Natural Gas Pressures - - - - - (Robershaw)

[BenTMann]

On a gas furnace, I hav more than 20 inch wc pressure of natural gas coming into the valve but it is OK because there is 3.5 going out.

This is new to me. Everything is new to me.

I learnt that for Nat gas it should be 5"wc in and 3.5"wc out.

And for LP it should be 15"wc in and 11"wc out.

So when I first took the incoming reading I thought I would have to put a regulator before the valve, but the system has been running like this for several year.

BTW, This call was for pilot not staying lit. Customer had changed the thermocoupler and still did not fix it. I clean the recepitil where the thermocoupler screw in the valve and made sure the sensor was in the flame and it worked.

This gas valve is a: Robertshaw-Grayson with the following number on the data plate.

7200ERCS-1
7C7-F8F-055 Max 1/2 psi
Nat - 3.5 LP - 11
24vac
6244913

The furnace is a Nordyne:
Model #: MGHA-070ABFC-05
Ser #: MGH9511-07309

I haven't done any reserch on this valve yet but I'm figuring that it will receive 1/2 psi pressure and take it down to the correct level of 3.5" wc.
[?]

It's a great life.

[16x80]

BenTMann

Like your posts so far! You have been helpful, Thank you!

As for 20 inches of WC coming in WOW I have never in my life seen that much pressure on a natural gas supply! The gas valve will only allow regardless of incoming 3.5" of WC out! Keep a new thermocouple close by for a easy fix when it does go out finally!

If it ain't broke don't fix it!

16x80

[BenTMann]

The problem is solved. Gas company's meter provided about a pount of pressure coming out and going to meter. The problem was there was no regulator between meter and house.

It had been like this for 6 years. This was one lucky lady. There was enough pressure there that could have blown out here gas valves. I put a regulator going into the house which brought the pressures before the gas valve down to 7"wc.

The luckiest thing is that I checked the pressures when I fixed the pilot light. This I normally do not do. I did this time to try out my new UEI EM150 digital manometer. Of course the presures on the outlet side of the furnance gas valve were ok at 3.5"wc. "Just for the heck of it", I wanted to see what my new toy would read on the incoming pressure. This was when it over read on my meter. I then used my old anolog meter and confirmed the proplem.

Leason learnt = it dosen't take that long to check pressures, do it on each new customer or whenever in doubt.

Ben

[Utilitygirl]

I JUST READ YOUR PROBLEM. DID YOU HAVE A RED INDEX(COMPENSATING) ON YOUR GAS METER? WHEN YOU CHEKED IT WITH YOUR DEVICE DID YOU HAVE IT SET ON H20 SETTING FOR INCHES OR LBS? 2 LB SYSTEMS FROM METER NEED AN INCHES REGULATOR TO BREAK IT DOWN FOR HOUSE LINE. JUST CURIOUS WHEN I READ 20 IN, ARE YOU SURE IT WAS NOT 2.O PSI. gLAD YOU GOT IT FIXED, HE WAS RIGHT YOU COULD HAVE HAD A BIG PROBLEM.

Utilitygirl