Solar Heating idea

css

I've got a basic concept of a system to decrease the amount of heating required that i'd like opinions on.

The basic system would involve using Solar evacuated tubes to heat the water being used by an oil/wood chip burner. My theory being that while the solar might not always heat the water up much all the time. It should heat the water up to some degree. So instead of say heating water from 10C to 36C it might increase the base temperature of the water to say 20C. Which would result in less fuel being expended to heat your house.

My question is this: Is this type of system workable and possible?

I haven't done any figures regarding payback, etc. But in theory you should reduce your ongoing heating bill with the once off expense of the tube system. What do you think?

Capt'n Midnight

It's done a lot on the continent.

Perhaps you could use thermostats so that water would only flow through the pipes when the temperature was above a certain amount - or use solar powered solenoid valves/pumps

Just wondering what effect would insulating your cold water tank in the attic, since the water for heating comes from there.

JamesM

Capt'n Midnight wrote:

Just wondering what effect would insulating your cold water tank in the attic, since the water for heating comes from there.

The water for the heating system is in the system all the time - it is just topped up from the header tank in the attic.
The water which comes out the hot taps comes from the cold water tank in the attic. I think that that's the water which can be pre-heated by solar.
CSS: you say "to heat the water being used by an oil/wood chip burner" That water is all around the house - in the boiler, radiators etc. Very difficult to get at to pre-heat. When would you pre-heat it ? - Presumably day-time. Where would you store it, when heated ? Usually you want heat in the evening - no solar heating at that time.
You would be better pre-heating the water between the cold tank in the attic and the hot taps. Just my thoughts.
Jim.

css

Interesting. I haven't really checked out the possibilities yet as I said.

Ok from a brief look I've found a possible answer to my theory! Check out: http://www.navitron.org.uk/solar_cylinder.htm

So all you'd really need to do would be to hook this up to both your solar input and the main heating circuit, before it enters the boiler, and it should do what I was thinking, (in theory!)..

Does anyone know if underfloor heating systems have a reservoir of water, or is all the water stored in the pipes and heated as it flows??

JamesM

css wrote:

Interesting. I haven't really checked out the possibilities yet as I said.

Ok from a brief look I've found a possible answer to my theory! Check out: http://www.navitron.org.uk/solar_cylinder.htm

So all you'd really need to do would be to hook this up to both your solar input and the main heating circuit, before it enters the boiler, and it should do what I was thinking, (in theory!)..

Does anyone know if underfloor heating systems have a reservoir of water, or is all the water stored in the pipes and heated as it flows??

That would work alright. The solar panel would work through the lower coil - the boiler would heat the upper one. If the cylinder is cold the solar heat will rise and heat the upper part of the cylinder. This will then be topped up by running the boiler when hotter water is needed.
I don't think that there would be a resevoir for underfloor heating - not when using a boiler. Maybe geothermal uses some kind of resevoir.
Jim.

css

I'm going to try and find out if there is JamesM, as I think this idea has possibilties..

Uuuh Patsy

css wrote:

I'm going to try and find out if there is JamesM, as I think this idea has possibilties..

Just wondering if anything ever came of this discussion

css

Nothing I'm afraid. But I did get some more objective information on the whole solar heating idea. And the payback period does not make it economical at all. I'm now looking at using a multi-fuel stove, paired to a wood chip burner. So the stove will pre-heat the water when it is lit, and the boiler will further heat the water if it is needed, or heat it if required.

rooferPete

Hi css,

I think what you are looking for is a buffer tank which acts a central heat store, all the water in the tank is heated by either the Solar and any other boiler you have installed.

Your theory is used more in the US that I know of, where large wood burning furnaces are allowed to burn slowly for days, the heat from the solar is added using coils similar to the type we are used to.

The idea being that the building is served by the hot water which is at the top of the tank, some install cylinders similar to our copper cylinders to use the water for showers etc.

The examples I have seen have very large tanks that are well insulated, I expect it would take some getting used to here although the theory is similar to replacing heat lost in the home,except they do it by running the boilers / furnaces to burn slowly topping up the heat used.

There have been complaints and the systems are either banned or closely monitored in some States, the system is not the problem, it's the way that some people fill large boilers with fairly damp wood causing smoke to hang in the air for endless hours that can in some cases amount to days.

All this time the unlucky neighbours and sometimes even road users find themselves in dense smog.

The problem can be sorted out by using dry timber, thermostats and flue dampers that are controlled by the temperature of the water in the buffer tank.

I think aquatech have a system that works in a similar way where you can add your solar link to the bottom of the tank, take care when looking for them, the prices are not for the faint hearted

css

Many thanks for the input RooferPete. I knew I couldn't be such a great inventor!!