will using a forced air heater work for the first stage of curing?

[Matt916]

My dad has recently bought what is apparently called a forced air heater. this thing runs off of diesel fuel. He seems to think that we will be able to use it instead of a propane burner inside the oven to bring the oven to a temperature of around 300-350 degrees (and keep it there). Apparently this heater is used to heat large areas like a garage.

I'm a little skeptical that this heater will be able to get the oven hot enough. we have been running it for about an hour right now, and i have included a picture of our setup. I just went outside to take some temp readings using an infrared thermometer, and the temperature of the floor is about 340-350 degrees, but the bricks in the dome seem to be only getting to be about 200-230 degrees.

My fear is that it will not evenly enough heat the oven to an appropriate temperature, and when we're ready to build fires, we will get cracks that will leak heat and smoke. I'm really nervous about the curing process because i have put soo much work into this oven, i would be devastated if it got messed up now and would be unable to function correctly becasue the curing was done imporperly. I really need a second opinion on this thing. has anyone ever used this method or seen anything like it and had positive results?

[heliman]

Re: will using a forced air heater work for the first stage of curing?

A common method of curing is to use a gas "ring burner" as an alternative to making a fire. This would suggest that any head source - at the right temperature and allowing the correct air flow to happen would be OK. Dificult to see where exhaust happens with your method - but it does appear that the blower may be blocking the natural exhaust flow of the oven.

[Jed]

Re: will using a forced air heater work for the first stage of curing?

I'd guess this heater will help dry your mortar. It does add heat and it does move a bunch of air.

This will be a gentle way to get the curing started, but at some point the only way to get the job done is to build a fire in your wood fired oven. With a real live wood fire, and the curing schedule James has detailed, you will get the process of curing your oven started.

The curing schedule gets your oven to the point you can build big hot fires in the oven, but it takes a good dozen big fires to get the oven fully 'cured' and to get stable performance from the oven.

There is no up side in worrying about cracks. If they happen, they happen. If they are bad enough, you fixe'm; and if they are small cracks, you live with them. And if your oven doesn't have any cracks, yours will be the exception, most ovens have cracks of one size or another, and they work just fine. One of the beauties of the design of the Pompeii is the design is very strong, even with a crack or two.

Good luck with your oven,

JED

[drogers]

Re: will using a forced air heater work for the first stage of curing?

Having used these heaters in buildings and to thaw out construction equipment I would be hesitant to use one as your father is. My concern is that the large flow of hot air would dry out the most inner layer of the oven rather quickly, setting up stresses. For all of the work you have done, I would suggest that a little more patience is in order. Some times blazing a new trail is just not worth the possible consequences

[nissanneill]

Re: will using a forced air heater work for the first stage of curing?

Matt,
I would have no worries with drying my oven with these heaters but wood fires work just as well. They certainly produce a hell of a lot of Bthu's (or Calories if you are metricated), we use similar ones but mainly run on lpg. Panel beaters use these to heat up and bake their 2 pack coatings quite successfully.
The reason why your dome is significantly lower than your hearth is the moisture is having to be removed through the bricks whereas your hearth is not cemented but simply stacked together. Another reason is that it is not yet insulated as hopefully your hearth.
As the dome dries out, the temp will increase and become almost equal to the hearth.

Cheers.

Neill

[ThisOldGarageNJ]

Re: will using a forced air heater work for the first stage of curing?

Hi Matt,
My only concern with that is, I used to use a similar kerosene heater in my garage, The kerosene would always leave a film on everything that had to be cleaned off, Kind of a light coating of slime.... I'm not familiar how it is with diesel fuel, but I would'nt want my pizza having a diesel fuel taste.. Just check inside the oven and see if there is any kind of coating(slime) on your firebrick.. On the other hand,, When you get to your real fire's it may just burn off if there is anything there
Good Luck
Mark

[Matt916]

Re: will using a forced air heater work for the first stage of curing?

Thanks for all the responses! You were all right about this heater not being a very good method...for a different reason than i would have even imagined. apparently the manufacturer of this particualr make and model of forced air heater makes their fual tanks out of a lightweight plastic. We let the heater run for a couple hours while checking up on it every 10 or 15 minutes. After about 2 hours, i was checking the heater to make sure it was still working properly and upon close examination i found that the plastic tank had completely melted through where it was closest to where the heat was being produced, leaving the fuel completely exposed. needless to say, I immediately shut the thing off. im just glad nothing caught fire or exploded. so any way, what im trying to say is that this was a very bad idea. I would think that they would have made the fuel tank out of a material which would not crack or melt. So, just for future reference, if anyone else was planning on trying this, and they come across this post...not a good idea.

on a brighter note, i built my first curing fire today and got the oven up to a reasonable temperature. I don't know if it is normal, but i couldn't get the dome and the floor temp to match. the floor got to about 400, but the dome was about 300 degrees. hopefully at higher temperatures it all evens out. I guess only time will tell.