Low intensity radient tube coop heater design done

[Ken H]

designed this and will start building the prototype this weekend. It is planned for 5,000 BTU/hr. with a 90%+ efficiency. Burner and control box will be outside the coop and the radient pipe will be terminated outside also. Design is based on existing tube heaters used in many warehouses.

 

[RocketDad]

Can sched 40 take the heat? Is it an effective heat transfer medium to the coop?

Interesting idea, but I'm skeptical of the design you've presented, both from a safety and efficacy standpoint.

 

[Ken H]

black pipe is a very good medium for radient pipe. The tube type heaters used to all be made from it. The temp of the pipe at the first 3' will be less than 500 degrees and cooler as the distance increases from the burner. It will have to be pitched as the water vapor in the flue gasses will drop below the dew point. The flew gasses should be around 110 degrees F at the terminal end of the radient pipe. I will be doing extensive testing on the temps reached at various distances from the pipe because, as you probably know radient heaters heat objects with little effect on air temps. The floor of the coop will heat the air as it warms from the radient energy. Not shown is the reflecter that will cover the top of the heater tube(black pipe). This (the reflecter) I will buy from a radient heater supply house. I'll post my progress and test data as it's recorded.

 

[RocketDad]

Are you going to run this across the ceiling of the coop, like the radiant heaters in greenhouses? What are you using for the combustion components - are you building this from parts, or adapting an existing product?

I'm intrigued.

{edit to add}

Okay - I'm less confused now. You are using metal pipe - not pvc. Right?

I usually hear sched 40 used in reference to PVC, so I had this horrible vision from your drawing. I almost never work with black metal pipe except in theater contexts. All the remodeling and construction I've done has involved pvc or copper, and sometimes pvc new-work connections to cast iron sewer (ugh - shudder).

 

[Doopy]

Quote:
Me too. Please keep us up to date on your progress. If possible post lots and lots of pictures of your assembly and installation.

OK now for the questions.
1. Natural or LP gas?
2. Will you have an automatic over-heat safety cut-off? If yes where will the heat sensor be located?
3. Will you have a flame sensor? If yes, electronic or ultraviolet light?
4. Will the gas valve be thermostatically controlled?
5. Will the sched. 40 pipe make one pass through the coop and send the exhaust gasses out an open end? Don't forget a screen on the end of this pipe - mud-dobbers wasps love to plug ends like this in the summer time.
6. Will you have a pilot flame with a thermopile to power the gas valve? Or electronic ignition? If electronic, how will you provide the electricity?
7. How will you deal with the moisture in the heat pipe? Sub-freezing weather will play havoc with your gas flow upon start-up.

I'm sure I'll have a bazillion more questions as you progress. I love this stuff.

 

[Ken H]

Yes, overheating will be prevented with a bi-metal limit in the burner section. Propane will be the fuel. The ignition module uses a spark for ignition and the electrode will also function as a flame sensor via flame rectification. The way flame rectification works is whenever an a.c. current is passed through a gas flame it will be turned into a d.c. signel, hence the term 'flame rectification. The module also has a 'trial for ignition' timer built into it. If flame is'nt sensed within 4.5 seconds it locks out for 5 minutes then retrys. All the while the combustion air fan is operating so any combustibles are cleared before retry. The pressure switch mounted on the fan housing must sense a pressure differencial for the ignition module to try for ignition. The radient tube will inter the coop through a heat collar to isolate the hot tube from the coop wall. It will exit the coop through a collar also. As I said before, the tube will have a pitch to it(1/2") so the condensed water will drain(40% of the byproducts of gas combustion is water vapor). Not worried about water changing to ice because most of it will drain during operation and only 18" will be exposed to freezing temps. Any ice formed will melt and drain during the run cycle. I already have electricity to the coop. A thermostat will control the burner. A ranco #ETC-111000 already controls the existing heat (500watts of deep red heat lamps). It has the advantage of a remote sensor that can be located up to 500' away from the control so I'm able to monitor the temp without leaving the house. It's set at 35 degrees F.

 

[Doopy]

Quote:
Sweet! It appears that this will be a purchased control / burner unit. I was picturing in my mind some kind of a home-brew burner. Thanks.

 

[Ken H]

It will be a 'home brew' burner, however one done with over 35 years of commercial/industrial service and design work in the heating industry backing it. A gas oriface sized for 5,000 BTU/hr (.028") will be mounted slightly 'downstream' of a turbulator plate. The plate causes the air entering the heat tube to swirl insuring an even fuel/air mix. It's an old and proven method which eliminates the need for a venturi type burner (the method typical home furnaces use), and is technology nearly 100 years old.