Author Topic: Wood burners and pumped plumbing systems  (Read 23350 times)

Declan

  • Joined Sep 2009
  • Rathfriland, Co.Down
Wood burners and pumped plumbing systems
« on: August 15, 2011, 11:54:32 pm »
We have a pumped (unvented) watermains system with oil heating. I would like to change to a wood burner (log type) but have been told that as its a pumped system i cant have it. Something to do with the fact the the wood doesn't know when to stop burning and so it would "boil" the water in the system. As its unvented it would explode. Easier to think of it as its easy to turn off the oil supply when the temperature reaches a certain level- thereby preventing the whole thing getting too hot.

Any suggestions.



 

HappyHippy

  • Joined Jul 2012
  • Lesmahagow, Lanark
    • Yonderton Farm,
    • Facebook
Re: Wood burners and pumped plumbing systems
« Reply #1 on: August 16, 2011, 08:52:19 am »
I'm not a plumber or a heating engineer but there's bound to be a way round this  ;)
I have a multi fuel stove with back boiler (always worth going for multi, rather than just wood - higher output in terms of Kw) which runs our heating system and hot water, it our previous house we had a gravity run system which also had an oil boiler so we could run the system from oil or the stove.
I think you'll need a header tank for cold (and possibly a hot water cylinder too)
Here's a good site with a forum for asking questions to a registered plumber - he's helped me out in the past http://davidkearns.co.uk/
HTH
Karen  :wave:

benkt

  • Joined Apr 2010
  • Cambridgeshire
    • Hempsals Community Farm
Re: Wood burners and pumped plumbing systems
« Reply #2 on: August 16, 2011, 10:37:45 am »
We have a pumped but open system running our central heating (and hot water) from a Wamsler range/boiler.

Legally, you need to have at least one radiator directly attached to the wood burner that is always on (un-pumped) and so can always dump excess heat - we have the towel rail in our upstairs bathroom plumbed in for this job.
The next safety thing, is that the central heating pump comes on automatically once the main water store cylinder reaches a certain temperature ~90 degrees for ours. This obviously won't work in a power outage, so the final safety is a pipe that leads outside the house and can vent steam if the temperature reaches the next point ~95 degrees, I think. The cylinder is then topped up with cold water from the small header tank in the loft if this happens and it brings the temperature down pretty rapidly.

Moving from oil to wood, you're going to want a thermal store (basically a large hot water tank - the bigger the better) anyway and should be able to move to an open system when that is done. (You want the heat store so that you have hot water and heating in the morning without lighting a fire).
I believe you can connect an unvented cylinder to the output of the thermal store, so the wood burner side is vented and the oil-fired side is unvented but I've not looked into that setup much.

Bright Raven

  • Joined May 2010
  • North Shropshire
Re: Wood burners and pumped plumbing systems
« Reply #3 on: August 27, 2011, 07:07:02 pm »
I have oil, solar for water and a Yeoman wood burning stove with a back boiler. The system is gravity fed and goes through a piece of kit called a Dunsley heat exhanger. I have one radiator in the hall that works as a heat leak and a good big header tank. I recently looked at linking up a Wamsler solid fuel stove to the system and was told I would need to have a digital control box to cope with all the variations. My arguement at the time was that I am not daft enough to use the oil fired system at the same time as the solid fuel system but it didn't wash with the engineer who frankly seemed to think I was a bit mad. "I'll just run a bath if it starts banging" didn't impress him. I am now looking at Everhot stove just to provide background heat to my kitchen and do the cooking. It is less of a faff because it plugs into the wall and there is no need to put in a flue, or a solid floor or a digital control box. :)
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Fergie

  • Joined Oct 2009
Re: Wood burners and pumped plumbing systems
« Reply #4 on: August 27, 2011, 08:43:28 pm »
We have a 30kw log burning boiler (Bosky) which is on a vented gravity hot water & pumped radiator system.  We also have an oil boiler in the return, just before the Bosky.  A simple control system of pipe thermostats prevents the oil switching on if the water is already hot, but in extremely cold weather both boilers can work together for a fast warm up.  We've never had overheated water - the oil boiler will just switch off once the required temperature has been reached.

95% of the time, we never use the oil boiler (too expensive) but it's useful to have as a back up.  The only downside of the plumbing arrangement is that it's very inefficient to heat a hot water tank using just oil this way - the oil boiler has to bring the wood stove up to temperature first, so it acts as a radiator.  However, the converse is true - most evenings we light a few logs in the Bosky which is enough to get a tank full of hot water for the next 24 hours, at virtually no cost.

I did assist a friend to plumb in a similar Bosky into a sealed gas system, using a heat exchanger, so I know that can be done too.  On their system, a vented solid fuel system has a large water to water heat exchanger which transfers heat into the sealed system, thus reducing their gas consumption when the stove is lit.

We've been running almost totally on wood to heat 14 radiators for over 20 years now, with no problems apart from replacing the first Bosky when it reached about 25 years old (it was second hand when we bought it - the replacement was new).

Right now, we're busy splitting logs for next winter, using a tractor mounted splitter.  About 12 tons a year is normal.

Find a sympathetic plumber or heating engineer - a combined system is not too difficult, if well planned.

John

northfifeduckling

  • Joined Jan 2009
  • Fife
    • North Fife Blog
Re: Wood burners and pumped plumbing systems
« Reply #5 on: August 29, 2011, 07:39:20 pm »
we run both alongside each other. oil is good for heating the water real quick in the summer. Wood/coal burner can do most of the heating in the winter BUT we have to switch on the pump and the oil for about 10 minutes until the water circulates. Does it make sense? It's not bad. We have it this way because we switched from coal/wood only to oil but wanted to keep the burner....

WilliamLaurence

  • Joined May 2012
Re: Wood burners and pumped plumbing systems..Wood Stoves
« Reply #6 on: May 31, 2012, 08:14:09 pm »
I bought one of these from ChimneyHeaters.com . I installed and it works fine. Heats my 2000 square foot house. I have the pump connected to a UPS but I am not sure how long the pump will run if the electric goes out. I had it installed all winter and did not have to turn on my Electric heat once which saved me about 200 euro a month here in Romania.

The Electric is not stable here so I had to rush to take out the fire a couple of times because the water pump had stopped and the pressure valves were going off. The UPS will solve that but I don't know how long a UPS will keep my central pump going.  I will attach a pic of what chimney heaters are in case you are not familiar with them. The pump is a Grundfos and has three speeds.


FiB

  • Joined Sep 2011
  • Bala, North Wales
    • Outdoor Champions
    • Facebook
Re: Wood burners and pumped plumbing systems
« Reply #7 on: May 31, 2012, 09:23:19 pm »
We were told the same (especially as we are all on one level so couldnt have an upstairs radiator as a heat sink.  We finally foung a hetas engineer that would do it and it works fine.  He put in an expansion tank in the loft with an overflow pipe that would spurt outside (highly heath robinson, but conforms to regs.  In reality in the event of a powercut I now realise we could just run a big bath to dump heat (as well as shutting fire down and removing fuel), so I really dont know what the fuss is about.  Hell of a job to find someone to do it though and I'm sure we paid too much but dont regret it.  We've kept the LPG connected as back up (against our wishes!!), and in all honesty have enjoyed it for an hour in the mornings through the winter. Good luck!

robbiegrant

  • Joined Aug 2012
  • Cupar. North East Fife
  • The Mighty Kroshka!
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Re: Wood burners and pumped plumbing systems
« Reply #8 on: October 09, 2012, 11:25:35 am »

I have a multi fuel stove with back boiler (always worth going for multi, rather than just wood - higher output in terms of Kw) 

They are generally built better and last longer too.
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robbiegrant

  • Joined Aug 2012
  • Cupar. North East Fife
  • The Mighty Kroshka!
    • Exclusive Luxury Holiday Villa for Rent in Goa
Re: Wood burners and pumped plumbing systems
« Reply #9 on: October 09, 2012, 12:12:54 pm »
I have oil, solar for water and a Yeoman wood burning stove with a back boiler. The system is gravity fed and goes through a piece of kit called a Dunsley heat exhanger. I have one radiator in the hall that works as a heat leak and a good big header tank. I recently looked at linking up a Wamsler solid fuel stove to the system and was told I would need to have a digital control box to cope with all the variations. My arguement at the time was that I am not daft enough to use the oil fired system at the same time as the solid fuel system but it didn't wash with the engineer who frankly seemed to think I was a bit mad. "I'll just run a bath if it starts banging" didn't impress him. I am now looking at Everhot stove just to provide background heat to my kitchen and do the cooking. It is less of a faff because it plugs into the wall and there is no need to put in a flue, or a solid floor or a digital control box. :)


Greetings. Yes the dunsley valve works but it has limitations and can be a pain if it is not set up properly. These valves been superseded with  more advanced systems that are much more flexable and allow a number of different connections... Ground source/combi boiler/oil/ multifuel  unvented and pressurised systems working together. http://www.h2panel.co.uk/ the gentleman who has invented these systems is very approachable and has a wealth of experience with hooking different types of systems together.
Cupar weather http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=cupar
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Escape to paradise - http://www.vaastuvillagoa.com

It might look like I'm doing nothing, but at the cellular level I'm actually quite busy ;)

MAK

  • Joined Nov 2011
  • Middle ish of France
    • Cadeaux de La forge
Re: Wood burners and pumped plumbing systems
« Reply #10 on: October 09, 2012, 06:32:42 pm »
Just log burning stobe here - we too have an expansion tank in our loft. It is actually our bedroom but quite large. We have 3 radiators up there in the loft so the expansion tank has to be higher than them. Our log burner has a thermostat that will close a rear air vent if it gets too hot but of course if there is a mass of fuel to burn with the front upfradt ( used to stop soot on glass of stobe) then the fuel will still burn and the water temperature of circulating water will continue to rise.
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chrismahon

  • Joined Dec 2011
  • Gascony, France
Re: Wood burners and pumped plumbing systems
« Reply #11 on: November 05, 2012, 06:20:02 am »
Our neighbours have just replaced their oil boiler with a German made wood burner. It takes logs and is unvented. Cost €40,000 with a government subsidy of €3000 to get back when completed. I haven't taken much interest, even as a plumber, as it is an industrial unit really and would never be a heating solution for me. Logs have to be the correct size, that's length and diameter, to suit the feed system. It has two water cylinders and a diverter system, like a modern gas combi-boiler. The expansion vessel is massive! I can see it being a load of complicated trouble! The fuel may be free here, but the servicing and maintenance costs?

FiB

  • Joined Sep 2011
  • Bala, North Wales
    • Outdoor Champions
    • Facebook
Re: Wood burners and pumped plumbing systems
« Reply #12 on: November 05, 2012, 08:35:32 am »
£40K euros????   Blimy Im with you chris ....Bonkers - why would you?  limited  chance of paypack in your lifetime even with free fuel.  I though our system was marginal at £7K!!!  Just a note to this thread - our single level system (with miniscule overflow tank in loft) still working well one year on, a serious power cut mid burn will be the test mind you (but I still thing running a bath will be sufficient to deal with the situation.)

MAK

  • Joined Nov 2011
  • Middle ish of France
    • Cadeaux de La forge
Re: Wood burners and pumped plumbing systems
« Reply #13 on: November 06, 2012, 08:47:53 pm »
What 40 k for a heating system! My house did not cost much more - and we got a hanger full of seasoned wood left for us.
I wonder how many years I could have electric blankets, towel rails and the gas cooker blasting out heat for if I had 40k to spend. I really must be a peasant to be happy burning a few logs whilst wearing a hat when we have the bitter cold. If I get too cold I go down into the cellar as it is warmer there than in my workshop.
www.cadeauxdelaforge.fr
Gifts and crafts made by us.

robbiegrant

  • Joined Aug 2012
  • Cupar. North East Fife
  • The Mighty Kroshka!
    • Exclusive Luxury Holiday Villa for Rent in Goa
Re: Wood burners and pumped plumbing systems
« Reply #14 on: November 09, 2012, 02:08:59 pm »
our 10.5kwatt wood burner is so fierce we can only light tiny fires in it or we bake... and thats fully closed down with the winows open!  We probably need to decrease the size of the firebox with firebricks or summat.

I blame all that bloody insulation  :innocent:
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Escape to paradise - http://www.vaastuvillagoa.com

It might look like I'm doing nothing, but at the cellular level I'm actually quite busy ;)

 

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