Heat-N-Glo (SL32) gas with DSI Won't Lite

[rud]

I have a 20 yr. old, Heat-N-Glo SL32 direct vent. It has the Fenwal Direct Spark Ignition and it will not light.


In fact, it’s been this way for about 10 years and it’s time to fix it or replace it. I removed the logs and did a thorough cleaning including sanding the spark rod and ground on the igniter. I also cleaned ground wire & igniter wire contacts. I then checked continuity of the grounds and the spark igniter rod & wire. Everything is in order.

With the gas on, I flipped the rocker switch to ON and I hear a faint high-pitched whine (which I assume is the gas valve purging?) for about 4-5 sec. then it shuts off with no spark & no flame (lockout?). Repeated attempts fail also.

I do get a spark if I turn the rocker switch off after 1-2 seconds. So the module is capable of producing a spark.

I’ve also unhooked the spark igniter wire at the module then placed a grounded wire 3/16” from that connection and flipped the rocker switch on. Here again, I do get a spark when I switch off the rocker.

Questions: What is the normal spark pattern? Should the module/igniter be constantly sparking during the initial 4-5 secs. Or does it only spark once at the end of purge? Is this module dead or should I try some other test? Maybe it’s not getting gas and therefore shuts down because it does not sense a flame? I'm a novice with these systems.

 

[DAKSY]

Is that the EXACT Fenwal Module?
What is the model number? Can't read the number.

 

[rud]

The Heat-N-Glo part is 398-592 - Fenwal part number is 05-296423-750. I found some info about the 05-29 series - there is no prepurge - after power on the main valve opens and the is spark (unclear if it's single or continuous spark).

 

[DAKSY]

The Heat-N-Glo part is 398-592 - Fenwal part number is 05-296423-750. I found some info about the 05-29 series - there is no prepurge - after power on the main valve opens and the is spark (unclear if it's single or continuous spark).

This is what I found. Not sure if it's helpful.

http://www.parts4heating.com/Fenwal-05-296423-750-24-VAC-Direct-Spark-CSA-p/05-296423-750.htm

These units were in use before I got into the hearth business. Don't have a whole lot of service knowledge in this area. I seem to remember that most homeowners decided to have their units pulled out & replaced with newer standing pilot types after they were informed of the module replacement charges. Maybe heatsource or barmstrong2 will chime in...

 

[rud]

I seem to remember that most homeowners decided to have their units pulled out & replaced with newer standing pilot types after they were informed of the module replacement charges...

I guess it's no coincidence - that's what I was contemplating checking the replacement costs of over $400 for the module & valve. If I could get by for $200 - that would be nice.

I had already downloaded the rough-in framing schematic and it appears the current model SL550 would slip easily. I think they are around $1700.

I was also contemplating just replacing some of the guts like: module, valve, transformer and pilot assbly from the SL550. I could do that for about $250 and I would have an IPI spark ignition pilot assembly, which I assume would be the preferred setup.

 

[DAKSY]

Sorry about my last post, I didn't check to see if the link came thru...

So I added it...