Fireplace has a mind of it's own!
I used to post regularly on this site about 8 years ago.... I'm a fridgie that should have retired by now. But here I am, still complaining about carrying too many tools at once onto a roof top, etc.
The question I'm posing, to me, seems to defy physics. As many of you will simply shake your head at your monitor as you sip on a Budweiser... I'm not far, shrugging my shoulders at my monitor also drinking my Budweiser.
I've repaired, installed, and trouble-shot many fireplaces, and ran into many anomolies. But this one seems to leave me short. I'll spell out the situation... and see what some of you cats think.
30,000 btu. Milivolt system. Originally had a gas valve (Nat Gas, @ 3.5" w.c.) No thermostat (jumpered out for the time being). NO fan assembly installed, although it's wired for that option. And as my own Mother spins in her grave over this.... NO Safeties factory installed, other than a pilot safety with a typical 'thermo-couple copper clad threaded termination to the body of the gas valve. No limit control or temp snap disc at all.
The fireplace runs well, when we jumpered it out for a call for heat. It ran for almost 20 minutes to the second. Then both the gas valve shut off, as well as the pilot. Rendering the fireplace dormant.
1. The fire place was new off of a show room floor. Until we hooked it up, it had never been fired.
2. Gas pressure (Natural Gas) was again measured at 3.6" w.c.
3. Fire place was vented (concentric venting) exactly to manufacturer's specs. No wind or poor inlet air conditions were or are part of this problem on how the chimney/inlets are positioned outside the building.
4. During the 'burning process', the gas flame is the typical indigo blue, with no harsh burning characteristics, with only the most minimal yellow tipping to the flame on both 'Hi' and 'Lo' settings.
5. The pilot flame is 'text book' perfect on the Power-pile. 715 mv open... 460 mv in operation.
6. 20 minutes, the flame and pilot are burning magnificently until then, a click happens and both shut off like a 'limit' might do. (Remember, it's just the Powerpile, gas valve. with the TH terminals jumpered.
7. Tried a second brand new Power-pile, same result.
8. Tried a second thermo-couple, same result.
9. Suspected defective valve with all other easier options addressed... and replace it with a Robertshaw Fire Place gas valve, equally rated, only this one did not have the thermo-couple terminations on it... thus we
even eliminated one more safety (for testing purposes).
10. HOWEVER, the new Robershaw valve... bought us 10 more minutes.... so now it runs for 30 minutes before it 'clicks' off.
11. Tried running the FP with the glass front off - same result after 30 minutes.
I've considered elements like thermal drafts that might pull the pilot flame away or partially off of the Power pile. NOPE.
I've considered a shortage of primary air, or a non-supportive secondary air. Flame is perfect until it shuts off. NOPE.
Heck, I even went out and picked up more Budweiser! Didn't seem to help.
Thanks guys 'n gals!
Never heard of "Josten" brand fireplaces and a quick Google failed to reveal them. Is that some local store you bought it from? Try to locate the rating plate with make and model.
Flame should not be indigo blue on a direct vent--should be blue bases with nice prominent yellow tips. I hear what you're saying about thinking the venting is perfect but what you're describing could be ghosting out or oxygen starvation. Try to watch the fire as its about to drop out. If it turns a transparent blue and the flames lift off the burner flying around inside like ghosts, then you have a venting problem. Sometimes its just a failure to remove all the insulation packing from the vent collar on the unit itself, sometimes a damages section and sometimes on long runs, it becomes too much as the pipe heats up and the thermosyphon effect fails. That's a high closed mv even though jumpered out. Try to get burning mv TH-Tp/TH. Feel the valve just before its due to drop out. Do you think the valve is getting hotter than 175F, which its rated for? Look at the pilot flame after burning for awhile. Does a previously stable flame begin to wobble and pull off the TC? Again, that's usually a venting issue. No mention of inlet gas pressure under full load with Fp and all other gas appliances firing.
If that doesn't work try Guinness.
Keep the fire inside the fireplace.
double post. Crazy system attacked me, I swear and no, I haven't had any Guinness.......................................... .................................................. ......................yet
Keep the fire inside the fireplace.
If(a very big if) the venting is in good working order and fireplace is designed correctly, it has to be valve or thermocouple(or thermocoupler if you are knocking 'em back) since you replaced them both. there is nothing wrong and you are drunk. On a serious note, at the 29th min check the milivolts at valve and see if the voltage is dropping off. Also that is a high milivolt reading for having it under load suggesting a bad connection.
I too was having issues ,does this have a ignition control ,I have a fireplace control made by sit ,the tech I was talking to states it has a timing mechanism (runs 6 hours ) .This is a built in safety so people dont run these 24 hours ,I s your unit locking out ,I also had to reseal my b vent pipe I was drawing exhaust into my intake and starving fire out, good luck