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Question

Good morning,

I have a Robertshaw millivolt gas valve part number 7000MVRLC in my fireplace. It has worked well until this year. When attempting to light the pilot, the pilot will not stay lit when the valve is released after 30-60 seconds. I replaced the thermocouple with new, same problem. Does the entire valve need to be replaced? If it can be cleaned or rebuilt, I am very comfortable permaing this task.

Thanks.

Rick Ruo
Nashua, NH

Submitted: 111 days and 19 hours ago.

Category: HVAC

Value: $15

Status: CLOSED

Posted by Rickheatdoc 111 days and 19 hours ago.

Answer

Hi Rick
Only the top 1/3 of the thermopile generator (similar to a thermocouple) should be in the pilot flame. If this is the case check the output of the thermopile. You should be getting a reading of 600 to 750 mv. If you are and the pilot won't stay lit when you release the pilot light button on the gas valve then you probably have a bad gas valve.
One other thing to be aware of, I have run into situations where the burner flame on gas fireplaces can impinge on the cold junction ( bottom 1/2) of the thermopile putting out the pilot. This doesn't sound like it directly relates to your problem but it is something you be aware of. So watch out for stray flames near the thermopile when you get this thing going again.

111 days and 19 hours ago.

Reply

Thank you.

The thermopile is adjusted so about 1/3 is in the flame. The manual mentions that the thermopile's output should be about 350 milli volts. It is, on both the old and the new thermopiles. Is there any maintenance that can be performed on the valve, short of full replacement? If full replacement is needed, can you recommend a vendor.

Thanks again.

Accepted Answer

You must have one of the lower output thermopiles. When gas valves fail the only recourse is to replace them. It is possible but unlikely that you will find a millivolt gas valve at one of the big box stores. A local plumbing supply house is your best bet. If that is not an option you can try these guys online.

http://americanhvacparts.com/index.htm

Accepts:
Expert:	Rickheatdoc
Pos. Feedback:	100.0 %
Answered:	8/3/2009

HVAC c&ontractor/tech

Over 40 years trouble shooting & installing heating equipment licensed oil & gas tech

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