Heatilator Model ND3630I
While installing gas meters today , I noticed that one of our many new home builders had installed a couple of the Heatilator ND3630I Direct Vent Fireplaces in two of their new homes. These particular units had the Intellifire ignition system which utilizes a 3 volt control box and spark ignition for the pilot along with a variable Dexen control valve. This unit is new to me and I was just curious as to how reliable this ignition system is? Are these a new system or have they been around awhile? I did notice in the owner's manual that the back-up battery pack and the 3volt transformer cannot be used at the same time, either one or the other ,and if using the transformer the batteries cannot be installed in the battery pack! I also noticed that the wall mounted wall switch for the fan must be wired with a 14-3 wire from the switch to the junction box, a little bit different from what I'm used to seeing. Anything in particular one should be aware of when trouble-shooting this system?
HHT's Intellifire IPI system
It's been pretty reliable compared to standing pilot systems. There were some initial bugs but HHT flew some engineers over to China and corrected the quality issues with the Dexen valve pretty much except a few quirks.
With a standing pilot, you must first light the pilot then turn the control knob to 'on' in order to get readings at the gas pressure taps. With the Dexen, as long as the gas cock is open, you have inlet pressure at the tap. No mechanical failsafe. You cannot adjust the pilot flame with the Dexen. When converting fuels, you can swap out the burner solenoid. However, there is a relatively high complication rate on field converted valves. There is a delicate flat O ring which gets easily crushed and everyone tries to use the wrong scwer holes. Need a tamperproof Torx-T20 bit.
The new PSE pilot is much more reliable than the old Robertshaw 3 way flame, which needs a grounding strap at the right hand screw retaining the pilot assy. Needs a good ground.
If you install two D cell batteries, it will suck them dead first then look to the 110vac. Therefore, they came up with a Cabin Kit to do the switching for you. Now their new WSK 300 wall control has this function built right in.
The brown wires always are your on/off circuit and are low voltage, even with power venters and remotes or stats.
The new fan kits use a timer so the fan kicks in after 7 minutes of burning and shutoff 12 minutes after burner shutdown. However, if you elect to control it with a wall rheostat, you'll need the 14/3 in a switch loop.
In normal ignition, it will continue to spark for 60 seconds. Once good flame rectification is sensed, should it lose the signal, it will attempt to relight x 1 minute.
If you need a standing pilot for that ~1,200 BTUs behind the glass or to prime the flue so it drafts out of the starting gate, you can select Cold Climate function on the wall control or buy the kit.
This system tolerates wide swings in flame rectification. I've seen it run with 0.2 to 12.5 microamperes.
In high humidity, some units fail to get good rectification until the flame rod's non-vitreous ceramic insulator dries out. Not a problem with the PSE pilot.
Test you ground and polarity. More than about 5 mv ac on the neutral can freak it out. Did I say needs a good ground?
When handling, don't allow valves to be tossed around. The potting in the valve can give way allowing things to move around inside. Treat it like a precision component..............that was made in China.
IPI has been around with furnaces for over 12 yrs. now. Just when we get comfortable with this system, we'll begin switching over to UV detection.
Keep the fire inside the fireplace.
Thank you for the detailed reply hearthman, great info!
you dont have to wire the j-box on a switch at all!. if you MUST then you should use 14/3 so that the black can be always hot for the IPI system and the red can be switched for the fan. FYI. You should always run the low volt switch wire with 18/3 at a min, no more 2 wire for fireplaces.
Thank you as well jtp10181, this site is a very useful tool for information and I do appreciate everyone who replies to my questions as I continue to learn in this trade.Thanks again
I haven't encountered this ignition system ----yet.
Hearthman gives a good deal of detail, but I can't really envision how the details work together, although I've had plenty of experience with intermittent pilot systems in furnaces.
I'd be interested in a booklet designed to explain this system to technicians, if such a thing is available in paper or on line.
Mfrs. tend to hold such info. for their own dealers. However, most anyone willing to pay may take their technical training, which includes using table top boards can sign up. These boards have a Robertshaw standing pilot on one side and a Dexen IPI on the other. It runs off a 1lb. propane bottle. Students are given DMMs, a manometer, and tools to take the basic readings and tests, which you record on an answer sheet, which along with about 30 questions gets graded to see if you get a piece of paper to hang on your wall. No, you have to return the instruments and boards.
Here is the basic sequence: polarized unswitched 110 vac enters the mfrs. junction box where a plug-in transformer knocks it down to 2.8-3.2 vac. This enters the green module via two leads with clear silicone insulators. You can also power it with an attached battery pack holding 2 D cell batteries, which have red and black leads into the module. When the brown wire circuit is closed on a call for heat, the orange igniter wire starts the igniter sparking as the other orange wire sends ~0.98 vdc to the pilot solenoid, which then flows gas to the IPI pilot burner. The spark gap is 1/8th to 3/16ths".The pilot flame ignites and current is sent via the white or blue sensor wire to the flame rod. Through rectification, a DC microampere signal is read by the module confirming the presence of a flame. The igniter DCs as the voltage to the pilot solenoid drops to about 0.46 vdc. The module sends about 1.09 volts dc via the green wire to the burner solenoid to open and the main burner fires. The pilot solenoid has a normal resistance of about 37 Ohms while the burner solenoid has about 55 Ohms. Fuel consumption by the pilot burner is btw 1,200-1,600 BTU/hr. Should the 110vac to the transformer open, the unit will shut down. Upon restoration of power, the unit will not try to restart. A human must cycle the switch on the brown wire circuit (rocker, remote, or T'stat). Oh, yes, there is a black ground wire off the module that must go to a clean, low impedance ground. Inlet pressures are 5-7 wci NG/ 11-14 wci LP and manifold pressures 3.5/ 10.0 NG/LP. There could be a N.C. high limit swich in the brown wire circuit on some units. Those DC voltages to the solenoids run slightly higher off the battery pack and the igniter sparks a little faster than off the transformer.
There are other advanced systems you may find including the Cabin kit, Cold Climate kit, multi-function remotes and wall controls, power venters, etc. but this is the basic system.
Other than this, I'm not too familiar with this system...
Keep the fire inside the fireplace.
Is all that to save the heat or cost of a pilot?
there is also no thermocouple or thermopile that can fail.
I Love IPI
The decision to use any electronic ignition system over a standing pilot is based upon conserving fuel and removing an open flame from possible combustible vapor clouds, such as water heaters in garages. Since fireplaces with electronic ignition and almost all direct vent, the second hardlly affects Fps. California has now outlawed standing pilots. Since they are a bellwether state, others are sure to follow.
As a mfr., HHT saw the IPI system as more reliable than other forms of electronic ignition such as Direct Spark Ignition and Hot Surface Igniter but also felt it would be more reliable than the venerable standing pilot. They track the Customer Complaints per Million and Serice Call Rates to spot trends with problems in a particular component such as a limit switch or a subgroup such as a valve or pilot assy or IPI vs std. pilot. So far, the IPI was ahead of the game.
The main problem mfrs. have in such cases is getting good clean data. If you go by the raw calls, it may look as though you have a defective product. However, when you drill down you see there was a surge in a new market you opened. Upon investigation, you discover low inlet gas pressures are rampant. After a little remedial training with your sales force and field ops. folks, the rates drop off sharply. You didn't modify the equipment, you modified the behavior of people. That's what IPI is about.
When its off, there is no gas flow, thus saving the 1,200-1,600 BTU/hr from a pilot flame. When its on, you still have a pilot flame igniting and maintaining the burner. Unlike DSI, where you rely on the main burner flame's stability for rectification, IPI only needs a stable pilot, which is far easier to accomplish under all conditions.
There are drawbacks to IPI. Some fireplaces need a little draft in the flue to prime and get going. A cold start may deoxygenate and shut down requiring you to cycle it 2-3 times before it gets going. Another drawback is some homeowners like that little bit of heat behind the glass and complain it is a cold spot in their wall. Yup, it's full of cold air from outside so HHT can up with a way to defeat the intermittent function and make it standing pilot if need be. One of the biggest drawbacks to DSI was lack of backup power during a power failure. The HHT Intellifire system uses 2 D cell batteries, which makes it convenient. There are units that require 110vac for blowers so they are not Intellifire and cannot use the battery backup. They could run off a generator or car battery with inverter.
Keep the fire inside the fireplace.
Thanks for your description of this intermittent pilot system, Hearthman.
Personally, I've always thought that 24 VAC intermittent pilot systems for furnaces were the best of all possible ways to light a burner. Some of the Honeywell ignition control boxes were really excellent ----I've had one in my furnace for 21+ years and it's worked great, and I've changed out few of those control modules over the decades.
I'll have to print out this thread and you posts in particular so I'll have it when I encounter this system.
Do you know how many microamps are needed for the system to prove a pilot and where to measure that current flow? Even 24 VAC systems could have problems getting sufficient current flow to prove, and since current flow through the pilot flame is usually propotional to the voltage I wonder if that can be a weak point.
Also, silicon oxides on flame rods or other sensors can act to insulate and prevent the flame proving currents needed, especially with low voltages. Any indication if we are going to be out there cleaning dirty flame rods rather than dirty pilots?
I hope the unit includes some rtv silicone (red) otherwise there will be many unhappy canadian customers with cold walls. Ironically they will spend more money to keep the wall warm than they would on a pilot system. More work to get the spider out every fall also.
Those in Canada are not the only ones who would want a pilot on. That is why HHT offers a number on new wall contols where turning the pilot on is a feature. The new series WSK100, 200 and 300 all offer the ability to turn the pilot on, leave the batteries in while run on 110 and verify that the batteries are not dead. There are times of the year that it is so bitter cold that you want your pilot on and if you live near water, ie beach houses, it is best to leave the pilot on due to the high humidity or salt air. Keeps the box from rusting more than normal...