Empire RH 35 pilot keeps going out

[meaty]

Ok so I have an RH 35 in a rental unit

Recently it has been giving problems.

Background: The unit is on the 2nd floor and vents into the chimney flue. the building is circa 1900 and flue is not lined. In the basement there is a 30000 btu gas furnace that heats the first floor and 2 water heaters that all go into the chimney. I made sure everything is sealed tight with chimney cement. I put a match to the back to the space heater and the flame gets sucked into the chimney so I am getting good draft I believe. There was an older space heater in this unit with no spill switch before I replaced with this one in 2009. There are 2 carbon monoxide detectors in the room with this unit that have not registered any CO ever.

First I jumped the spill switch and the thing was running good. Then I hooked the switch back up and it would blow out. I think it was getting too hot (too much gas pressure) so I had a gas valve installed. Replaced the spill switch limit. Replaced the fan limit. It ran good for a few weeks, no complaints from tenant. And there was a huge difference in the heat that was coming from it due to the reduction in gas pressure.

Now it starts going out again. So I Replaced the thermo couple. Still blows out. It runs for a while then goes out. Its been windy could that do it?

Do you think I need to adjust the pilot flame since I reduced the gas pressure? It doesn't really go past the thermocouple like it should. If the pilot flame is too small would I be able to get it running like I can and then it blows out after a while? Or do you think I'm still having spill switch issues?

How do I adjust the pilot flame?

 

[DAKSY]

Can you post a pic of the front of the gas valve? It sounds like your pilot may be too low. Most gas valves have an adjustment screw to make sure the pilot is strong enough... As a rule of thumb, the pilot flame should engulf the top 3/8"of the thermocouple to ensure correct millivolt generation.

 

[xtrordinair]

what did you do to reduce the gas pressure?I hope you used a manometer to set the pressure to the right specs.NG set to about 3.5 inches and LP set to around 11.5 inches.

 

[ruserious2008]

I'm dealing with the same unit and same thing. Installed into an exterior chimney (Brick on outside wall- not thru interior of house) in 2008. I lived there at that time and we had problems with the pilot going out the first year, mostly on warmer nights (say 40F +) Thru observation I would see the pilot would just get
blown out when the main burner came on. Then the problem went away in 2009 and it has run fine until a few weeks ago. Had my regular service guy come by and he just looked at the flames, said it was good and that these units always do this and tried to sell me a new one.
So next day I watched it as I turned the thermostat up and down and within minutes I watched the pilot blow out (or maybe "go out" is more accurate and I should not be assuming its "blowing out"??) as the burner came on. I took the pilot unit out and it was all crapped up with white gunk in the orifice which I blew out with compressed air in a can and reinstalled it and it I spent two hours turning it off and on and slowly letting it heat up and turn off, then up the thermostat again over and over. It got good and hot and worked fine. Worked for about 10 hours and poof no pilot. Found on recommendation a furnace repair guy who on the phone obviously knew these units well, he came and looked at it, repositioned the thermocouple and could not find anything wrong and left and poof it blew out a few hours later. My poor tenants are justifiably frustrated and so am I. I can accept the "bad product" or bad draft and the spill switch is overheating theory IF someone could tell me why it worked good for 5 years until recently.
Also two gas water heaters in the basement that vent into this chimney also - this unit is also on a second floor.
Any ideas?

 

[ajaynejr]

I am suspecting although I have not proven that the carbon monoxide interlock under the control box where the tube for the thermocouple comes out could be defective.

I had one of these heaters (RH25 model) and found that if I jiggled the (black) cable going to the interlock, the heater and pilot shut off. I returned the heater for exchange.

Regarding blow out of the pilot, that could happen if the burner holes nearest the pilot are dirty and blocked. When the heater wants to turn on, the gas comes out of the other holes for a few seconds before gas drifts over to the pilot light and then it starts semi-explosively, probably blowing out the pilot in the process.

 

[EmpireTech]

Are we dealing with a Natural gas unit? If so check the manifold pressure through the valve, if this is high it can be the cause of blowing the pilot out when the unit comes on. I have found that making sure the gas pressure is correct 4" W.C. solves this problem. you can call tech service and speak to the tech guys they can offer advice.