Mike Hraber Posted February 21, 2019 Report Share Posted February 21, 2019 Hi all, I’m having an electrician install 2 240v 50 amp receptacles for my newly purchased used kilns. These will be in my basement. Electrician wants to mount them to the rafters which are about 8 feet high and I would plug the kilns in up high. Are there risks or problems with the kiln cord hanging from the receptacle at that height? The gravity weighing on the plug is my concern. My basement has a pvc insulation system on the walls so mounting to the wall isn’t possible. I have plenty of room to position them so that the cords are not dangling close to the kilns. I could also have the electrician run the receptacles down a nearby heavy wooden column to get the plugs more to that 3 foot height but then I’m putting the kilns more in the middle of the basement than I’d like to. Does anyone have thoughts on this? In the photo the red circle is where electrician proposed to put the receptacles. Blue circle is the wooden column I could also use, but it would sacrifice more basement space. Electrical panel is just outside the photo frame - upper left of the shot. And please pardon the clutter! That junk will be out of there once I’m ready for installing. Thanks! Mike Link to comment Share on other sites More sharing options...
liambesaw Posted February 21, 2019 Report Share Posted February 21, 2019 I would run it down the column. I don't think it would be safe to have the wires dangling above the kilns. Link to comment Share on other sites More sharing options...
Dick White Posted February 21, 2019 Report Share Posted February 21, 2019 The wires on the kilns aren't long enough to reach the ceiling. They are hardly long enough to reach a wall behind the kiln after allowing for the required 18-24" of space behind the kiln plus a bit of slack so the wire is not directly touching the kiln body. If you are going to put the kilns near the PVC wall, you will need to install something fireproof/heatproof on the wall so the radiant heat from the kiln doesn't damage the wall. By the time you install a stud structure for that, you might as well put the electrics on the same framework. While you are at it, install cut-off switches before the receptacles so you can just reach over to completely cut power to the kiln rather than scrambling to find the main panel and circuit breaker. Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 21, 2019 Report Share Posted February 21, 2019 Rafters not so good since this is your form of disconnect, even if he mounts them vertical. Mounted horizontal would place too much strain on a typical cord end. He could build a freestanding unistrut frame anchored to your floor and mount them behind or to the side of each kiln but he has to run feeds to the stand from above or along the floor. He could frame off the kiln legs with strut or angle and mount them a convenient height in back or on the side of your kiln. Maybe feed from above but this makes moving your kiln a bit of a chore. last question, can you glue a 3/4” plywood backer board to the wall from floor up to approximately 3’ so he can just mount the outlets on the wall. Plenty of real world industrial adhesives for this. No glue installation: bolt angle at floor or clip angle to hold backer to wall, install two short knee braces bolted to floor to hold it against wall. Wood can be covered with drywall to make it more heat resistant. Looks like you will need a hood above the kilns to remove excess heat as well. Column seems simplest at this point but I can think of lots of ways to do this. Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 Thank you all for your thoughts. I’m asking him to do the column now. It just makes more sense. I’ll also ask about cutoff switches too...good idea. Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 Ah the excitement of setting up kilns but I just thought of another concern I want to ask about : see the location of my natural gas service. In upper left of shot. How much distance should I give between the gas equipment and the kilns? My furnace and hot water heater are nearby as well. I’ve been assuming these are all okay with 2-3 + feet of clearance. I guess the wooden column is also combustible so I need to think that through too. I’m thinking 18” is okay for this but I need to keep reading through the L&L manuals. I am also reading through L&Ls specs on BTU loss and venting the room and this stuff is complicated. I will have a downdraft vent for both of them as well but I’m just wondering now if I don’t have the right place for 2 kilns to run simultaneously. One is a Jupiter 18x, and the other is an easy fire 23s-3. Maybe I need to invest in more ventilation into this part of the basement. I do have access to the outside from the basement and could set up fans to blow air into the part of basement where kilns will be. I hope this makes sense. Thanks! Mike Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 21, 2019 Report Share Posted February 21, 2019 This type of vent is likely most effective in your situation or will give you an idea. Several folks make them and some potters make their own. You will need to be able to bring in fresh air to offset the exhaust and not to pull any co from your gas appliances. Your current gas appliances should have a makeup air supply sized for them, if not this can be sized into the makeup air supply for the exhaust. Co detector and at least a rate of rise heat detector probably wise addition as well. Quick video of the thought process and measurement of what we did for commercial replacement for a failing downdraft with a supplemental pickup above the kiln to intercept wax burn-off. We may still change it to a hood instead of the exhaust grill. Your setup would need to be designed to accommodate your environment and concerns though. The kiln is not an exposed flame device absent any gas leaks the meter likely is not an issue. All the more reason to ventilate properly I guess. Link to comment Share on other sites More sharing options...
Mark C. Posted February 21, 2019 Report Share Posted February 21, 2019 I saw your gas meter 1st-I'm a gas man. the 3 feet is fine . Put the plugs on the column near your blue circle-18 inches is fine for clearance. Work on planning the vent system next.This also will take some thinking. The vent system will take 110 volts so plan your outlet while electricain is there. Link to comment Share on other sites More sharing options...
neilestrick Posted February 21, 2019 Report Share Posted February 21, 2019 I'd go with a Vent-a-Kiln hood on a swing arm. With the kilns side by side, you can swing the hood over to use on whichever kiln is firing. The hood will do a better job of venting heat than using fans, as it fits right over the top of the kiln. The exit flue will only need a 5" opening to the exterior. Fans will work, but will only work well if you've got air moving out as well as in. Otherwise all that heat is staying in the house, it's just being diluted a bit. You'll notice a definite warm spot in the room directly above the kilns. Keep 18" clearance from anything flammable. If you're concerned, install a layer of cement board (tile backer) to further protect areas. Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 21, 2019 Report Share Posted February 21, 2019 The vent a kiln is an exhaust so still don’t forget the makeup air from outdoors. No use sucking flue gases back into your basement, when your kiln exhaust kicks in. I believe their smallest is approximately 250 cfm. Link to comment Share on other sites More sharing options...
hitchmss Posted February 21, 2019 Report Share Posted February 21, 2019 Id put the kilns where you can easily vent them, and run your electric to that location. Neither where you or your electrican circled a spot that I would put a kiln. If you have a door, or a window in the basement where your exhaust lines can run out, thats where Id put the kilns. Being that they are in the basement of your home, you really dont want to be leaving all those fumes/gasses in your house to be breathed in. Bisques are bad enough, glaze fires are worse. If you put the kiln in the center of the room you're going to have to step over, or run an exhaust tube/pipe to your exit, which means reduced air flows. Keep your exhaust runs as short as possible. Also, when exhausting/venting, you need to bring in as much fresh air as you are blowing out, so if you have a window on the opposite side of the house from your exhaust, open it while firing. Try not to locate your exhaust under a window that you might have open in the spring/summer which would bring the fumes right back inside. Otherwise, like others said, observe your combustible clearances, and there are plenty of ways to get an outlet close to your kilns. Link to comment Share on other sites More sharing options...
Rae Reich Posted February 21, 2019 Report Share Posted February 21, 2019 Sounds like saving money on electrical installation will involve many complicated adjustments/expenses. Mark is right about locating kilns near an exterior wall. Check general wind direction too, that will factor into whether exhaust blows back into the house. Have you drawn a diagram of the area to think about all the possibilities? Making little to-scale cut-outs of your furniture and equipment to move around the diagram can inspire In the meantime, some outlets on the column will always be handy. Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 Thank you all so much for your thoughts! The electrician is going to kill me lol. I have clearly put the cart before the horse with my planning here but there is still time to do it right. I have a big beautiful finished room, an addition to the basement, that I wanted to be a dedicated studio work space that has much easier access to an exterior wall. I would have to sacrifice some of that space to get the kilns into that room but yeah, getting electric in there will be easier than the contortions to get the venting to the old part of the basement. Thanks so much for the food for thought! Link to comment Share on other sites More sharing options...
Mark C. Posted February 21, 2019 Report Share Posted February 21, 2019 You only have one chance to lay it out right-the kilns should as Hitmass said go next to an exterior wall with windows . I would not put kilns in middle of room-also think about work flow.Hold off the electrician until you get the layout right. Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 Here is a diagram with 4 different kiln locations and two different basic runs for exhaust vent. I was really hoping not to put them in the nice finished studio room but it’s definitely the easiest place to get through the wall for exhaust. Ugh. I don’t mind losing the big chunk of space in option 1 because it’s just a big storage room down there. The drawback there is it’s a very long exhaust run and getting fresh air in is tricky. Option 2 has shorter exhaust run and it’s more in a corner but the PVC wall system cannot be screwed into. Maybe I could epoxy some kind of board to screw the circuits down onto. Options 3 and 4 sacrifice space and aesthetics in the main studio work area but they are very close to the wall and I can open the back door to let fresh air in. I might be venting in exhaust fumes if the wind blows the wrong way but often times this would be less of a problem. This room also has higher ceilings so more air here as well. Sigh the more I think about it I, like putting them in my nice finished studio room. Link to comment Share on other sites More sharing options...
neilestrick Posted February 21, 2019 Report Share Posted February 21, 2019 With the L&L Vent-Sure downdraft vent, you can run up to 60 feet of duct with up to 3 elbows. So you've got a lot of play there, but you'll need to figure out how to bring in cool air. With the Vent-a-Kiln overhead hood, it doesn't give specifics on how long the run can be. I would give them a call to make sure, but I would imagine a 10-20 foot duct run shouldn't be a big problem, especially if it's pretty straight and the vent motor is somewhere in the middle of the run. I don't think makeup air is going to be much of an issue in a room that big, especially if the door to the upstairs is open. That door to the outside would probably work fine if needed, since it's around the corner. Kind of depends on which way the wind is blowing, though. Are there any windows in either space? Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 No windows unfortunately it’s mostly below ground down there. Just the one door to the outside. I have the L&L downdraft vent and was hoping not to buy another system in addition, but I can add a hood if the heat is just too much. I can leave the upstairs door to the basement open and run a fan pointing out from the old basement toward the back door. I think that will give me enough airflow at least to make up for the downdraft vent. This would also vent some of the heat. I’m just not sure how much heat I’m gonna have and the math project with the BTU table seems daunting to me lol. Link to comment Share on other sites More sharing options...
neilestrick Posted February 21, 2019 Report Share Posted February 21, 2019 Start with the downdraft vent. You can run both kilns off it. If you find there's too much waste heat coming off the kilns, add the hood later. Adding a layer of insulation and drywall or cement board to the ceiling in the kiln area may help with the heat coming up directly above the kilns radiating into the space above. Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 21, 2019 Report Share Posted February 21, 2019 The exhaust can be ducted so a typical design would be an exhaust above each kiln if you intend to concurrently fire. A typical design would allow the exhaust to exit on one side of the house preferably away from open windows and in excess of ten feet from any combustion air supply and away from neighbors. I would not let this drive my functional design as the size duct runs and quantities of air we are talking about are small and relatively easy to run. Using a hood to capture the burn off is far more effective than the down draft device, Check out the - vent a kiln - video.. A typical overhead exhaust will be approximately 250 - 500 cfm. Most important to the whole discussion is letting outdoor air in or as we say in the bus. makeup air so an adequate anount of fresh air is supplied to offset the exhaust and that required for your gas appliances Google combustion air requirements or make up air. My suggestion, take some time to understand this and do your best to understand how this stuff really works, I see many well intentioned comments about opening windows and doors etc... which can be good but often result in a poorly designed system that does not perform consistently, when pressure gradients change because the wind is blowin North today. I taught this stuff for 20 years so a solid design beats opening windows etc... any day in my experience. Down draft systems exhaust well below 50 cfm and most often below 25 cfm. They really do not influence or control temperature to any real degree. Link to comment Share on other sites More sharing options...
Mike Hraber Posted February 21, 2019 Author Report Share Posted February 21, 2019 Great points everyone. Thanks again!! Mike Link to comment Share on other sites More sharing options...
neilestrick Posted February 21, 2019 Report Share Posted February 21, 2019 A dowdraft vent does nothing to vent heat. It only vent fumes. But it does a great job with the fumes because they're pulled directly from the kiln. Downdraft vent fans are rated at about 130cfm. They pull a small amount of air from the kiln- just enough to pull out the fumes-and mix that with a much greater amount of air from the room, so the air in the duct stays under 140F at the motor, about the same as a clothes dryer, and further cools as it goes through the duct. Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 21, 2019 Report Share Posted February 21, 2019 1 hour ago, neilestrick said: A dowdraft vent does nothing to vent heat. It only vent fumes. But it does a great job with the fumes because they're pulled directly from the kiln. Downdraft vent fans are rated at about 130cfm. They pull a small amount of air from the kiln- just enough to pull out the fumes-and mix that with a much greater amount of air from the room, so the air in the duct stays under 140F at the motor, about the same as a clothes dryer, and further cools as it goes through the duct. Interesting, I recently measured one of these and got about 15 CFM combined discharge from two pickups with the factory holes all open in the pickups and the factory plastic ribbed plastic tubing run into the factory inlet manifold. The blower discharges into a fairly straight 4" discharge duct (Galv. Steel) with a fairly low back pressure vent cap and two elbows. That's a long way from 130 CFM but if I look at the volume of air possible through all the tiny holes, small ribbed pickup tubing etc.... on the inlet side I believe the friction loss of the restrictive fittings etc.... accounts for this. I used to explain to my students (When we all smoked) light a match and blow it out - Easy! Light another and suck it out - not Easy! While these blowers have free air ratings around 130 CFM, they likely never discharge that as designed and as a result are likely not intended for cooling. I like these counter flow systems actually and they do work well but do not believe they intercept all the off gassing. Its simply too difficult to suck out the match. The slightest local air current and the temperature difference causing the air to rise is likely far too great to overcome with a few 1/4" diameter holes drilled and -0.1" to -0.2" of static pressure measured at the pickup. The vent -a-kiln video shows this clearly. In someone's house I always suggest at least a hood or both systems. One add - when possible for exhaust we prefer to design the ductwork as inlet duct assuring that any leakage will be into the duct. When designing as outlet or pressurized there is the possibility of pressure leaks of the stuff you are trying to exhaust. Even well fitted sheet metal duct usually grows to a few percent leakage over its lifetime. If given the choice where to install the fan it would be nearest the discharge opening to minimize pressurized duct run reducing the possibility of pressure leaks. Rooftop mounted exhaust fans are popular for convenience and a biggie - no discharge duct required. Link to comment Share on other sites More sharing options...
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