odd fireplace pilot problem

how · 12-10-2011, 12:30 AM

One of my customers has intermitant gas shut downs on a direct vent Valor gas insert fireplace after it's been on for a while. He's replaced the thermocouple a few times and the pilot flame is strong. This unit is very simple with an igniter, thermocouple, gas valve and no limit controls. He's about to try a gas valve change (expensive) but when he asked me to look at it while I was servicing his furnace, I noticed the very blue main flames became softer and more more yellow the longer it burned. This direct vent system is one vent pipe within another but these both terminate at the same length at the immediate outside surface of the house. Any direct vent terminations I've seen have had staggered lengths or some other system for preventing the recirculating of combustion fumes, so I am wondering if it's the real pilot problem?
Anyone else seen recycled combustion fumes from a sketchy termination.

**beenthere** · 12-10-2011, 07:15 AM

Wind can cause it, if the thermocouple went out, and he didn't get the burner compartment sealed right.

That type of termination is common, and seldom gives any problem with the pilot.

yuri · 12-10-2011, 08:07 AM

all the direct vent fireplaces we have use a metal concentric termination kit which is usually square but I cannot find the exact pic. sounds like the draft is changing as it warms up and decreasing for some reason giving him yellow flames from less oxygen. probably needs a factory oem termination kit to prevent wind affecting the draft and flame. only a oem factory one is safe and UL approved etc.

how · 12-10-2011, 12:03 PM

The pilot apparently never goes out on its own. The burner compartment may not be sealed perfectly as one of the four holding screws (at the bottom) holding the glass in place is stripped. (I suspect it was a DIY project). No co leakage detected but it may be drawing in house air.
Yes that issue will need to be addressed!
It was the piping within the direct vent termination that caught my eye because every set up that I've seen has had one vent protrude beyond the other. The owners instalation instructions for that vent kit talks about cutting both vent pipes to fit but makes no mention of the length of either within the termination cap which is little more than a 6" debris guard. I was thinking of suggesting that he add a bit of an extention within the termination guard to the smaller inner vent pipe before trying a gas valve swap but I'm wondering if this is a bit of a red herring since the install instruction made no mention about it..

yuri · 12-10-2011, 12:45 PM

I would take red RTV silicone and seal the door 1st. Fireplaces are VERY finicky and if you mess with the term kit it will change the draft and you could get flames lifting off the burners etc.