How to Check Manifold and Inlet Pressure on a Gas Furnace - Tips on How to Maintenance a Gas Furnace

[@jasonbrand9812]

Thanks bro, just bought the same fieldpiece manometer

[@MegaLuisvelasco]

Excelent video and right to the point, thank you

[@sarahchanel7820]

Good work brother

[@HVACTechKnowledgy]

Thanks alot!

[@qzorn4440]

A most excellent video. Thanks.

[@HVACTechKnowledgy]

No prob! Thanks for watching

[@l.a.m7645]

What size brass barb fittings did you use?

[@roberts1159]

Do you always do a inlet and outlet pressure test during a maintenance or just if the flame pattern does not look right ? What if you don’t have a pressure regulator on the inlet side of the gas valve ? Thanks for sharing.

[@HVACTechKnowledgy]

No I don't always check gas pressures. I'll usually check if the flame sounds weak or aggressive or if my temp rise is off. Also you still want to check the inlet pressure whether there's are regulator or not.

[@Talentman18]

Should I get the wireless monometer? Or the SDMN6?

[@HVACTechKnowledgy]

Wireless all day for me! Although I'm beginning to see the benefits of not having to sync to Bluetooth every time I want to use an instrument

[@Talentman18]

@@HVACTechKnowledgy for aA/C season I will stick with the wireless. And for heating season I will stick with the instruments.

[@iReP809]

Where can I get a manifold just like that one ? The 3rd burner and the end of the manifold is letting out too much of a flame and it’s burning the inside of my furnace. Any suggestions !?

[@HVACTechKnowledgy]

Hey usually I'm all for DIY repairs its one of the reasons I started this channel but Honestly if you don't have the proper equipment to test a combustion Appliance IE combustion analyzer menometers temp probes Id probably just try to call out someone who does as you don't want to be doing experimental repairs on something that literally contains a active fire inside of your house.

[@amplifiedrecoil9639]

How do you change the pressure though if it wasn't reading perfect?

[@butlerstouchHVAC]

when do you usually check the gas pressure? what would make you use these tools to adjust the pressure

[@bernardocisneros4402]

You definitely want to check it when replacing the valve, and when having problems and you think it's related to gas pressure.

[@danielantoniodiaz3564]

If you have a high inlet gas pressure and the out is at the rated 3.5" w.c., can this cause incomplete combustion?

[@HVACTechKnowledgy]

If the inlet pressure is high enough to defeat the gas valve regulator and affect the manifold pressure then yes

[@threestans9096]

@@HVACTechKnowledgybut he says it is AT that… failed regulator, leaking more that can’t be measured?

[@mark.r8900]

Hi, I have a lennox mid efficiency single stage gas furnace. The manifold on rating plate is 3.5"wc. But I am only getting 1.7"wc. I adjusted to 3.5"wc according to the rating plate. But the furnace overheats and my temperature rise is out of specification. The furnace also intermittently short cycles. Can this be a bad gas valve? Thank you.

[@HVACTechKnowledgy]

What type of manometer are you using? If it's digital did you zero it out before checking? Did you check with another instrument? Also what caused you to check the gas pressure in the first place?

[@bernardocisneros4402]

No, it's NOT a bad gas valve. I think the last person to adjust it, addressed the sympton and not the cause. That valve should be set to 3.5 not 1.7 WC. You're underfiring at 1.7. The cause is going to be airflow, so you want to look in ducting for any obstructions and take out blower fan to clean it. When they get dirty, their airflow decreases exponentially. First clean the blower fan, and if that doesn't fix it, check all ductwork for obstructions. Especially the flue. If you already fixed it, please let us know what fixed it. I'm sure it will help someone in the future.

[@beefing313]

👍🏾👍🏾👍🏾

[@JULZ_RULZ]

My husband is an HVAC installer and he noticed in our brand new HEIL 4 ton a faint smell of gas near the manifold on shut down. It dissipates as soon as he opens the front panel. Majority of stuff I read say it's normal for a faint smell until gas completely dissipates but I thought I would ask anyway. Our last unit died after 22 yrs...it was a Carrier. Is this a new "green/high efficiency" issue?🫤 Thanks😊

[@BrianSpell-k6c]

Do you need to use a manometer?

[@cilopez155]

Yes

[@thomasbutler-k6c]

Why does this system have a preliminary external regulator? Thanks!

[@HVACTechKnowledgy]

Because the inlet gas pressure is too high of a pressure for the gas valve to meter properly so it needs to be stepped down around 7 to 10 in of water column before the gas valve steps it down to 3.5 in.

[@richbredsten349]

@@HVACTechKnowledgy is it 2 pounds of pressure on the inlet side of regulator?

[@bernardocisneros4402]

@@richbredsten349 I don't know what the pressure is before the stand-alone regulator but the pressure before the regulator in the valve is about 8 inches of Water Column which equals about one-third of a PSI

[@frankkoppen7281]

2 years ago , but is this lp -or- ng

[@HVACTechKnowledgy]

Natural Gas