hence that's why I also need the kwph figure.

gorsuch

Just wondered what is your end application for the heat produced ?

Cheers Tony

[gorsuch]

Obviously the gold tube has the edge heat wise, so then it just becomes a case of price differential as to whether they are worth the extra money.

Yes we are well positioned in this area for solar (Torrevieja), I've had customers in the past that only used the back-up 2 or 3 times a year, and as you say!! in summer you just can't find cool water for love nor money.

gorsuch

[cssolar]

Obviously the gold tube has the edge heat wise, so then it just becomes a case of price differential as to whether they are worth the extra money.

Yes we are well positioned in this area for solar (Torrevieja), I've had customers in the past that only used the back-up 2 or 3 times a year, and as you say!! in summer you just can't find cool water for love nor money.

gorsuch

The suns back today, back up boiler in now off, and my swh tanks are three quarters full at 60 degrees, with underfloor heating pump on.


Yes gold tubes are a bit more expensive ( but not much ! )

Cheers Tony

[inetdog]

Thanks for the speedy reply inetdog, your info solves the first part of my problem, but I'm not actually creating a hot water system, I'm looking at using the heat that I can get from the end of the heat pipe, hence that's why I also need the kwph figure.

gorsuch

Well, there are two ways to approach this question. The first is to calculate the area (length time effective aperture) of the tube, multiply that by 1000w/m2 for "standard" insolation, then multiply by the nominal efficiency (typically rated at around 70% for evacuated tube) and then multiply be something like .8 to account for less than standard insolation. For an 1800 cm tube with a 5cm aperture this works out to roughly 90 watts per tube, or .09 KWH/hour x .7 x .5 = .04 KwH/H.
(your use of the units Kilowatts per hour is incorrect. The watt is a unit of power (energy delivered in unit time), so the unit of heat energy is the KwH. And the rate at which the tube delivers it is KwH/H = Kw.)

The other way to approach this, as a check, is to look at the rated BTU/Hour capacity of a manufactured panel. One BTU equates to .0003 KwH, so 4844 BTU/H (claimed for a representative 20 tube 1800cm panel) equates to 1.4 KwH/H or 70 wH/H per tube.