Print

[Briansbotanicals]

I have a heatmor boiler that we have been using to heat several greenhouses for over 10 years. We have it pretty much over loaded heating 4 greenhouses with one unit. We currently do not have the funds or area to add an new unit. So I have been trying to find a way to make this one more efficient. My first idea was to use copper tubing wrapped around a 4 foot stove pipe at the top of the boiler and have it pumped back into the system. Essentially catching some of the heat off the stove pipe which maybe enough to heat part of or most of one of the smaller greenhouses. I have not priced the over all expense and time it will take to make the copper tubing contraption. After searching the internet I found something along the same lines called the Aquastack apparently a device that would reclaim some lost heat out of the stove pipe. From what I have seen no one has responded in older post that has actually used the unit described? If so does it work and does it work well enough? Would I be better off building my copper coil? I would really like to hear more about this aquastack sense it maybe just what I would need to keep our water temps up higher and me from loading the boiler every few hours on cold nights. Any suggestions? 

[Bull]

Welcome to the site Briansbotanicals, I have not heard of these but I am sure someone will come along with some ideas on this.

[RSI]

The problem with salvaging more heat off the chimney is creosote.

If I ever get enough free time I have been planning on trying it out. My plan was make a shell in tube heat exchanger. I was figuring to take a 30 gallon steel barrel and run multiple 3" pipes through it and weld them in. I am not sure how many but probably 6 or 7. (I am not sure how the sizes will come out and might get something different for the outside shell)
Then make an adapter that goes over the end and reduces down to the chimney size at each end.

I figured it would mount horizontal and put a bypass before it so if it plugs it can be bypassed and cleaned when I have time. (instead the middle of the night , etc)

I was planning on keeping it separate from the boiler so I could see how much heat is getting captured.

If I ever do it, it will probably be at least a few months.

[Briansbotanicals]

Sounds interesting.  It seems with the heatmor stove we have creosote has not been any problem YET. The fans tend to push out the smoke fairly fast. When it does seem slow opening the door and getting the fire really hot can burn it out. Of course this works not not sure how it may change if something is added. I have heard that a copper coil around the pipe does not take to much away from the heat inside the pipe. Not sure if this is true but said to work.

[RSI]

You aren't getting much creosote because of the temperature the chimney is running at. They designed the boiler to let the heat escape to keep the creosote from being a problem.

With the heat exchanger I mentioned above it would require cleaning. If it was built heavy enough and was setup to drain out then it could be run empty every now and then to burn it out.

You might be able to have a welding shop make one for a reasonable price. If you do try it let us know how it works. Would same me the trouble of trying it if it doesn't work very good. 

[willieG]

my chimney is 8 inch schedule 40 pipe i have made a 3 foot long piece out of 6 inch with the 8 around it to try on my stove but have yet to install it and give it a go. I have also been thinking of just peeling off the insulation and trying a 50 lentgh of soft copper wrapped around the existing stack and re-insulating with 10 inch  1200 degree pipe insulation i can get from teh chemical plants where i work. this would give the area where the coil is an 1 1/2 or 2 inch gap for teh copper pipe to soak up the heat from the chimney. a small circulation pump will be needed

i am thinking of the copper pipe first as it is the simplest to try and can be installed while the furnace is in operation (or at least taken off line for a short time

[johnybcold]

Insulate, insulate, insulate the more heat you get to the space you are heating the better

[woodman]

Hawken use to offer a catalytic combuster that would drop down the chimney. I guess it didn't work too well as it is not offered any more.

[higgins11]

I'm with johnybcold...........dont focus so much on getting more heat until you have exhausted all efforts to reduce the need for heat.

I insulate the north walls of my greenhouse to help with loosing heat. I'm also in the process of adding thermal (water) storage in the greenhouse. I am burying an insulated water tank under the greenhouse to help hold the heat in the greenhouse. Lots of passive solar houses add barrels of water on the north wall that cool slowly and hold heat in through the night.

 

[Briansbotanicals]

We are heating 4 greenhouses with this unit insulation is not the problem as much as just being over loaded. I may have a deal were I can try this new product out if so I will post any results.

[MTJAG]

I'm with johnybcold...........dont focus so much on getting more heat until you have exhausted all efforts to reduce the need for heat.

I insulate the north walls of my greenhouse to help with loosing heat. I'm also in the process of adding thermal (water) storage in the greenhouse. I am burying an insulated water tank under the greenhouse to help hold the heat in the greenhouse. Lots of passive solar houses add barrels of water on the north wall that cool slowly and hold heat in through the night.

I just finished my greenhouse with black barrels on the north wall and believe me when I say, that's not enough.  In fact, I will run a line from the OWB this summer since I am burning propane every night to keep it above freezing.  I have ten barrels full of water and they do get hot before the sun goes down.  I'm sure they are helping, but when the temps are in single digits or below, it's just not enough.  Briansbotanicals, what are you using inside your greenhouses to distribute the heat from your OWB?

[Briansbotanicals]

I have two greenhouses with heated tables that use a radiant tube system. The water runs directly under the plants. This works best for rooting things up. Once the soil reaches a high enough temperature the pump cuts off.  The other two greenhouses are larger but have heat exchangers that blow hot air out.

 

[RSI]

Are your radiant tubes like these?

[Briansbotanicals]

My system uses the following tubing and set up.

 http://www.trueleaf.net/pdf/Benchwarmer-Bro-2005.pdf

The fin type you have photos of are very hard to get and expensive. I have seen them in older boiler type greenhouses. Usually a few feet under the tables.

[MTJAG]

That looks pretty nice.  I believe I will look into that for my greenhouse this summer.  My question is how do you control the temperature from the OWB to the greenhouse and does the OWB pump need to be able to turn off when there is not heat demand?  Or does it just pump around the clock?