wood fired hotwater

Straw bale, adobe - heck, even car tires can be used to construct a solid, earth friendly, energy efficient house! Share your alternative building experiences and ask for advice here

wood fired hotwater

Postby Trog » Mon Jun 06, 2011 8:32 pm

I am just in the process of connecting my second hand Franco Belge combustion stove to a Wilson heat exchange hot water cylinder, the stove used to run several radiators via a circulation pump. I am not using the radiators or pump now and anticipate the boiler circuit to work via thermosyphon. I am wondering if the boiler circuit should have a pressure relief or expansion valve?
Trog
Solar Supporter
Solar Supporter
 
Posts: 4
Joined: Mon Jun 06, 2011 8:13 pm

Re: wood fired hotwater

Postby lantern » Tue Jun 07, 2011 8:22 am

It should be "Open vented"
ie. if the water boils it must be able to escape and not build up pressure.
User avatar
lantern
Solar Crusader
Solar Crusader
 
Posts: 185
Joined: Thu Sep 24, 2009 11:33 am

Re: wood fired hotwater

Postby Tracker » Tue Jun 07, 2011 8:56 am

lantern wrote:It should be "Open vented"

I would go along with that.. One would like to be certain that a pressure valve could not FAIL and thus create a very dangerous situation.
Gordon is well versed in "Wet-Backs" -- What does your system use for safety, Gordon..?

The one curiosity is why you are dispensing with the heaters.. I would have thought they would have been Win-Win in the energy stakes.
..
.
Tracker
Solar Crusader
Solar Crusader
 
Posts: 5067
Joined: Wed Sep 23, 2009 5:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Re: wood fired hotwater

Postby Trog » Tue Jun 07, 2011 9:17 am

I do intend to use the radiators when i build my house, at the moment I have the stove in my 'temporary' accomodation (3 rooms) so no need although this is subject to change as the cold weather bites. The system ran a glycol solution in the boiler/radiator circuit when i purchased it, i dismantled the system (2 years ago) and have no recollection of it having a relief valve or of it being open vented. The feeder and return pipes from boiler to tank were sealed 1" pipes? The hot water supply is open vented to a copper header tank on the side of the main tank.
Trog
Solar Supporter
Solar Supporter
 
Posts: 4
Joined: Mon Jun 06, 2011 8:13 pm

Re: wood fired hotwater

Postby Gordon-Loomberah » Tue Jun 07, 2011 11:20 am

Yes, definitely open vented, ie zero excess pressure due to hot water expansion/steam. Wet backs are not designed to handle any pressure (beyond a few kPa due to the header tank), and in my case, nor are the water filled evacuated tubes, so the 250l tank is vented to the atmosphere.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5410
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: wood fired hotwater

Postby kesa32 » Tue Jun 07, 2011 6:21 pm

Hi Gordon , could you please explain how your system is set up ? l've been toying with the idea of incorperating our wood heatiing into our AAE ET system later on when this heater dies ( now 16 yrs old , but still going strong )
The solar does an ok job in winter ( Ballarat )it still needs a night boost , but with 3 women in the house its always going to be a battle :D
kesa32
Solar Fanatic
Solar Fanatic
 
Posts: 25
Joined: Sat May 21, 2011 10:42 am

Re: wood fired hotwater

Postby Trog » Tue Jun 07, 2011 7:26 pm

Hi Gordon, yes you are correct. I had another look today with a different attitude/prospective and indeed it is vented. Thanks for the info ;)
Regards Ross
Trog
Solar Supporter
Solar Supporter
 
Posts: 4
Joined: Mon Jun 06, 2011 8:13 pm

Re: wood fired hotwater

Postby Gordon-Loomberah » Wed Jun 08, 2011 9:37 am

kesa32 wrote:Hi Gordon , could you please explain how your system is set up ?


78 tube hydronics array on the left, with 250l tank, and a 1000l tank behind it out of view, and 30tube 250l hot water on the right, gravity fed from the 5000l tank you can see up the slope, proving 250kPa pressure at the house. You can see the thermosyphoning stepped hot, and angled down to the left return, pipes in between arrays on the hydronics system.

solar-hydronics-HW array-GJG.jpg
click to enlarge


The hydronics and solar are connected under the house via a heat exchanger, so that I can extract some of the hydronics heat into the hot water for periods when there is large demand (17 showers in a bit over a day is the biggest demand it's met to date), or when the hot water isn't hot enough due to cloudy weather (assuming I haven't used it all for house heating!).
I have a yet to be installed Everhot Deluxe wet back stove, which will also be feeding the hydronics system, which is vented at the fill tank you can see on top of the tank. I'll be using a high temperature water pump for that circuit (the same as the one for heating the house), as its not possible to set up the pipes from the stove to the tank in a suitable arrangement for thermosyphoning.
I have 25kg of (roundtable certified sustainably produced) palm wax that I intend to incorporate into the hydronics or hot water system as added heat storage, utilising the large latent heat of fusion of wax (mp ~62C). This may well end up in a ~100-200l tank at the back of the house, with the hot side of some sort of refrigeration device (ie a heat pump, but not a commercial one which are way too expensive) incorporated to add heat to it when required/as an energy dump.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5410
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: wood fired hotwater

Postby kesa32 » Wed Jun 08, 2011 1:41 pm

Thats a good set you have going there Gordon, the hilll is ideal , l presume your standing near the house for taking that photo ? also how are you pumpimg to the tank further up the hill , solar pump / windmill ?

Cheers Ken
kesa32
Solar Fanatic
Solar Fanatic
 
Posts: 25
Joined: Sat May 21, 2011 10:42 am

Re: wood fired hotwater

Postby Gordon-Loomberah » Wed Jun 08, 2011 1:58 pm

I was standing in the laundry doorway.

Venturing off-topic a bit...
I use a mono positive displacement pump to lift the water up there, and there are 2 other larger tanks (24000l total) further up, at 85m head, which will (when I get the 200m of 63mm poly dragged into place- not a simple task on that slope!) be used for storing water for hydro power (and firefighting at the house if needed). The pump will lift to 120m head, and is run from my PV/wind system, and I operate it it with a relay driver to start it only on days when there is a decent amount of charging, with a pressure switch cut-off. An 800W AC motor drives the pump... DC would have been nice, but the cost was prohibitive for me.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5410
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Next

Return to Alternative Building

Who is online

Users browsing this forum: No registered users and 6 guests

new solar power specials