FAQs for Orton VentMaster Kiln Venting System

FAQs for Venting

How hot does the ducting get during the firing?

When installed properly, the Ventmaster is designed to introduce fresh air through the collection cup mounted under the kiln and mix it with the hot gases being drawn from the kiln. The blower motor is capable of moving 70 CFM of air. The size of the holes in both the side of the collection cup and the bottom of the kiln are sized to draw one part of hot kiln air and mix it with 69 parts of room air. The temperature of the air inside the collection cup can be up to 160 degrees F. Once it travels through the three feet of high temperature black hose into the blower the temperature has dropped to less than 110 F. By the time it is exhausted to the outside it is well below 100 F, given that the room temperature stays below 75 F.

Will the fumes coming through the vent damage my plants, the neighborhood pets or disturb the local environment?

No. The fumes and the gases coming from the kiln have been diluted with enough fresh air to make them safe for the environment.

Will using the Ventmaster cause my firing to take longer?

The Ventmaster system pulls only a very small amount of air out of the kiln, so very little heat is removed and firing times will change very little. As air is heated it becomes lighter, (like in a hot air balloon), so, the hotter the air gets, the less dense it will become. Because the air gets lighter as it becomes hotter, the amount pulled from the kiln will decrease as the temperature increases. At the peak of the firing, the Ventmaster is drawing significantly less air from the kiln. Therefore, it does not have a significant effect on the firing time.

Can I mount the collection cup to the side of the kiln instead of the bottom?

Yes, as long as you have a flat surface onto which you can mount the cup. Make your hole (or holes) by drilling from the inside of the kiln out. Locate a spot where there are no heating elements and drill your hole through the kiln. Attach the collection cup with self-tapping sheet metal screws so that the hole is within the 4³ diameter cup.

How much does it cost to operate the Ventmaster?

The Ventmaster typically costs less than 1 cent/hour to operate (electricity costs). The Ventmaster can save on heating and cooling costs when compared to hoods. Hoods remove massive amounts of air from the kiln room “ air that may have been heated or cooled, depending on the time of year. The Ventmaster will remove 80% less air in the kiln room than does a hood, resulting in savings on your heating and air-conditioning bill.

How do I take care of my Ventmaster KilnVent?

The first step in obtaining proper performance and long life from your Ventmaster system is to keep the interior of the kiln clean and to make sure that the holes do not become blocked. You also need to keep the blower motor free of dust and accumulated dirt. It should be vacuumed often. Try to keep all dust and debris out of the Ventmaster fan and plenum area.

What is the best way to mount the collection cup to the kiln? Is any one method better than the other?

The Orton VentMaster has the unique feature of allowing the user to mount the collection cup to the kiln in three different ways. The cup can either be attached to the side of the kiln using sheet metal screws or it can be mounted under the kiln using the adjustable pedestal foot or spring loaded foot. There is no difference in performance between the three types of mounting. The method you choose will depend on personal preference.

Do I need double wall duct when going through the roof?

You do not normally need double wall ducting when going through the roof since the pipe or duct does not reach high temperature. It is always advisable to check your local building codes for their requirements.

How do I attach the collection cup to the bottom of my kiln?

The collection cup assembly is designed so that the cup will be held in place simply by adjusting the height of the pedestal. There is no need to attach the cup to the bottom of the kiln with screws, the compression alone will hold the cup in place.

How long can the 4³ diameter duct be and how many bends can it have?

Up to 60 feet of ducting containing four 90 degree bends may be safely used with no drop in static air flow at the duct exhaust point or a reduction in draw at the kiln. The ducting can be run either horizontally or vertically.

Will the cold air entering the kiln damage the product?

The amount of air that is entering the kiln is so small that it does not cause problems with the ware. The top holes are placed toward the outside of the chamber area so that no air comes down directly onto ware that is placed near the top of the kiln.

Will faster cooling crack the ware if I leave the KilnVent on during the cooling cycle?

No. Some kilns can cool an average of 4-12 hours faster with the use of the vent system. The cooling is faster but it is taking place at an even rate throughout the kiln avoiding uneven stresses being placed on the ware. Most ceramic ware can be cooled more quickly if the cooling takes place at an even rate. The rate of cooling increase will depend on the kiln size and the density of the load.

How do I know if the Ventmaster system is working?

The easiest way to test the operation of the Ventmaster is to conduct the "match test". Close your kiln and make sure all of the peep holes are plugged. Turn on the Ventmaster. Light a match and place the flame directly over and level with one of the holes you made in the lid of the kiln. The bottom of the flame should be gently pulled into the kiln as a result of the downward draft created by the Ventmaster. If you do not see the flame behave as stated, check to see that you have the appropriate number of holes in the bottom of the kiln. Refer to the owners manual for additional trouble shooting tips.

What should I do if I still smell fumes?

If you still smell fumes after hooking up the Ventmaster system then you should check to make sure all of the holes drilled in the base of the kiln are located within the collection cup. You should also check your ductwork to make sure it is properly connected and that the joints are sealed. Make sure you have closed all of the peepholes and check for gaps between the lid and kiln and repair these if necessary. It may be necessary to add one additional 1/4 inch hole in the bottom of the kiln to increase draw.

What type of duct do I use if I need more than 8 feet?

You can use more of the flexible aluminum dryer ducting or you can use galvanized furnace ducting. We have also had people using "pvc" plastic piping with good results. You should always use the recommended diameter of pipe listed in the owner's manual.


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