please help

[ozon depletor]

hello everyone this is my first entry using this service. my question is in dealing with gas fireplaces. i have been in the hvac field 18 yers now but never serviced gas fireplaces. i am having a problem with a robertshaw/grayson gas valve model# 7000mvrlc serial#711-701-417. this is the second valve that i have installed along with a new thermopile. with both valves they worked for 24-48 hours then the main burner will not ignite. although i think i understand the sequence of operation can anyone explain it to me and give me some trouble shooting tips before the homeowner loses his patience. thanks in advance

[logdoc_rob]

I do not mean to come across harsh, but it may be best to refer this issue to a trained fireplace professional. There are several safety systems in place that can disable the fireplace for many reasons.

If you don't get it right, someone could get hurt.

[SeattlePioneer]

hello everyone this is my first entry using this service. my question is in dealing with gas fireplaces. i have been in the hvac field 18 yers now but never serviced gas fireplaces. i am having a problem with a robertshaw/grayson gas valve model# 7000mvrlc serial#711-701-417. this is the second valve that i have installed along with a new thermopile. with both valves they worked for 24-48 hours then the main burner will not ignite. although i think i understand the sequence of operation can anyone explain it to me and give me some trouble shooting tips before the homeowner loses his patience. thanks in advance

Ummm. It's pretty clear that guessing about what's causing the problem isn't a good troubleshooting method.

More than likely, you are losing millivolts somewhere along the main burner ignition circuit, resulting in a marginal ability to open the gas valve. I'd start by walking the circuit and seeing what the millivot read are at each part and connection.