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Space Heating


leaves
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The old schools had those water radiators for heat, with a boiler.

 

Wonder if you can do the same with EV tubes, first heat your geyser and then circulate the water to these radiators.

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Ok, so the guys in Europe are way ahead with this one.

 

The old type of thinking is to use wall heaters, more like radiators. Problem is these units take room space, wall space and heats the room unevenly.

Advantage is it can be installed after a house was already constructed.

 

Underfloor heating is more expensive than wall heaters, but the room heating is even throughout.

Also, water temp for underfloor heating is a bit lower than radiators.

 

Now, how to physically do it?

If you look at overseas homes, you will normally find a utility room in the house. All alternative energy services are housed here.

The "geyser" is normally a huge upright unit and around 500L and more, depending the home size.

 

Heating is done via many different sources like gas, solar and wood stove.

The wood stove is great. It generates heat inside the house and heat water at the same time!

 

The advantage of having an upright heater tank is a phenomenon known as stratification.

Basically it means water will settle in the tank in different layers. Hottest water at the top and colder water at the bottom.

Hot water for washing and shower is taken from the top of the tank.

40 Degree water for heating is taken from around the middle of the tank.

Heat exchangers are also used to make sure the water going out is at a constant set temperature.

By taking lower temp water for heating, you still left with hotter at the top for washing.

 

EV tubes are great for heating water. I would suggest using a decent pumped system to make sure you get the most out of your system.

Normal thermoshypen will circulate the water so fast, you going to end up with water all at the same temp in the tank.

This also applies to circulating pumps running directly from solar panels.

A decent controller will monitor your EV temp and only start the pump once the EV temp is say 8 degrees higher than the water in your storage tank.

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I would suggest using a decent pumped system to make sure you get the most out of your system.

Normal thermoshypen will circulate the water so fast, you going to end up with water all at the same temp in the tank.

This also applies to circulating pumps running directly from solar panels.

A decent controller will monitor your EV temp and only start the pump once the EV temp is say 8 degrees higher than the water in your storage tank.

 

Hi Wetkit, i always thought that the thermosyphon system will have a much smaller effect on the stratification layer as the flow rate is typically very small.

 

I always understood that as the thermosyphon system works on the gravity differences of the water, that the resultant force to drive the water is quite small. Therefore one should use pipes with large cross sectionall area (22 mm rather than 15mm), short pipe length and the pipe should be as straight as possible. (To reduce the resistance to flow)

 

With a controller system i feel that you could easily pump for too long as there is a thermal lag in measuring the temperature correctly. This in addition to the high flow rate of the pump will surely result in more mixing in the tank and consequently a negative effect on your stratification layer. 

 

These are just my thoughts.

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Dear leaves,

 

It is one of my unfinished projects but what I have done so far is to built 1.2m x 2.4m woden boxes, just the size of a whole sheet of plywood and run a flexible aluminium tubing (150mm if memory serve me right) and closing it all up with glass or other tranparent material. I have built two such boxes so far.

 

Now the finishing part, I have to find a fan to push air from the room air to this solar box, and out on the other side comes hot air... hopefully the fan can be solar powered directly so when the sun is out it is working autonomously. 

 

Something along this lines(is where I got the idea from):

 

https://sites.google.com/site/glenssolarheater/

 

or

 

http://www.builditsolar.com/Projects/SpaceHeating/DownSpout/DownSpout.htm

 

And I think you should review all this great website called Built it solar (I considered it the bible of solar DIY), starting from here:

 

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

 

 

Warm regards from Sunny southern Spain!

 

Gustavo

 

 

 

 

Hi Guys

Whag is the best way to use solar for space heating?
It seams like heating water with flat panels and using a heat exchanger to circulate the warm air into your living space?
Thanks
L

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Hi Wetkit, i always thought that the thermosyphon system will have a much smaller effect on the stratification layer as the flow rate is typically very small.

 

I always understood that as the thermosyphon system works on the gravity differences of the water, that the resultant force to drive the water is quite small. Therefore one should use pipes with large cross sectionall area (22 mm rather than 15mm), short pipe length and the pipe should be as straight as possible. (To reduce the resistance to flow)

 

With a controller system i feel that you could easily pump for too long as there is a thermal lag in measuring the temperature correctly. This in addition to the high flow rate of the pump will surely result in more mixing in the tank and consequently a negative effect on your stratification layer. 

 

These are just my thoughts.

 

Hi Carl,

I always thought this as well.

However, last winter I was running two thermosyphen geysers but ended up with lukewarm tanks at around 40 degrees.

Basically ran out of sunlight before the water could be heated more.

With a pumped system and decent controller, it will heat the water to say 70 degrees before starting the pump.

This way you might not have a full geyser of hot water, but at least enough for a decent shower.

 

I like the idea of Gustavo's air boxes. Should work well if you have some type of air circulation system.

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