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

Re: wood fired hotwater

Postby kesa32 » Wed Jun 08, 2011 5:45 pm

Ok , so your pumping from a lower supply tank l take it , l'd love to get pressure like that from gravity feed.......unfortunately our neighbour own the hill and it's still not steep enough anyway ;)
We run a constant pressure pump ( grunfos...been a great unit )and l'm just about to add a 100 L pressure tank to help stop short cycling and also give us a little water to use when the power goes out
We're getting a 5kw PV system installed next week , pity there was'nt a way to use when the grid goes down , anyway if the pressure tank works out ok , l might add another for some more capacity ( still much rather your water setup though :) )
kesa32
Solar Fanatic
Solar Fanatic
 
Posts: 25
Joined: Sat May 21, 2011 10:42 am

Re: wood fired hotwater

Postby Trog » Wed Jul 06, 2011 10:40 pm

Hi, I have got the stove running with 2 water radiators operating well with thermo syphoning (no pump).
I have just completed the hot water supply pipes to kitchen and bathroom but with supply turned on I have no hot water, other than from a post manuacture midmount hot water outlet to supply shower?? . I have a Wilson 250L ceiling low pressure tank and was under the impression the cold supply was circulated via a coil immersed in the hot water from the boiler/stove? But after running a hose down the cold intake pipe, instead of flowing out the "coil outlet" it overflowed back into the header tank, the same place the hot water from the boiler vents??
Does anyone have a schematic of this tank or advice please?
Trog
Solar Supporter
Solar Supporter
 
Posts: 4
Joined: Mon Jun 06, 2011 8:13 pm

Re: wood fired hotwater

Postby Gordon-Loomberah » Mon Mar 12, 2012 8:59 am

Trog wrote:Does anyone have a schematic of this tank or advice please?


In case you are still watching this thread, the Wilsonhotwater website has a schematic here:
http://www.wilsonhotwater.com.au/domest ... gmodel.pdf
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: 5444
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: wood fired hotwater

Postby sandystone » Tue Apr 09, 2013 10:55 am

Hi - some feedback please...
I am going to install a wood heater shortly (a Kent 1000) for space heating . which will certainly look after the space heating. However, for the bathroom, which is on the south side and has a tiled, suspended timber floor, we would like a heated floor, and are considering hydronics, fed from a heat exchanger mounted on the flue.
Heating season - around 3 months
My thoughts are currently:
-Install a flue heater such as: wrap a coil of copper around the flue, OR this: http://www.scfab.com.au/index.php?page= ... austenitic. (about $1100)
+run the hot water to an an insulated tank with vent
+run some plastic hydronic piping, (or copper?) around under the bathroom floor and insulate underneath
+the floor the heater is on is the same level as the bathroom, so will need a circulating pump
My questions are:
-How effective is hydronics under a suspended floor, if the pipes don't make excellent contact (like in a slab) ?
-Would the flue get clogged frequently because it is being cooled by water
- has anyone else tried something similar?
- how effective/ cost effective is this kind of system?
Any other ideas?
Thanks
sandystone
Solar Supporter
Solar Supporter
 
Posts: 23
Joined: Tue Apr 12, 2011 11:28 am

Re: wood fired hotwater

Postby Tracker » Tue Apr 09, 2013 11:13 am

.
Silly question... It sounds like the bathroom has YET to be built..

So, why cant you insulate under the floor....
The use a leveling slurry over the pipes, and then tile over that..
That way you get a medium to conduct the heat where you need it..

Sure it will SIGNIFICANTLY raise the floor, but does that matter..
You can lower it to start with.. :idea:
..
.
Tracker
Solar Crusader
Solar Crusader
 
Posts: 5068
Joined: Wed Sep 23, 2009 5:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Re: wood fired hotwater

Postby sandystone » Tue Apr 09, 2013 11:33 am

Bathroom flooring and tiles are existing (as it says) and newish about 8 yrs ago.
sandystone
Solar Supporter
Solar Supporter
 
Posts: 23
Joined: Tue Apr 12, 2011 11:28 am

Re: wood fired hotwater

Postby Cherokee Solar » Tue Apr 09, 2013 8:29 pm

Hi sandystone,

I use the Thermalux Gourmet wood heater here with an 8kW wet back:

http://www.thefireplace.com.au/wood_fired_cookers.html

The house here is also built on stumps with a timber floor (Sydney Blue Gum).

sandystone wrote:+run some plastic hydronic piping, (or copper?) around under the bathroom floor and insulate underneath


I doubt whether this will work. The reason for this opinion is that most of the heat will be lost in the sub floor space to the air. The sub floor space needs to be ventilated - even in a bushfire resistant house - and as such it will always be colder than the house.

I've suspended R3.5 batts directly under the timber floor and the timber is never cold (or hot) regardless of the outside temperature.

The wet back on the wood stove uses an open vented tank (400L) in the roof which you can pump water around to various radiators in the house. It is a very effective system. The tank also has a couple of solar hot water panels connected to it for summer heating as well. An 18m copper coil sits in the tank and the house hot water comes from this system too.

sandystone wrote:+run the hot water to an an insulated tank with vent


Yeah, this will work well. The tank has to be mounted more or less above the wood heater as the hot travels up and down via convection. You cannot put a pump in such a system. Well, it won't be good if you do. ;)

sandystone wrote:+the floor the heater is on is the same level as the bathroom, so will need a circulating pump


The circulating pump is connected to the hot water tank - not the wood heater - and they are very energy efficient. You can have as many or as few radiators as you need. The more radiators though, the bigger the wet back on your wood heater will need to be. It also takes a few hours of the wood heater going full bore to get the heat into the tank. It is not a quick exercise.

sandystone wrote:if the pipes don't make excellent contact (like in a slab)


You'd never be able to heat a slab with a wood heater as the thermal mass is too much. The wood box would have to be running more or less continuously all winter. It is akin to trying to catch water in a sieve. As an experiment, go outside and sit on the ground sometime in August and see how long you can sit there without freezing. A house on a slab has to do the same thing. An insulated and suspended floor performs much better as it doesn't have to heat the surrounding ground as well.

sandystone wrote:Would the flue get clogged frequently because it is being cooled by water


Running a wet back (or the sort of system you are talking about) requires the wood heater to be run at almost full bore for a couple of hours at least. The flue gets clogged most often because people are burning unseasoned or wet timber. Either way the timber is not burning efficiently. This will impact the flue far more than the wet back. Blocked flues can be a serious fire hazard.

By the way seasoned means cutting the timber and letting it sit for more than 12 months - possibly even 24 months. I've never had to clean the flue here and it looks pristine.

My house is at the back of Mount Macedon at elevation in central Victoria and it gets really cold outside here over winter but the house is always pleasant in both summer and winter regardless of what is going on outside. If you live in a cold area, you really need to build your house as if it was a thermos / esky. :)

A lot of people go for thermal mass here and find that they never have enough energy to heat the houses and the floors and walls all radiate cold air. Seriously, I've witnessed unpleasant arguments between couples over this issue.

If you have a chance to exchange your wood heater for one with a wet back, I'd seriously recommend this. Also a wood fired oven is to kill for. Fresh bread, cakes, biscuits, stews etc. Yummo! :D
Off grid solar + hot water. Heavily insulated + owner built flamezone house BAL-FZ. 300 mixed fruit trees + herbs + flowers + vegetables. Bees + heritage chickens. High up in the mountains north of Melbourne. http://ferngladefarm.blogspot.com.au/
Cherokee Solar
Solar Crusader
Solar Crusader
 
Posts: 823
Joined: Tue Jan 05, 2010 9:11 pm
Location: Cherokee, Victoria

Re: wood fired hotwater

Postby sandystone » Tue Apr 09, 2013 9:28 pm

Thanks for your chunky insights Cherokee, As the climate here on the NSW Central Coast is mild, never getting below zero, and rarely below 5, the issues are not so severe as what you face.

Also, We will only need to heat the bathroom floor, because of bare feet and the need to reduce mould issues on the tiles. (it is quite humid here too) and the good air circulation in the rest of the house doesn't happen in the bathroom.

Not really clear on your underfloor insulation explanation, as I was considering a double sided RF foil and then some blanket under with R3 blanket. and it is only on the bathroom where I would need such detail. I would have thought the only direction for heat would have been up?

Too late for a change of heater, and it was one of the few (aesthetic) designs which worked in our house. The only option is a flue heater. The stated output of the heater is 14kW, and that is heaps for our house and climate type.

Scenario- Fire lit when get home from school/ work, 4-530 pm. Hot water still in tank from previous evening heats floor for those pm showers, and water being heated to recharge. Perhaps a timer on the pump could pre-heat the floor, depending on how long the thin floor takes to heat up. (18 mm cement sheeting and tiles)
Then if showers in the morning, then another timer period.....
yea it is complicated, hmm
sandystone
Solar Supporter
Solar Supporter
 
Posts: 23
Joined: Tue Apr 12, 2011 11:28 am

Re: wood fired hotwater

Postby Cherokee Solar » Wed Apr 10, 2013 9:52 am

Thanks. :D

sandystone wrote:Also, We will only need to heat the bathroom floor, because of bare feet and the need to reduce mould issues on the tiles. (it is quite humid here too) and the good air circulation in the rest of the house doesn't happen in the bathroom.


If you're dead keen on the underfloor heating in the bathroom, how about this:

I'm assuming your house is built on stumps with timber bearers and joists (make sure they're treated because of the humid environment). Place a waterproof membrane over the timber joists (ie: plastic) and then install 15mm fibro cement tongue and groove sheet flooring.

http://scyon.com.au/secura_exterior.html

Note that it is an external product used in very wet areas and will go the distance. Most other fibro products will transmit water to the timber sub floor and it will rot out over the years (and fail).

You could probably then put hydronic heating pipes in a slurry - like they do in the UK - and then tile over the top or just polish the concrete.

sandystone wrote:Not really clear on your underfloor insulation explanation, as I was considering a double sided RF foil and then some blanket under with R3 blanket.


Yeah, not sure I'd put batts directly under the timber floor in an area like Northern NSW where humidity is high.

sandystone wrote:Too late for a change of heater


Oh well. Wood heaters can perform so many functions and the transfer of heat from a coil around the flue is much lower than a wet back that sits inside the fire box. 14kW is pretty good. Most people put in wood heaters that are too large and they end up using trailer loads of wood. Very inefficient. A small well designed wood heater in a small house will work really well. I barely use the hydronic radiators. In fact two of them have not ever been used and I was thinking of removing them and selling them.

sandystone wrote:yea it is complicated, hmm


Too true. Supplying your own of anything is much more complicated and time intensive than most people realise. Far easier to switch on your lights and not worry about where the energy came from. Wood heating is exactly the same and I have to plan years ahead for firewood (plenty of trees here). :D
Off grid solar + hot water. Heavily insulated + owner built flamezone house BAL-FZ. 300 mixed fruit trees + herbs + flowers + vegetables. Bees + heritage chickens. High up in the mountains north of Melbourne. http://ferngladefarm.blogspot.com.au/
Cherokee Solar
Solar Crusader
Solar Crusader
 
Posts: 823
Joined: Tue Jan 05, 2010 9:11 pm
Location: Cherokee, Victoria

Re: wood fired hotwater

Postby sandystone » Wed Apr 10, 2013 10:17 am

As I mentioned, the tiled floor is already installed, so I am limited to underfloor installation, and I found out that to assist with heat distribution under the existing cement sheeting, to affix some aluminium sheeting to transfer heat from the piping to the floor, which will minimise/ eliminate the risk of expansion cracking on the tiled floor.

(ps, I am looking forward to putting the camp oven in the fire for some roast vegies! yum)

BTW, the Kent heater is rated at 74% efficiency...which seems reasonable for au heaters, though some OS units were in the 90 % range..... but dry wood and good insulation and pelmeted curtains minimises the hassle of excessive labour gathering wood.
sandystone
Solar Supporter
Solar Supporter
 
Posts: 23
Joined: Tue Apr 12, 2011 11:28 am

PreviousNext

Return to Alternative Building

Who is online

Users browsing this forum: No registered users and 1 guest

new solar power specials