Hayward H250IDL2 Ignition issues - IF Code

Sitkom · Nov 18, 2018

Hello all.

Done extensive reading and analysis of voltages and sensors and am completely baffled as to why this thing won't light. IF code after 3 lighting attempts as usual. It is a barely used heater recently converted NG H250 induced draft low NOx to propane (new burner orifices and White Rogers NG-LP conversion kit for the exact valve - consisting of a spring and 2 stickers, lol.) Just got a new 120 gal LP tank and 11" WC pressure to the valve. Valve confirmed working (bypassed board and manually opened valve to light burners to ensure flow - not for the faint of heart, btw.) The valve regulator is screwed nearly all the way down to ensure plenty of flow - maybe too much flow?

The heat exchanger is like new as are all the sensors/ignitor. I bought & installed a new ignitor - no change. the flame sensor looks new, but just to make sure, I have an identical generation H400 and have interchanged flame sensors, control boards, ignitors - no change - same behavior.

This thing has never lit. It's not like it lit and is not sensing a flame and then shuts off. I hear the gas valve open, hear the gas flowing - 4 seconds of lighting attempt and then off. Display is fine, blower's fine. 110V and 24V sources all check out. The ignitor is cherry red during lighting attempts. What the actual 'F' is going on?

None of the prior posts on similar topics address this particular behavior, especially considering I have completely dusted/cleaned/vacuumed this unit and all orifices are brand new as is the condition of the heat exchanger/blower.

Any insight appreciated!

danpik · Nov 19, 2018

If you have the unit to the point that the igniter is working, gas valve opens and gas is flowing, then the only problem is the burner tubes. Are you sure the orifices in the tubes are clear, air doors are open and gas flow is actually coming in contact with the igniter? Also, Cherry red on the igniter??? should be almost white hot.

Dan

Sitkom · Nov 19, 2018

Thanks Dan,
Yeah, it's weird. The tubes are clear and the fan/inducer is pulling serious air in the intake manifold/orifices. I have a little butane hobby torch and it can't stay lit in the manifold airstream in front of the orifices. The ignitor does get well past red - it's brand new. I removed it to inspect while it was doing an ignition cycle. I stopped the ignition cycle before it got 'white hot' as I didn't want to leave it out of the air stream for fear that it might get damaged/overheat.

All I can think of is that the propane/air mix is too dilute to ignite, but I don't know how to adjust/change that other than via the propane valve regulator. It smells of propane out the exhaust every time it cycles. The gas valve is basically full open and I've tried various regulator adjustment screw settings on the valve from nearly closed to full open. Is there a way to adjust the inducer?

The burner tubes look pristine. There's no blockage. Could the inducer/fan be pulling too much air and the mix is either cruising right past the ignitor or it is too propane-light to ignite - or it's just not cycling long enough to allow the propane concentration to build to ignite? The ignition cycle is pretty brief, but both of the control boards I have used exhibit the same timing of 3-4 secs, so it's probably cycling as designed.

One other item of note is that I did convert it to 120v from 240v operation to save breaker space in the panel. I swapped the voltage jumper plugs on the power board in the process. Wonder if that would contribute to the ignition issue? I'm getting just barely 110v (109.7v) at the ignitor terminals (ignitor disconnected) even though the line voltage is 122.8v. With the ignitor connected, I have noticed that the ignitor voltage cycles from 108v to 85v and back as the ignitor is heating, however, I have replicated that behavior with 2 different ignitors and 2 different control boards, so I can only assume that is normal. Maybe I'll try 240v hookup and see if that changes anything.

-Ted

Sitkom · Nov 19, 2018

Switched it to 240V, no change. Ugh.

kadavis · Nov 20, 2018

Put your manometer on the manifold side of gas valve and then go through the ignition cycle. Check the reading with the heaters specification

Sitkom · Nov 21, 2018

Yeah, I've been playing around with pressures on the line supply side where the tap is. Ramped the LP supply side at the tank to 12.5" from 11" and did various ignition cycles with the regulator adjustment screw from nearly full out (closed) to full in (wide open). No change ignition-wise, though when all the way in, the pressure does drop to ~9", which makes sense as it's letting the gas pass unrestricted. When adjusted out, it drops maybe an inch to 10.5-11", which would reinforce that it is not passing a lot through the valve, so it would seem it's working. I have not checked the manifold side independently, just indirectly by watching the pressure when it opens on the line-side. I'll try that next.

Sitkom · Nov 22, 2018

Happy Thanksgiving everyone! So, all systems checked out. Power board, control board, wiring, ignitor, flame sensor, gas supply pressure, manifold pressure, gas orifices, fan. Still no ignition. Suspected that there was simply too much air flow to allow for ignition, so I opened the top, loosened the fan and shifted it a bit so that it drew some air from outside the combustion/heat exchanger area. Voila. Ignition. It is a design flaw in this version of the heater.

In the IDL2, unlike the current FD rev of the H-series heaters, there is no intake baffle plate to regulate airflow. In the IDL2 there is simply an open hole and there is no way to regulate the airflow through the ignition/combustion area.

So there are a few options to resolve this.

- introduce a gap between the fan shroud and the combustion chamber to bleed off some air flow through the combustion chamber. One method is to remove screws on one side of the fan housing, bend one of the mounting tabs down to act as a spacer and reattach the other screw, but leave a small gap.
- insert an FD-series baffle or a mesh screen between the fan and the combustion chamber to reduce the airflow
- add a potentiometer on the power lead to the fan to dial-down the fan speed

There are advantages/disadvantages to each. The tab-bending method is the easiest, but it is hard to control the amount of air diversion. The FD-baffle or mesh grill over the hole is a 'fixed' reduction in airflow, so if it doesn't change the airflow enough, you're stuck with one of the other methods. The potentiometer provides unlimited control of the fan speed, but may cause the control board to throw an error code or potentially damage the control board. All three methods reduce airflow through the combustion chamber, which will slightly reduce the BTU output of the heater. When you modify the airflow, be sure to adjust the manifold-side gas supply so you have a solid blue flame and not any yellow-flame (sooty flame) on the heat exchanger.

Ideally, what Hayward should have done is implement a variable speed fan and a perhaps an anemometer or mass airflow sensor. In addition, they could have programmed a reduced the fan speed at ignition and then ramp to full speed after the flame is sensed.

Anyway, for those of you with ignition issues and IF codes with IDL2 and older heaters when all the controls and gas supply checks out, it is likely an airflow issue. Adjust the fan before you throw parts at the heater. Hope this helps!