Greenhouse and house boiler

[marketfarmer]

We are expanding our Vermont based farm next year and are building a new house and greenhouse. The house will be pretty tight and well insulated. Using a calculator I came up with a ballpark load of 23000. I'm am not sold on any heating method yet in the house. My wife would prefer not having baseboard heating cause our house is on the smallish side already and any extra floor space taken up will reduce it further. The greenhouse which will be adjacent to the house will have a load between 110,000 and 175,000. I'm hoping to have a boiler to run both and was planning on it being in a shed that connect to both the house and the greenhouse. Any advice on what brands and setup would be really helpful. Thanks.

 

[leon]

You have a tiger by the end of the tail, and UGH you
have a lot of work to do to decide what type of fuel
you need as your green house addition is going to
require a lot of fuel if you are intent on running it
the year round.

You have to plan on making decision trees to do all your
investigating and asking a plumbing design specialist from
B+G or TACO to help you with your home heating needs.

Flat panel radiators with the square copper pipe eliminate
the need to have pipe under the door thresholds and it
paints well too and. They have been using it in Europe
for many years.

You need to use several decision trees for every aspect of
the heating project from design to finish to solve problems
before they start and save money.

 

[marketfarmer]

Thanks for the comment. With our farm expansion comes a lot of firewood from clearing for pasture reclaiming and junk wood clearing out in the woods So we will have more cord wood then we know what to do with. And my father in law and brother in law are both fallers by trade. So we are pretty set for fuel source.
The greenhouse is a part of our vegetable operation, right now we have a smaller one that we heat with a wood stove for starts in the spring. For the majority of the winter we will only be looking for night time temps around 36 which makes our load much lower then the max. And we will have a back up propane air heater for nights in late winter when our tomatoes starts will need at least 55F. That back up heater should drop us down to the 100,000 btu draw from the boiler. All we have ever had in our house is a wood stove and have little experience with a distribution system. That why I'm asking here first so I can figure out the right questions to ask a designer.

 

[maple1]

With a new small house like that, in that climate, I think I would consider a ductless mini-split heat pump for the house and maybe a wood furnace for inside the greenhouse. Could possibly also add a wood stove to the house to supplement.

An OWB is a big investment - not just up front now, but it will tie you in to keeping a fire burning pretty well 24/7 all winter for however many winters you have it. With a big appetite to boot. Have you done any cost estimations yet? Underground piping is between $10 & $20/foot, for starters.

And since you mentioned shed - an indoor boiler + storage in an outbuilding might be another possibility. I would likely do that ahead of an OWB - the outbuilding maybe being an extension or add-on to the greenhouse? Your overall site layout may play a part too.

 

[Easy Livin’ 3000]

You don't want an outdoor boiler. No one really does.

Indoor with storage would be my preference. You'll have enough wood for yourself, and to sell, with what you described. The greenhouse can come right off that if sized and plumbed correctly. Way more efficient and no trips outside to load.

Good luck with the radiators, if I were building from scratch, I'd use pex under floor. I'm still going to do that, to get these big radiators from eating up our floor space. Just need the runway.

You already know what the right way to go is. Just think it through.

 

[peakbagger]

I believe VT has effectively banned OWBs, check with VT air division.

There are options to not using baseboards. You can go with radiant heating in the floor, the walls or the ceiling. Radiant is also a good option for the greenhouse floor, just make sure its got a glycol in the loop. It comes down to how big is the greenhouse and its possible heating load versus the home. If its large greenhouse, you may be best served by a Garn. If its a smaller greenhouse, a gasifier boiler with storage is an option.

The big issue you have is this really is not a DIY project, you really need it designed and heating system designers with wood experience are rare. Might be worth giving the folks at woodboiler.com in Orford NH (who sell wood boilers), may know of a good designer. You have to be careful there are plenty of hacks without credentials that will design you a system "for free" to sell you equipment that they happen to sell.

John Siegenthaler did a course for New York State on integrating Biomass heating with hydronic systems. I haven't taken reviewed that course but I did a similar more advanced course he did and it was excellent. It may be available for free out there but here is link to one source https://www.heatspring.com/courses/...iciency-biomass-boilers-sponsored-by-nyserda/

 

[leon]

I stopped burning wood 3 years ago after 33 years of dealing with the mess and I had an indoor hand fed wood and coal boiler.
I am using a coal stoker boiler to heat my home in the winter and also provide my hot water.

You will not get to all the firewood before it begins to rot either so your going to lose a lot of it even with it being tarped.

Please begin your thinking with being 10-15 years older with regard to this as dealing with firewood is a very labor intensive long term issue.

Just so you understand this, a very, very, small propane fired steam boiler the size of a typewriter table will give you all the heat you need and provide you with hot water with a submerged coil in the steam chest.

You can use flat panel radiators for steam heat for your home with TRV's with small diameter refrigerant grade copper to feed each
flat panel radiator fed with steam and use a one pipe steam to hot air modine heater for your green house.

The other thing is that with the small diameter copper tubing heated flat panel or steam radiators with TRV's you can run high velocity air conditioning ducts without having to install ducting around larger steam pipes.

 

[pbvermont]

In building a house new, you would be remiss in putting in anything other than radiant floor heat. That decision is simple. It would be even better if you had a full basement and had your heating plant down there--a woodfired boiler with maximum heat storage tank. It would be problematic putting radiant tubing in the greenhouse soil if you were going to "work" that or use implements/machinery in it. So an air handler fed by radiant tubing would be best option.
Fuel management (drying, storage and handling) would be a big issue for you--i.e convenient space for it. Consider the "flow" of that material. A Garn boiler works well in farm settings with multiple bldgs. It is an "open" system and has its own issues. DO plan for power outages. Have proper and reliable alarm system for greenhouse.

 

[maple1]

I'm not so sure on the radiant floor heat being the simple decision, in new home construction. New construction can be made so efficient that not much heat is needed period, and ductless heat pumps can heat very economically and also give you some a/c in the summer if wanted.

Having said that - if still undecided and it's getting down to crunch time, it might not be a bad idea to sink some pipes in the concrete anyway (and insulate underneath - which should be done regardless) since it would be a small portion of the overall cost even if you end up not using them. Then your options are truly wider open for the future - you might even be able to heat your floor with an A-W heat pump with the way tech is evolving & improving.

I guess my bottom line advice would be to plan/design the new construction as if you would not be heating with wood - consider wood as secondary heat source. That will improve things for when the time comes that you don't want to burn every day or will be away for extended periods or even maybe consider selling. Or have an other half that isn't quite as enthusiastic about wood fires as you might be. It does get to be a chore day after day, month after month, year after year.

 

[peakbagger]

I'm not so sure on the radiant floor heat being the simple decision, in new home construction. New construction can be made so efficient that not much heat is needed period, and ductless heat pumps can heat very economically and also give you some a/c in the summer if wanted. I agree with this sentiment but greenhouses inherently tend to be energy hogs as the type of construction required to let in the sun during the day tends to be less efficient at keeping the heat in at night. Proper shading and locating high thermal masses where the sun can get to them helps a lot. I run a mini split in Northern NH and unfortunately they really aren't a primary heating source during very cold weather that happens on occasion especially when the relative humidity is high during a snow storm. Yes they do put out some heat down to -15 F but valleys in VT can see -30 F on rare occasions. This is probably rarer in Atlantic Canada. My personal point where I switch off the minisplit is when the temps dip under 10 deg F as the unit tends to be noisy during frequent defrost cycles.

Having said that - if still undecided and it's getting down to crunch time, it might not be a bad idea to sink some pipes in the concrete anyway (and insulate underneath - which should be done regardless) since it would be a small portion of the overall cost even if you end up not using them. Then your options are truly wider open for the future - you might even be able to heat your floor with an A-W heat pump with the way tech is evolving & improving. Definitely worth considering putting in tubing but realize that its best to design the tubing to the actual floorplan and use. Ideally you put the tubing where you need the heat and put far less where you don't. Radiant heat doesn't not work very well unless there is direct open space between the surface.

I guess my bottom line advice would be to plan/design the new construction as if you would not be heating with wood - consider wood as secondary heat source. That will improve things for when the time comes that you don't want to burn every day or will be away for extended periods or even maybe consider selling. Or have an other half that isn't quite as enthusiastic about wood fires as you might be. It does get to be a chore day after day, month after month, year after year.

The "peoples republic of VT" tends to look at wood burning as pretty much standard for a house. No natural gas in the ground to speak of unless in the developed areas of Burlington or along the new pipeline corridor between Burlington and Middlebury. The state has chronically underinvested in electrical infrastructure in the rural areas where people like to and can afford to build and utility resources are stretched so power outages tend to happen frequently and for extended durations. Many town roads and even a few state highways are dirt and some of the older ones are built to a low standard which means during mud season, oil and propane deliveries may not happen. Sure there are high end homes built for people who moved from the area "from away" but wood stoves at a minimum are pretty well expected by most buyers and well designed wood boilers with storage are appreciated.

I think Green Building Advisor is based out of VT http://www.greenbuildingadvisor.com/ might be worth getting a subscription.

 

[Chris Hoskin]

We are expanding our Vermont based farm next year and are building a new house and greenhouse. The house will be pretty tight and well insulated. Using a calculator I came up with a ballpark load of 23000. I'm am not sold on any heating method yet in the house. My wife would prefer not having baseboard heating cause our house is on the smallish side already and any extra floor space taken up will reduce it further. The greenhouse which will be adjacent to the house will have a load between 110,000 and 175,000. I'm hoping to have a boiler to run both and was planning on it being in a shed that connect to both the house and the greenhouse. Any advice on what brands and setup would be really helpful. Thanks.

Hi marketfarmer, I really like the idea of combining your wood boiler room with the greenhouse if that is practical. If you have the ability to include your thermal storage and some wood storage (1 cord?) in there too, that would be ideal. You have the unusual situation where you have a very small heating load for the house and a very large (periodic) load for the greenhouse. The way to deal with that is to put in a large wood boiler and very large thermal storage (1000+ gallons). That way you have a large enough wood boiler to heat the greenhouse AND enough thermal storage to accommodate the house only when you are not heating the greenhouse. Also a super convenient system in that, when you are not heating the greenhouse, you will only have to fire the wood boiler every day or two - and probably no more than once a week in the summer depending on how much domestic hot water you use (more often if you are using hot water to wash vegetables, etc.). You'll want high temp distribution to the greenhouse (Modine-type heater) and low temp to the house. I think a radiant floor system would be a great choice comfort-wise and space-wise. We've got some great dealers in VT who can look after all of this for you. Give me a call at Tarm Biomass or message me back and I'll be glad to put you in touch. Chris