Further Use of Solar Hot Water

dfbemt

I had solar system installed recently, link below to the product I installed. I am not an agent of any kind for this system or supplier. I just like what I got. I have also posted in a seperate thread on how much my gas bills have been since installation.

http://www.careyglasssolar.com/stevacuatedtube.php

My questions

1. Can I send this hot water to my gas boiler and make the boiler more efficient by heating already heated water?

2. Can this hot water be sent directly to my radiators (standard type)

3. Am I using it correctly? I have a 'knob' in my hot press (was there pre solar install) that reads 1 to 5. I take it this is a control for the heat but what should it be turned to and should it be at different settings for different times of the year?

Thanks in advance for help.

quentingargan

One of the advantages of tubes is that their output is less affected by air temperature than flatplates (tubes have their disadvantages as well by the way - I work with both and they all have plusses and minuses). So using the tubes in winter to heat water to 40 to 60 degrees is quite efficient. Flatplates fall off at these temperatures in winter and so there would be some argument for using them to bring water up very slightly and use the heat available as you describe.

Some people with large systems have used them to pre-heat water going to boilers etc., but the systems are expensive, and in our climate generally not worthwhile. To get a meaningful contribution to space heating, you would neede a huge array of tubes, and then you would have a lot of surplus heat to dump during the summer. These systems evolved in countries that have a lot more winter sunshine than we do.

The system of feeding the boiler which you describe may have problems as, depending on your system and where you live, the panel may need anti-freeze, whereas your heating system doesn't.

Your system is making a contribution to the hot water all year around by pre-heating the water in the bottom of your cylinder so that the gas has less work to do. Often in winter the solar will have heated this to about 40 degrees, which more than halves the amount of energy required from your gas.

I hope your system incorporates a heat dump by the way. This would be a dedicated radiator somewhere so that when the cylinder is up to temperature, instead of leaving the panel boil (which shortens the life of the system and degrades anti-freeze) it can be circulated through a radiator either in the loft, or in the bathroom. This is the only bit of space heating that most systems can usefully use. If you have a bathroom or shower on the north side of the house, it may reduce condensation during the time when the heating is off.

I haven't a clue what that knob is...

ruffmut

The knob in the hot press. Is it on a valve. If so its probally a anti scald valve. This allows you to mix cold water into your hot water pipe to help prevent hot water scalding you.

quentingargan

By the way, one of my problems with the system you have is that they rely on reflectors to increase the solar radiation on the tubes. Only time will tell, but I have concerns about how long the reflectors will be effective after a few damp Irish winters. The area behind the tubes doesn't really get washed by the rain, and moss, leaf mould etc. is endemic, even when there are no trees in the immediate area.

The other issue is that reflectors hugely increase the wind load. Tubes are always mounted on-roof rather than roof-integrated, but this isn't a problem because the wind blows through the tubes. Reflectors are a different matter. They will behave like a flatplate which has been surface mounted and gets buffeted, pushed and pulled quite a bit in stormy weather.

For those two reasons, I generally prefer tubes which do not rely on reflectors. I say all this in a generic sense - there are hundreds of suppliers of these besides ourselves, and there are also quite a few suppliers of the reflector system.

dfbemt

This system works well for me but I'm worried now about my roof on a windy night !!!

Seriously, thanks for info. I'll be looking for build up behind tubes. Can I clean this easily (no problem getting up on roof) or do I rely on rain?

quentingargan

dfbemt wrote: »

This system works well for me but I'm worried now about my roof on a windy night !!!

Seriously, thanks for info. I'll be looking for build up behind tubes. Can I clean this easily (no problem getting up on roof) or do I rely on rain?

If you have easy access to roof, that changes matters - They should generally be cleaned by rain. Maybe I am wrong on this and in five years time they'll still be nice and shiney and we'll all be selling vacuum tubes with reflectors! Keep us posted.

Also, the systems usually have appropriate mountings - my concerns would be on very exposed sites. I live in West Cork...

Q