"biofriendly studios" input

[Hugh Jenkins]

As part of the "biofriendly studio" panel at GAS in June, I want to know what uses people are making of "post-furnace" heat. What I mean here is regardless of gas or electric (or oil) as fuel, and recuperation, what are any of you doing with the remaining heat from your shops (furnace, glory hole, etc). There have been hypothetical discussions about hot water, building heat, pool heat, worm farm heat, etc.

What we want are actual applications that are in operation. If there has been a cost benefit, that would be great info too. We will credit sources unless asked not to. If privacy is preferred, you can PM or email me.

This panel is turning out to be very interesting and even fun in our monthly discussions. New stuff keeps coming up. The panel and Journal report will be our way of giving out what we have learned and are working on in our own projects.

[Rich Samuel]

Let's get this out of the way first: cooking brisket. :D

[TC Robertson]

We recuperate our gas furnace and get around 500F air into the burner. Then the air is sent into one of 2 ovens. They get about 75% of the energy from the flue gases. It does vent into a little chamber that could cook brisket, but we have never used it for much. It's hard to cool down. Twice inspectors have asked me where the flue comes out. I use split bricks for dampers, that slide sideways. My gas bills were $1000-1200 with a 300# pot, charged once+ a week and 2 13" holes going 4-5 days a week. Electric bill is still under $100 a month. I only have a 100 amps in here. The new 20"-16" hole and 475# pot will certainly have an effect the the nat. gas bill. The hole is open on both ends to let out heat extra fast.


Hugh, how did the Kauai oil conversion job go? I may get out there in April and want to see it. Later, TC :D

[Ken Peterson]

when I was living at my old shop, I stripped the insulation off an old water heater, took the tank and put it behind the furnace (not touching, just in an area that was always warm). I hooked 2 hoses up to it. One attached to the faucet outside, the other was my shower for two years.

In the summer it was too hot. In the winter it was luke warm when I first turned it on, and it pretty quickly went cold. I wish it was the other way around.

I'm glad those days are over!!!!

[Hugh Jenkins]

TC, the Kauai furnace build with 3' stack and recuperator has them very happy. Big budget advantage, even running hot and charging almost daily. But with the previous electric furnace working off of $.33 per kwh power, the bills were pretty large. The oil conversion is still on hold, waiting for tank, slab, and collection approval. We are hoping for February now but not sure. I also plan to put the 4 foot ceramic core stack on when we convert, but may do it sooner for the sake of comparison. They are willing to support the research progression for the sake of grant validation.

[Pete VanderLaan]

At one point I ran a 250 foot coil of copper line inside my hood above but never touching the furnace. It went into a 100 gallon tank and constantly circulated. It could be drawn out at any time and fresh cold water replaced what was removed. I consistently had 120F hot water and never needed a water heated. This will work poorly with an electric furnace.

I also recuperated all of my gas furnaces.

[Mark Wilson]

a lot of the waste heat from my curcible kiln, annealer, and glory hole is utilized to heat my home during the fall/winter/spring. when the glory hole is hot, i do ventilate a lot of its waste heat outside, so that heat is lost, but the minute i am done blowing for the day, i shut down the ventilation and the waste heat will keep my home nice and warm all weekend long, until i shut down the crucible furnace.

[Charles Friedman]

I have 15 feet of 3/4" copper tubing coiled around inside of a insulated box set on top of my pipe warmer. The flames go thur the top of the pipe warmer and exits out the top of the box. A small circulating pump, pumps water via garden hoses and into a 8 foot oval stock tank. Makes for a great hot tub.

[Steve Adams]

The glass furnace and glory hole here help to heat the house all winter. The exhaust stacks from each join up to a two stage heat exchanger that is located just outside the studio. Water is heated and pumped 5’ underground through well insulated ¾ copper pipe to the house 50’ away. Those lines connect to another heat exchanger in the house that is in the cold air return which is connected to the intake of a of a high efficiency gas furnace. This system uses the fan in the forced air house furnace to supply hot air to the ductwork in the house. That furnace only comes on if the studio isn’t supplying enough hot water at night to heat the house. The whole system is automatic and run by two thermostats. If it is 40 degrees outside the system can get the house up to 80. When it’s below freezing outside the house furnace must go to work but the recovery system still helps it out. The heat exchangers are recycled “A“ coils from air conditioning systems re-plumbed for water. I would guess the system delivers 30,000 btu’s to the house and saves $200/month and has been in operation for 25 years.

[Hugh Jenkins]

Mark, are you using a heat exchanger of some type to move heat to the house?

Steve, I sure wish I had been more aware of this stuff when I visited up there 10 years ago. How are the under ground pipes insulated? Your distance from shop to house is about the same as mine. You would be surprised how often we light up the wood stove to warm up and dry out the house. Snow on Mauna Kea makes for a chilly draft down slope.

[Steve Adams]

The pipes were covered with 1/2" amraflex and laid into a box made of 1" styrofoam and then buried. The total length of pipe from the shop exchanger to the house exchanger is probably 100'. A few years ago I added a large powered updraft fan to the top of the stack and that made a nice difference. The exchanger at the shop is twice the size of the one in the house. A hot water thermastat doesn't let the house blower turn on until the water temp is up to 125 degrees. At the momement, it is snowing outside and the house is at 73...

[Michael Mortara]

After surfing I dry all my wet stuff by draping them over my furnace, rather than putting it in the dryer.

[Steve Adams]

update... the furnace and glory hole were turned down or off 4 1/2 hours ago and it is still snowing and the house has dropped to 70...

[Mark Wilson]

Originally posted by Hugh Jenkins
Mark, are you using a heat exchanger of some type to move heat to the house?

no my studio is in a 8x14 foot room in my basement.

[Steve Adams]

I just came in from the shop and tonight it is 15 outside and the house is at 70, totally from reclaimed heat. The house is a 1901 farmhouse that has been remodeled but even most of the roof is framed with 2 x 4's so insulation is minimal...

[Hugh Jenkins]

Thanks Steve. This is a great reference for reclaimed heat. I hope others follow suit. I will have to rethink how far it is practical to pump hot water.

[Bob Dupee]

Hey Steve...nice to hear about your studio. I'm just N of you about 2 1/2 hrs in christina Lake,BC, and would love to come & see your set-up sometime. We are building a studio complex here, and want to go for LEED certification of the building; obviosly, the heat recycling is key to that. You have done what most of us should be doing in this age of climate change. Do you have any pics that we could see to help make it more tangible to the architect?